FINAL DRAFT                               Chapter 6  IPCC WGII Sixth Assessment Report

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2                     Chapter 6: Cities, Settlements and Key Infrastructure

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4 Coordinating Lead Authors: David Dodman (Jamaica/United Kingdom); Bronwyn Hayward (New
5 Zealand); Mark Pelling (United Kingdom)

 6

 7 Lead Authors: Vanesa Castán Broto (United Kingdom/Spain); Winston Chow (Singapore); Eric Chu
 8 (USA/Hong Kong, Special Administrative Region, China); Richard Dawson (United Kingdom); Luna
 9 Khirfan (Canada); Timon McPhearson (USA); Anjal Prakash (India); Yan Zheng (China); Gina Ziervogel
10 (South Africa)

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12 Contributing Authors: Diane Archer (Australia/France), Chiara Bertolin (Italy), Shauna Brail (Canada),
13 Anton Cartwright (South Africa), Mikhail Chester (USA), Sarah Colenbrander (Australia/Switzerland),
14 Tapan Dhar (Bangladesh), Barbara Evans (United Kingdom), Sudharto P. Hadi (Indonesia), Wiwandari
15 Handayani (Indonesia), David Hondula (USA), Twan van Hooff (The Netherlands), Sirkku Juhola (Finland),
16 Christine Kirchhoff (USA), Sari Kovats (United Kingdom), Hayley Leck (South Africa/United Kingdom),
17 Pablo Méndez Lázaro (Puerto Rico), Tischa Muńoz-Erickson (USA), Vishal Narain (India), Marta Olazabal
18 (Spain), Luis Ortiz (Puerto Rico), Angelica Ospina (Colombia/Canada), Emmanuel Osuteye (Ghana), Chao
19 Ren (China), Rukuh Setiadi (Indonesia), Shalini Sharma (India), Wan-Yu Shih (Taiwan, Province of China),
20 Gilbert Siame (Zambia), Faith Taylor (United Kingdom), Jennifer Vanos (Canada), J. Jason West (USA),
21 Linda Westman (Sweden)

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23 Review Editors: Gian-Carlo Delgado-Ramos (Mexico); Patricia Romero-Lankao (USA/Mexico)

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25 Chapter Scientist: Linda Westman (Sweden)

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27 Date of Draft: 1 October 2021

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29 Notes: TSU Compiled Version

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32 Table of Contents

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34 Executive Summary..........................................................................................................................................3

35 6.1 Introduction and Points of Departure ....................................................................................................7

36  6.1.1 Background and Chapter Outline ...................................................................................................7

37  6.1.2 Points of Departure.........................................................................................................................8

38  6.1.3 Terminology and Definitions ..........................................................................................................9

39  6.1.4 Global Urban Trends ....................................................................................................................13

40 Box 6.1: Planetary Urbanisation and Climate Risk ....................................................................................14

41  6.1.5 Changes in the Global Enabling Environment .............................................................................16

42 6.2 Impacts and Risks...................................................................................................................................19

43  6.2.1 Risk Creation in cities, settlements, and infrastructure ................................................................20

44  6.2.2 Dynamic Interaction of Urban Systems with Climate...................................................................21

45  6.2.3 Differentiated Human Vulnerability .............................................................................................29

46  6.2.4 Risks to Key Infrastructures..........................................................................................................32

47 Box 6.2: Infrastructure Interdependencies ..................................................................................................34

48  6.2.5 Compound and Cascading Risks in Urban Areas.........................................................................39

49  6.2.6 Impacts and Risks of Urban Adaptation Actions ..........................................................................41

50 Box 6.3: Climate Change Adaptation for Cities in Fragile and Conflict Affected States........................41

51 6.3 Adaptation Pathways .............................................................................................................................47

52  6.3.1 Introduction...................................................................................................................................47

53  6.3.2 The Adaptation Gap in Cities and Settlements .............................................................................47

54  6.3.3 Adaptation Through Social Infrastructure....................................................................................49

55  6.3.4 Adaptation Through Nature-Based Solutions ...............................................................................57

56  6.3.5 Adaptation Through Grey/Physical Infrastructure.......................................................................63

57  6.3.6 Cross-Cutting Themes...................................................................................................................72

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1 Box 6.4: Adapting to Concurrent Risk: COVID-19 and Urban Climate Change ....................................72

2   6.3.7 Climate Resilient Development Pathways ....................................................................................76

3 6.4 Enabling Conditions for Adaptation Action in Urban Areas, Settlements, and Infrastructure.....78

4   6.4.1 Adaptation Experiences in Cities, Settlements and Infrastructures..............................................78

5 Box 6.5: Building Water Resilience in Urban Areas through Community Action and Activism ...........82

6   6.4.2 Institutional change to Deliver Adaptation in Cities, Settlements, and Infrastructure.................83

7   6.4.3 Solution spaces to address the `policy action gap'.......................................................................88

8 Box 6.6: Invisible Women: Lack of Women's Participation in Urban Authorities .................................92

9 Box 6.7: The Role of Urban Design in Local Adaptation............................................................................93

10  6.4.4 Limits of Adaptation Capacity at the Institutional Level ..............................................................94

11  6.4.5 Financing Adaptation in Cities, Settlements and Infrastructures.................................................96

12 Box 6.8: Challenges to Investment in Adaptation in African Cities ........................................................100

13  6.4.6 Monitoring and Evaluation Frameworks for Adaptation used in Cities, Settlements and

14  Infrastructures ............................................................................................................................. 101

15  6.4.7 Enabling Transformations ..........................................................................................................103

16 Case Studies...................................................................................................................................................105

17  Case Study 6.1: Urbanization and Climate Change in the Himalayas ­ Increased Water Insecurity for

18  the Poor.......................................................................................................................................105

19  Case Study 6.2: Semarang, Indonesia....................................................................................................106

20  Case study 6.3: Institutional Innovation to Improve Urban Resilience: Xi'xian New Area in China ...108

21  Case Study 6.4: San Juan: Multi-Hazard Risk and Resilience in Puerto Rico and its Urban Areas.....109

22  Case Study 6.5: Climate-resilient Pathways in Informal Settlements in Cities in Sub-Saharan Africa.110

23 Cross-Working-Group Box URBAN: Cities and Climate Change ..........................................................112

24 FAQ6.1: Why and how are cities, settlements, and different types of infrastructure especially

25  vulnerable to the impacts of climate change? ....................................................................................116

26 FAQ6.2: What are the key climate risks faced by cities, settlements, and vulnerable populations today,

27  and how will these risks change in a mid-century (2050) 2°C warmer world? ..............................117

28 FAQ6.3: What adaptation actions in human settlements can contribute to reducing climate risks and

29  building resilience across building, neighbourhood, city, and global scales? .................................118

30 FAQ6.4: How can actions that reduce climate risks in cities and settlements also help to reduce urban

31  poverty, enhance economic performance, and contribute to climate mitigation?..........................119

32 FAQ6.5: What policy tools, governance strategies, and financing arrangements can enable more

33  inclusive and effective climate adaptation in cities and settlements? ..............................................120

34 References......................................................................................................................................................122

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FINAL DRAFT                       Chapter 6  IPCC WGII Sixth Assessment Report

 1 Executive Summary

 2

 3 In all cities and urban areas, the risk faced by people and assets from hazards associated with climate
 4 change has increased (high confidence1). Urban areas are now home to 4.2 billion people, the majority of
 5 the world's population. Urbanization processes generate vulnerability and exposure which combine with
 6 climate change hazards to drive urban risk and impacts (high confidence). Globally, the most rapid growth in
 7 urban vulnerability and exposure has been in cities and settlements where adaptive capacity is limited ­
 8 especially in unplanned and informal settlements in low- and middle-income nations and in smaller and
 9 medium-sized urban centres (high confidence). Between 2015 and 2020, urban populations globally grew by
10 more than 397 million people, with more than 90 percent of this growth taking place in Less Developed
11 Regions. {Box 6.1; 6.1.4; 6.2.1; 6.3.2; 6.3.3.4; 6.2.2.2; 6.4.4}

12

13 The documentation of climate related events and observed human and economic losses have increased
14 since AR5 for urban areas and human settlements. Observed losses arise from single, compound,
15 cascading and systemic events (medium evidence, high agreement). Losses from single events include the
16 direct impact of heat stress on human health. Compound event losses arise from the interaction of single
17 climate hazards with at least one other hazard driver such as heat with poor air quality (e.g. from traffic
18 fumes or wildfire), flooding with poor water quality (e.g. from contaminated run-off and flood water), or
19 land subsidence. Cascading impacts are observed when damages in one place or system reduce resilience and
20 generate impacts elsewhere (e.g. when flood waters damage energy infrastructure causing blackouts and
21 knock on financial and human impacts). Losses become systemic when affecting entire systems and can even
22 jump from one system to another (e.g. drought impacting on rural food production contributing to urban food
23 insecurity) (medium confidence). In some cases, maladaptive responses to hazards have exacerbated
24 inequality in the distribution of impacts, for example shifting risk from one community to another. {Figure
25 6.2; 6.2.6; 6.3.4.1; 6.4.5; Cross-Chapter Paper 2; Cross-Working Group Box URBAN in Chapter 6}

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27 Evidence from urban and rural settlements is unequivocal; climate impacts are felt disproportionately
28 in urban communities with the most economically and socially marginalized, most affected (high
29 confidence). Vulnerabilities are shaped by drivers of inequality - including gender, class, race, ethnic origin,
30 age, level of ability, sexuality and nonconforming gender orientation - framed by cultural norms, diverse
31 values, and practices (high confidence). Intersections between these drivers shape unique experiences of
32 vulnerability and risk and the adaptive capacities of groups and individuals. Robust adaptation plans are
33 those developed in inclusive ways. However, few adaptation plans for urban areas and infrastructure are
34 being developed through consultation and coproduction with diverse and marginalized urban communities.
35 The concerns and capacities of marginalised communities are rarely considered in planning (medium
36 confidence). {Box 6.3, Box 6.4; 6.4.3.1; 6.4.5.2, Case study 6.7; Cross-Working Group Box URBAN in
37 Chapter 6}.

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39 The COVID-19 pandemic has had a substantial impact on urban communities and climate adaptation
40 (medium evidence, high agreement). The pandemic has revealed both systemic underinvestment resulting in
41 multiple, persistent health related vulnerabilities (many of which also exacerbate climate change risk) and
42 co-benefits for urban interventions to reduce future pandemic and climate change risk. The COVID-19
43 pandemic is estimated to have pushed an additional 119 to 124 million people into poverty in 2020, with
44 South Asia and Sub-Saharan Africa each contributing roughly two-fifths of this total (medium confidence).
45 At city level, community groups, NGOs and local governments face challenges to bring agencies already
46 working on social and economic development into coordinated action to reduce urban vulnerabilities and
47 manage risks. COVID-19 and climate change impacts are exacerbated by widening social inequality.
48 Addressing the causes of social vulnerability creates opportunity for transformative adaptation. {Box 6.4;
49 6.1.4; 6.2.2.4; 6.2.5; 6.4.1.3; case study 6.4; Cross-Chapter Box COVID in Chapter 7}

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51 The number of people expected to live in urban areas highly exposed to climate change impacts has
52 increased substantially (high confidence). An additional 2.5 billion people are projected to be living in

1 In this Report, the following summary terms are used to describe the available evidence: limited, medium, or robust;
and for the degree of agreement: low, medium, or high. A level of confidence is expressed using five qualifiers: very
low, low, medium, high, and very high, and typeset in italics, e.g., medium confidence. For a given evidence and
agreement statement, different confidence levels can be assigned, but increasing levels of evidence and degrees of
agreement are correlated with increasing confidence.

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 1 urban areas by 2050, with up to 90 percent of this increase concentrated in the regions of Asia and Africa.
 2 Projections of the number of people expected to live in urban areas highly exposed to climate change
 3 impacts have increased. Sea level increase and increases in tropical cyclone storm surge and rainfall intensity
 4 will increase the probability of coastal city flooding, with more than a billion people located in low-lying
 5 cities and settlements expected to be at risk from coastal-specific climate hazards by 2050 (high
 6 confidence). Sea level rise, increases in tropical cyclone storm surge, and more frequent and intense extreme
 7 precipitation will increase the number of people, area of urban land, and damages from flood hazard (high
 8 confidence). The main driver for increased heat exposure is the combination of global warming and
 9 population growth in already-warm centres, and the majority of the population exposed to heatwaves will
10 live in urban centres. An additional 350 million people living in urban areas are estimated be exposed to
11 water scarcity from severe droughts at 1.5°C warming, and 410.7 million at 2°C warming. {6.1;
12 6.2.2; CCP2}

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14 Many more cities have developed adaptation plans since AR5, but only a limited number of these have
15 been implemented (medium confidence). Many of these plans focus narrowly on climate risk reduction,
16 missing opportunities to advance co-benefits of climate mitigation and sustainable development,
17 compounding inequality and reducing wellbeing (medium confidence). However, an increasing array of
18 adaptation options are available. Nature-based solutions are now mainstream urban adaptation options and
19 there remains considerable scope for their wider application. Social policy based adaptation, including
20 education and the adaptation of health systems offers considerable future scope. Options of adapting physical
21 infrastructure are similarly advancing though at times constrained by existing infrastructure design and
22 location. The greatest gaps between policy and action are in failures to manage adaptation of social
23 infrastructure (community facilities, services and networks) and failure to address complex interconnected
24 risks for example in the food-energy-water-health nexus or the inter-relationships of air quality and climate
25 risk (medium confidence). Barriers to implementing plans include lack of political will and management
26 capacity, limited financial means and mechanisms (especially for smaller urban settlements) and competing
27 priorities (limited evidence, high agreement). {6.3.1, 6.4.3; 6.4.5; 6.4.5.1; 6.4.5.2; Figure 6.5}

28

29 The shift from urban planning to action in ways that identify and advance synergies and co-benefits of
30 mitigation, adaptation and Sustainable Development Goals (SDGs) has occurred slowly and unevenly
31 (high confidence). While there is ambition for joined up policy, action and research, this is still the exception.
32 One area of sustained effort is community-based adaptation planning and resilience actions which have
33 potential to be better integrated to enhance wellbeing and create synergies with the Sustainable Development
34 Goal ambitions of leaving no-one behind. Complex trade-offs and gaps in alignment between mitigation and
35 adaptation over scale and across policy areas where sustainable development is hindered or reversed also
36 remain. {6.1.1, Table 6.2; 6.1.5; 6.4.1.4; 6.4.3; 6.4.4}

37

38 Urban adaptation gaps exist in all world regions and for all hazard types, although exposure to the
39 limits to adaptation are unevenly distributed. Governance capacity, financial support and the legacy of
40 past urban infrastructure investment constrain how all cities and settlements are able to adapt (high
41 confidence). Critical capacity gaps exist at city and community levels that hinder adaptation. These include
42 the limited ability to identify social vulnerability and community strengths; the absence of integrated
43 planning to protect communities; and the lack of access to innovative funding arrangements and limited
44 capability to manage finance and commercial insurance (medium confidence). These can be addressed
45 through enhanced locally accountable decision-making with sufficient access to science, technology and
46 local knowledge to support widespread application of adaptation solutions. {6.3.1, 6.4.3; 6.4.5; 6.4.5.1;
47 6.4.5.2; Figure 6.4; Figure 6.5}

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49 Slow uptake of monitoring and evaluation frameworks constrains potential for developing climate
50 resilient urban development pathways (medium confidence). A lack of agreement on metrics and indices
51 to measure urban adaptation investment, impacts and outcomes, reduces the scope for sharing lessons and
52 joined-up action across interconnected sectors and places in the face of compound and systemic risks. These
53 constraints affect the potential for climate resilient development pathways. Limits to adaptation are often
54 most pronounced in rapidly growing towns and cities and smaller settlements including those without
55 dedicated local government. At the same time, legacy infrastructure in large and mega-cities, designed
56 without taking climate change risk into account, constrains innovation leading to stranded assets and with

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 1 increasing numbers of people unable to avoid harm, including heat stress and flooding, without
 2 transformative adaptation. {6.2.5; 6.3.3.3; 6.3.7; Figure 6.4; 6.4.4; 6.4.6 FAQ6.5}

 3

 4 City and local governments are key amongst multiple actors facilitating climate change adaptation in
 5 cities and settlements (medium confidence). City and local governments can invest directly and work in
 6 partnership with community, private sector and national agencies to address climate risk. Private and
 7 business investment in key infrastructure, housing construction and through insurance requirements can also
 8 drive widespread adaptive action, though at times excluding the priorities of the poor (medium confidence).
 9 Networked community actions can also go beyond neighbourhood-scale improvements to address
10 widespread vulnerability. Such actions include fostering roles of intermediaries and multiple spaces for
11 networked governance across scales of decision making, improving development processes through an
12 understanding of social and economic systems, foresight, experimentation and embedded solutions, and
13 social learning. Transnational networks of local government can also enhance city level capacity, share
14 lessons and advocacy (medium confidence). {Table 6.2, 6.3.3.4; 6.3.3.5; 6.4.1; 6.4.1.1; case study 6.2;
15 FAQ6.5}

16

17 Globally, decisions about key infrastructure systems and urban expansion drive risk creation and
18 potential action on climate change (high confidence). Urban infrastructure concentrates and connects
19 populations, physical assets and energy use. Urban expansion and the compromising of green infrastructure
20 and ecosystem services reduces adaptive capacity and can increase risk: the urban heat island ­ a product of
21 expansion ­ can add 2°C to local warming. How settlements and key infrastructure are planned, designed
22 and maintained determines patterns of exposure, social and physical vulnerability and capacity for resilience.
23 Unplanned rapid urbanization including peri-urban development is a major driver of risk, particularly where
24 cities and settlements are expanding into land that is prone to coastal flooding or landslides, or where there is
25 inadequate water to meet the needs of growing populations. Urban decision-making processes equally shape
26 how far low- and zero-carbon development can meet social needs ­ enhancing wellbeing while enabling
27 climate change mitigation and advancing the Sustainable Development Goals. {6.1.3; 6.2.3; 6.2.4; 6.3.3;
28 6.3.4; 6.3.5; 6.4.6; Cross-Working Group Box URBAN in Chapter 6}

29

30 Investment in urban adaptation has not kept pace with innovations in policy and practice (medium
31 confidence). Knowledge transfer and innovation in adaptation has broadened advances in social and
32 ecological infrastructures including disaster risk management, social policy and green/blue infrastructure,
33 especially where these are integrated with grey/physical infrastructure (medium evidence, high agreement).
34 Innovation has also taken pace at the interface of difference systems, for example ICT and water or energy
35 although financial investment has been slow to recognize and support these activities. Adaption finance
36 continues to be directed at large-scale grey/physical engineering projects, neglecting maintenance and
37 reproducing risk of stranded assets if climate change risk accelerates beyond planned-for levels. Finance
38 deployed at the interface of multiple, integrated adaptation measures can support climate resilient
39 development (high confidence). Access to finance is most difficult for city, local and non-state actors and in
40 conditions where governance is fragile. {6.3.3; 6.3.4; 6.3.6; 6.4.5; 6.4.5.2; Table 6.10; Table 6.11; Box 6.8;
41 case study 6.2; case study 6.3; case study 6.5}

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43 Global urbanization offers a time-limited opportunity to work towards widespread and
44 transformational adaptation and Climate Resilient Development (high confidence). Current dominant
45 models of energy intensive and market-led urbanization build high carbon dependency and high vulnerability
46 into cities, but this need not be the case. Integrated development planning that connects innovation and
47 investment in social, ecological and grey/physical infrastructures can significantly increase the adaptive
48 capacity of urban settlements and cities. Transitioning cities to low carbon development and equitable
49 resilience may lead to trade-offs with dominant models of economic growth based on housing and
50 infrastructure investment. Integrated planning approaches are important for Climate Resilient Development
51 to enable planning and monitoring of interactions between development, mitigation and adaptation. Urban
52 adaptation measures can offer a considerable contribution to Climate Resilient Development. This potential
53 is realised by adaptations that extend predominant physical infrastructure approaches to also deploy nature
54 based solutions and social interventions. The most consistent limit for all infrastructure types is in risk
55 transfer. Current adaptation approaches in cities, settlements and key infrastructure have a tendency to move
56 risk form one sector or place to others. Multi-level leadership, institutional capacity together with financial
57 resources (including climate finance) to support inclusive and sustainable adaptation in the context of

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 1 multiple pressures and interconnected risks, can help to ensure that global urbanization of an additional 2.5
 2 billion people by 2050; reduces rather than generates climate risk (medium confidence). {Table 6.7; Table
 3 6.5; 6.1.3; 6.3.6; 6.3.5.2; 6.4.7; Box 6.5; Cross-Working Group Box URBAN in Chapter 6; CCP2}

 4

 5 Intersectional, gender-responsive and inclusive action can accelerate transformative climate change
 6 adaptation. The greatest gains in wellbeing in urban areas can be achieved by prioritising investment
 7 to reduce climate risk for low-income and marginalised residents and targeting informal settlements
 8 (high confidence). These approaches can advance equity and environmental justice over the long term in
 9 ways more likely to lead to outcomes that reduce vulnerability for all urban residents. Participatory planning
10 for infrastructure provision and risk management to address climate change and underlying drivers of risk in
11 informal and underserviced neighbourhoods, the inclusion of Indigenous Knowledge and Local Knowledge,
12 communication and efforts to build local leadership especially amongst women and youth are examples of
13 inclusive approaches with co-benefits for equity. Providing opportunities for marginalised people, including
14 women, to take on leadership and participation in local projects can enhance climate governance and its
15 outcomes (high confidence). Since AR5, social movements in many cities, including movements led by
16 youth, Indigenous and ethnic communities have also heightened public awareness about the need for urgent,
17 inclusive action to achieve adaptation that can also enhance wellbeing. {6.1.5; 6.3.5; 6.4.1.2; 6.4.7; Box 6.6,
18 case studies 6.2; 6.4 FAQ6.3}

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20 City and infrastructure planning approaches that integrate adaptation into everyday decision-making
21 are supported by the 2030 Agenda (the Paris Agreement, the Sustainable Development Goals, the New
22 Urban Agenda and the Sendai Framework for Disaster Risk Reduction) (high confidence). The 2030
23 Agenda provides a global framework for city and community level action to be points of alignment between
24 Nationally Determined Contributions, National Adaptation Plans of Action, and the Sustainable
25 Development Goals. City and local action can complement ­ and at times go further than national and
26 international interventions. Similarly, the Convention on Biological Diversity offers a global agreement
27 through which nature-based solutions can be viewed as benefits for biodiversity, social justice and climate
28 resilience. However, there is no specific global agreement that addresses informality and city level climate
29 adaptation. More comprehensive and clearly articulated global ambitions for city and community adaptation
30 will contribute to inclusive urbanization, by addressing the root causes of social and economic inequalities
31 that drive social exclusion and marginalization, so that adaptation can directly support the 2030 Sustainable
32 Development Agenda (high confidence). {6.1.1; Table 6.2; 6.2.3.2; 6.4.1.4; case study 6.4}

33

34

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 1 6.1 Introduction and Points of Departure

 2

 3 6.1.1 Background and Chapter Outline

 4

 5 Cities and urbanising areas are currently home to over half the world's population. What happens in cities is
 6 crucial to successful adaptation (Grafakos et al., 2019). By 2050 over two thirds of the world's population is
 7 expected to be urban, many living in unplanned and informal settlements and in smaller urban centres in
 8 Africa and Asia (high confidence) (UNDESA, 2018). Between 2015 and 2020, urban populations globally
 9 have grown by about 397 million people, with more than 90 percent of this growth taking place in Less
10 Developed Countries (UNDESA, 2018). Projections of the number of people expected to live in urban areas
11 highly exposed to climate change impacts have also increased, exacerbating future risks under a range of
12 climate scenarios. Rates of population growth are most pronounced in smaller and medium sized settlements
13 of up to 1 million people (UNDESA, 2018).

14

15 Since AR5 there has been increasing understanding of the interdependence of meta-regions, large, small and
16 rural settlements which may be connected through key infrastructure (Lichter and Ziliak, 2017) including
17 national and trans-national infrastructure investments (Hanakata and Gasco, 2018). Almost all the world's
18 non-urban population and its provisioning ecosystems are impacted by urban systems through connecting
19 infrastructure and family and kinship ties, remittances and trade arrangements that influence flows of water,
20 food, fibre, energy, waste and people (Trundle, 2020; McIntyre-Mills and Wirawan, 2018; Zhang et al.,
21 2019; Nerini et al., 2019; Friend and Thinphanga, 2018). Many rural places are so deeply connected to urban
22 systems that risks are observed to cascade from one to the other ­ for example when drought in arable zones
23 leads to food insecurity in cities, or where flood damage to urban transport infrastructure leads to prolonged
24 isolation of small towns and rural settlements (Friend and Thinphanga, 2018; McIntyre-Mills and Wirawan,
25 2018). A focus of this chapter is the experience of a range of urban settlements, from small to large, and the
26 connecting infrastructure and formal and informal networks and systems that join them to each other. There
27 are close synergies with chapters 7 (Health, wellbeing and the changing structure of communities) and 8
28 (Poverty, livelihoods and sustainable development). There are further important synergies with Working
29 Group III Chapter 8 (Urban systems and other settlements) and the Cross-Chapter Paper 2: Cities and
30 Settlements by the Sea.

31

32 Well planned climate adaptation can have far reaching co-benefits for sustainable development, and
33 community wellbeing (Nerini et al., 2019; Tonmoy et al., 2020). However the varied success of cities'
34 responses to the global COVID-19 pandemic underscores how social and economic conditions, built
35 environments and local planning can exacerbate or reduce vulnerability and long term sustainable,
36 community wellbeing (Megahed and Ghoneim, 2020; Plastrik et al., 2020; Hepburn et al., 2020; Sarkis et al.,
37 2020).

38

39 Many of the significant sustainable development initiatives that have been proposed and implemented in the
40 last five years recognise the critical importance of cities, settlements and key infrastructure in responding to
41 the crisis of climate change (Zhang et al., 2019; Nerini et al., 2019). There is widespread acceptance of the
42 need for far-reaching responses by actors from the local to the global scales to make human settlements and
43 infrastructure more resilient (UNDP, 2021). There is recognition also of the considerable capacity in
44 settlements to meet climate change challenges, if the governance, financial and social conditions are in place
45 (Carter et al., 2015; MINURVI, 2016). And yet the implementation of climate adaptation planning lags
46 behind climate mitigation efforts in urban communities (Sharifi, 2020; Grafakos et al., 2019; Nagendra et al.,
47 2018).

48

49 Since the publication of AR5, there has been rapid expansion in policy, practice and research related to
50 climate change and human settlements. The 2030 Agenda for Sustainable Development (the Sustainable
51 Development Goals) agreed in September 2015, was preceded by the Sendai Framework for Disaster Risk
52 Reduction 2015-30 and followed shortly afterwards by the Paris Agreement (December 2015) (United
53 Nations, 2015b). These make explicit mention of "mainstreaming of disaster risk assessments into land-use
54 policy development and implementation, including urban planning" (Sendai Framework) (UNISDR, 2015).
55 The agreements identify "sustainable cities and communities" (SDG11) and "cities and subnational
56 authorities" (Paris Agreement) as important actors in integrating climate and development goals (Sanchez
57 Rodriguez, Ürge-Vorsatz and Barau, 2018). However not all urban SDGs have measurable targets yet, or

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 1 data particularly in regard to children and youth, the elderly and disabled (Klopp and Petretta, 2017; Reckien
 2 et al., 2017; Nissen et al., 2020). Clear procedures for linking climate adaptation in communities at all scales
 3 to the SDGs is lacking (Major, Lehmann and Fitton, 2018; Sanchez Rodriguez, Ürge-Vorsatz and Barau,
 4 2018).

 5

 6 The New Urban Agenda (NUA) (October 2016), with its focus on housing and sustainable urban
 7 development, commits its signatories to building resilient and responsive cities that foster climate change
 8 mitigation and adaptation (United Nations, 2016b). This agreement followed the Geneva UN Charter on
 9 Sustainable Housing, endorsed by 56 member states of the United Nations Economic Commission for
10 Europe (United Nations, 2015d). The NUA aims to ensure access to decent, adequate, affordable and healthy
11 housing for all while reducing the impact of the housing sector on the environment and increasing resilience
12 to extreme weather events (United Nations, 2016b). Voluntary, networked action led by cities was also
13 illustrated by a November 2019 call to Mayors and youth climate activists to sign a voluntary pledge in a
14 "Race to Zero" ahead of the Conference of the Parties 26, which included endorsing principles of a New
15 Green Deal (C40, 2019). Other voluntary, global, urban efforts have been led by the scientific community
16 including the Research and Action Agenda on Cities and Climate Change Science which aims to promote
17 research and reports (Prieur-Richard, Walsh and Craig, 2019).

18

19 These collaborative global changes are reflected in the bodies of literature assessed for this report. In AR5,
20 the section on `human settlements, industry, and infrastructure' contained three chapters: urban areas; rural
21 areas; and key economic sectors and services. This chapter covers the full range of human settlements: from
22 small settlements in predominantly rural areas, to large metropolises in both high-income and low-income
23 countries. It also assesses evidence of climate change impacts, vulnerability and adaptation on a range of
24 urban infrastructures including infrastructure that incorporates socio-economic, and ecosystem dimensions
25 (see 6.1.3).

26

27 This assessment also considers new literature about how enabling environments can support adaptation in
28 ways that are also sensitive to Indigenous knowledge and local knowledge (see below 6.1), social justice
29 (6.4.3.d) and climate mitigation (6.3.5.2). It builds on the findings of AR5 which highlighted the
30 concentration of global climate risks in urban areas, the complex causal chains that mediate climate impacts
31 for smaller settlements and rural areas, and the multiple issues shaping and influencing economic sectors and
32 infrastructure. This integrated chapter enables a more detailed analysis of the inter-connected drivers of risk
33 that affect urban people and settlements of different sizes. This discussion also highlights the inter-
34 connections within and between urban areas, and between different types of infrastructure and how these
35 complex relationships accentuate or limit the effects of climate change and the institutional structures that
36 play a critical role in mediating and govern these relationships.

37

38 This chapter has five main sections. The first elaborates on changes in the international policy context since
39 2014, highlighting the implications that this has for responses to climate change in cities, settlements and key
40 infrastructure. Section 6.2 is focused on observed and projected climate risks, paying particular attention to
41 the ways in which these are created through processes of urbanization and infrastructural investment. Section
42 6.3 takes an integrated and holistic approach to an assessment of adaptive actions relevant to key
43 infrastructures (those that form the material basis for resilience in cities and settlements, drive economies,
44 and are essential for human wellbeing). Section 6.4 assesses the enabling conditions and leadership qualities
45 associated with adaptation processes that can also meet the equity agenda of the Sustainable Development
46 Goals ­ to leave no-one behind including the role of governance, finance, institutions and emerging literature
47 around the limits of urban adaptation.

48

49 Case studies highlight how climate and other issues interrelate to create (or reduce) urban risk within and
50 between scales of decision-making. They illustrate how multiple levels of governance and formal and
51 informal decision-making sectors influence how risk production/reduction plays out across a range of urban
52 contexts and networks.

53

54 6.1.2 Points of Departure

55

56 The AR5 conceptualised cities and settlements as complex interdependent systems that could be engaged in
57 supporting climate change adaptation (Revi et al., 2014 8.8.2). Effective municipal governance systems and

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 1 cooperative multilevel governance supported adaptation action. The AR5 report expressed medium
 2 confidence that governance interventions can help develop synergies across geographical and institutional
 3 scales. Urban areas face challenges of infrastructure investment and maintenance, land use management,
 4 livelihood creation, and ecosystem services protection. AR5 also considered how urban localities can
 5 encourage incremental and transformative adaptation, build resilience and support sustainable development.
 6 The assessment identified the need for multi-level and multi-partner action in rapidly growing cities where
 7 institutions and infrastructure are still not established to meet the growing demands of the cities. However,
 8 there was only medium confidence that adaptation action was happening in the AR5 review period.

 9

10 The framing of `key economic sectors and services' in AR5 focused primarily on three infrastructural areas
11 (energy, water services, transport) and on primary and secondary economic activities (including recreation
12 and tourism, insurance and financial services). Cities, settlements and key infrastructure are also referred to
13 in the IPCC special reports released since AR5. The Special Report on Global Warming of 1.5°C examines
14 impacts of global warming on urban systems and infrastructure in the context of advancing sustainable
15 development and eradicating poverty. It highlights the risks facing residents of unplanned and informal
16 urban settlements, many of which are exposed to a range of climate-related hazards (Sections 3.4.8 and
17 4.4.1.3). The Special Report on Global Warming of 1.5°C also identifies green infrastructure, sustainable
18 land use and planning, and sustainable water management as key adaptation options that can reduce risks in
19 urban areas (SPM C2.4; C. 2.5), and highlights "urban and infrastructure" as one of four system transitions
20 required to limit warming to 1.5°C to create an enabling environment for adaptation (Section 4.3.3).
21 Innovative governance arrangements that go beyond formal `government' and political arrangements and
22 that include non-state actors, networks and informal institutions were identified as important in addressing
23 climate change and implementing responses to 1.5°C-consistent pathways (Special Report on Global
24 Warming of 1.5°C (Section 4.4.1 and 5.6.2). In addition, the Special Report on Global Warming of 1.5°C
25 mentions, with high confidence, the climate related health effects of urban heat islands, urban heatwaves and
26 increasing risks from some vector-borne diseases (illnesses caused by pathogens and parasites in human
27 populations) (SPM B 5.2). The report also notes both trade-offs and important co-benefits of sustainable
28 development in pursuit of climate-resilient development pathways that achieve ambitious mitigation and
29 adaptation in conjunction with poverty eradication and efforts to reduce inequalities (SPM D6).

30

31 The Special Report on Oceans and Cryosphere (SROCC) similarly emphasises the role governance plays in
32 reducing disaster risk, through planning, and zoning. It identifies vulnerability factors such as poverty, which
33 can undermine resilience and sustainable development in urban communities (SPM C31, Section 2.3.2.3; pp.
34 135; 164). The SROCC report shows that the emerging climate related challenges are impacting the
35 accessibility and availability of vital resources and blurring the public and private boundaries of risk and
36 responsibility (Cross-Chapter Box 3 p 99). According to the SROCC report, new governance arrangements
37 are emerging to address these challenges, including participatory and networked structures, and institutions
38 linking formal and informal networks involving state, private sector, Indigenous and civil society actors
39 (Cross-Chapter Box 3 p 99). The SROCC report calls for place-specific action because there is no single
40 climate governance panacea for the ocean, coasts, and cryosphere Cross Chapter box 3 p 99). The SROCC
41 report highlights evidence of the importance of inclusivity, fairness, deliberation, reflexivity, responsiveness,
42 social learning, the co-production of knowledge, and respect for ethical and cultural diversity in climate
43 related urban decision-making (Cross-Chapter Box 3). In addition, the Special Report on Climate Change
44 and Land notes that urbanisation can intensify extreme rainfall events over the city or downwind of urban
45 areas and have can significant consequences for heat island effects loss of food production posing additional
46 risks to the food system (SPM A5.3 and Cross-Chapter Box 4 in Chapter 2).

47

48 An additional research bridge between AR5 and AR6 was the IPCC Cities and Climate Change Science
49 conference in Edmonton, Canada March 2018. This generated a `Global Research and Action Agenda on
50 Cities and Climate Change Science' (Prieur-Richard, Walsh and Craig, 2019), which highlights six topical
51 research areas where more evidence is needed to inform action: finance; informality; uncertainty; urban
52 planning and design; built and green/blue infrastructure; and sustainable consumption and production. These
53 areas are addressed in specific sections of this chapter or as cross-cutting themes. The Cross-Working Group
54 Box provides a linkage with perspectives from Working Group III.

55

56 6.1.3 Terminology and Definitions

57

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 1 This chapter covers both `cities and settlements' and `key infrastructure'.

 2

 3 Definitions of `urban' have become more nuanced since the AR5 review with the publication of the OECD
 4 report `A new perspective on urbanisation' (OECD and European Commission, 2020). This report presents
 5 two new global definitions of urbanisation reflecting the degree of urbanisation on a continuum of cities,
 6 towns & semi-dense areas, and rural areas. The OECD estimates almost half the world's population (48%)
 7 live in cities, while just 24% live in rural areas and 28% live in towns & semi-dense areas (28%). In addition,
 8 the OECD report defines metropolitan areas as functional urban areas together with their surrounding
 9 commuting zones `to capture the full extent' of a city's working population. Metropolitan areas account for
10 54% of total world population, with the OECD estimating that commuting zones representing 17% of the
11 overall metropolitan population, rising to 31% in high-income countries. In the context of these global
12 definitions, this chapter identifies `cities and settlements' as concentrated human habitation centres (along a
13 dynamic continuum from rural to urban (Murali et al., 2019; Ward and Shackleton, 2016) (Figure 6.1) and
14 that are fundamentally inter-connected to other urban centres and rural areas as nodes within broader
15 networks.

16

17 Key infrastructure is used here to refer to `critical nodes and arteries' that comprise urban energy, food,

18 water, sewerage, health, transport and communication systems (Steele and Legacy, 2017; Maxwell et al.,

19 2018; Bassolas et al., 2019). Key or critical infrastructure provides much of the material basis of cities and

20 settlements, as well as the mechanisms for enabling flows of people, goods, data, waste, energy (through

21 urban metabolism processes of consumption and production) and capital, between urban regions and rural

22 areas (Blay-Palmer et al., 2018; Dijst et al., 2018). An overview of this process of `planetary' urbanization is

23 provided in Box 6.1. The balance of accumulated scientific knowledge on climate risks, impact and

24 adaptation has been generated from studies in large and medium sized cities of 1 million or more. While

25 these larger cities continue to grow rapidly (UNDESA 2018), settlements of more than 5 million people

26 contain less than a quarter of the world's urban population, and more than half of the world's urban residents

27 live in settlements of 1 million or less (Table 6.1). There is a key gap in knowledge, especially concerning

28 urban enabling environments and how smaller settlements can be supported to accelerate equitable and

29 sustainable adaptation in the face of financial and governance constraints (Birkmann et al., 2016; Shi et al.,

30 2016; Dulal, 2019; Rosenzweig et al., 2018b).

31

32

33 Table 6.1: Proportion of the urban population in different size class urban areas (UN-DESA 2018). Each column
34 indicates the percentage of urban residents in that region living in cities of that size class.

    Proportion (by region)  Africa Asia   Latin America      Europe  Northern  Oceania World
    of urban population                   and the Caribbean          America
    living in cities with
    population size:

    10 million +            8         15  17                 4       10        0      13

    5-10 million            6         9   3                  5       17        0      8

    1-5 million             22 22         25                 16      30           60  22

    500,000-1 million       9         10  8                  11      13           2   10
    300,000-500,000
                            6         6   6                  8       7            11  6

         Under 300,000      48 38         40                 57      24        27     41

35
36

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 1

 2 Figure 6.1: Defining `urban' and `rural' in relation to cities and settlements

 3

 4

 5 The chapter takes a comprehensive approach to understanding `key infrastructure' as expressed in social,
 6 nature-based and physical infrastructure. Social infrastructure includes the social, cultural, and financial
 7 activities and institutions as well as associated property, buildings and artefacts and policy domains such as
 8 social protection, health and education that support wellbeing, public life (Frolova et al., 2016; Latham and
 9 Layton, 2019). Nature-based infrastructure focusses on solutions to risk applying natural assets such as trees
10 or open water, physical infrastructure describes engineering approaches. Grey/physical infrastructure refers
11 to engineered assets that provide one or multiple services required by society, such as transportation or
12 wastewater treatment ((IISD, N.D.); see also IPCC glossary).

13

14 This approach is based on a framing of cities and settlements as complex systems where social, ecological
15 and physical processes interact in planned and unplanned ways. The chapter therefore builds on the AR5
16 chapter 10 conception of key economic sectors and services (e.g. energy, water, transport, waste, sanitation
17 and drainage) by positioning these within three major categories of infrastructure: social, nature-based and
18 physical (see Section 6.3). Where adaptation challenges can be responded to by more than one approach,
19 sometimes working together, this is noted (see also Chapter 17.2; 17.4). This approach allows an
20 understanding of adaptation that is not constrained to the administrative boundaries of cities and settlements,
21 but that includes the networks and flows that connect peri-urban communities, metropolitan regions,
22 suburban settlements and more rural places (See Box 6.1). Both formal provision of infrastructure services
23 by government and informal provision by communities and individuals are considered at risk from climate
24 change as are existing adaptation pathways and actions.

25

26 Cities are complex entities where social, ecological and physical systems interact in planned and unplanned
27 ways (Markolf et al., 2018). The complexity of cities, settlements and key infrastructure (Figure 6.2) where
28 multiple functional systems continuously interact, makes it difficult to distinguish risks (Box 6.1). The
29 literature often resolves this by offering discrete assessments for specific sectors (see Section 6.3). This
30 fragmented approach to understanding climate change associated impacts and risks is then reflected also in
31 siloed approaches to risk management and adaptation financing (see Section 6.4). Recent literature notes that
32 resilience planning has begun to overcome this tendency by presenting climate change impacts, losses and
33 damages, and urban processes, as unfolding together in interacting and cascading pathways (Fraser et al.,
34 2020; Eriksen et al., 2020) (Figure 6.2). The chapter reflects this change in the literature by presenting
35 climate change impacts through a series of risk assessments, including by hazard type, through indirect
36 impacts on: health or food security, key infrastructure systems, land-use and human mobility; water flows
37 and on structural conditions, like poverty and justice in the city (see Sections 6.3 and 6.4). In a departure

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 1 from AR5 we also consider the consequential interactions of climate risks, impacts, adaptation and climate
 2 mitigation (see also Cross Working Group Box URBAN in Chapter 6).

 3

 4 The IPCC 1.5°C Special Report commented that "The extent of risk depends on human vulnerability and the
 5 effectiveness of adaptation for regions (coastal and non-coastal), informal settlements, and infrastructure
 6 sectors (energy, water, and transport) (high confidence)" (Masson-Delmotte and Waterfield, 2018).We take
 7 this statement as a starting point for assessing the risks to cities, settlements and key infrastructure, with
 8 infrastructure extended as noted above. Risks from climate change are understood as the product of climate
 9 change associated hazards impacting on exposed and vulnerable people and assets (including biodiversity).
10 Adaptation can in some cases reduce exposure and susceptibility and enable recovery and scope for
11 transformation towards long-term equitable and sustainable development. Risks describe both present
12 conditions and also future prospects. Direct attribution of hazards to climate change remains limited to
13 temperature extremes and sea-level rise, though we consider all hydrometeorological hazards as systems
14 associated with climate change processes.

15

16

17

18 Figure 6.2: The interconnected nature of cities, settlements and infrastructure.

19

20

21 The chapter also assesses conditions supporting incremental and transformative adaptation (6.4). Incremental
22 and transformative adaptation are both important but serve distinct roles in the interaction of urban systems,
23 climate risk and risk management and in advancing social justice, just-transitions and climate resilient
24 development (see 6.4). Climate resilient development pathways are an emerging concept in literature since
25 the AR5 (Schipper et al., 2020). Climate resilient development is an iterative process of systemic change that
26 integrates both mitigation and adaptation efforts (see Glossary). Initial studies highlight the way rapid
27 urbanization and precarious urban housing and land tenure can undermine climate resilient development
28 while human settlements that are managed to protect housing tenancy and land tenure rights, can advance
29 land-use planning and social learning while reducing inequalities, and vulnerability, and enhancing resilient
30 development (Mitchell, Enemark and Van der Molen, 2015; Bellinson and Chu, 2019; Ürge-Vorsatz et al.,
31 2018). The benefits of integrating decision-making across scales for climate resilient development is also

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 1 highlighted in 6.4. How households engage with communities and neighbourhoods and larger units within
 2 cities and how cities (both formal and informal) interact with sub national and national actors is also
 3 discussed as is the role of finance, and CBOs/NGOs in the governance process.

 4

 5 6.1.4 Global Urban Trends

 6

 7 Since AR5, many cities and other settlements, particularly unplanned and/or informal in Asia and Africa,
 8 have continued to grow at rapid rates (van den Berg , Otto and Fikresilassie 2021). Elsewhere, in Latin
 9 America in particular, while growth is less rapid, inequality persists. As a result, cities and settlements are
10 crucial both as sites of potential action on climate change, and sites of increased exposure to risk (medium
11 evidence, high agreement).

12

13 Patterns and trends for urban population growth were described in detail in AR5. Between 2015 and 2020,
14 urban populations globally have grown by more than 397 million people, with more than 90 percent of this
15 growth taking place in Less Developed Regions (UNDESA, 2018). The latest population projections from
16 UNDESA (2018) reinforce the trends identified previously, with even higher estimates for global urban
17 populations. The 2012 data used in AR5 projected a global urban population of 4,984 million in 2030 and
18 6,252 million in 2050; the 2018 revisions project 5,167 million and 6,680 million respectively. Particularly
19 noteworthy is the higher projection provided for sub-Saharan Africa's urban population: increasing from 596
20 million to 666 million in 2030, and from 1,069 million to 1,258 million in 2050. These figures highlight the
21 continued trend towards larger urban populations, and the particular significance of this in areas which
22 currently have relatively small proportions of their populations living in towns and cities ­ this is also true in
23 some Small Island States (e.g. Solomon Islands) (McEvoy et al., 2020). The proportion of the global urban
24 population living in megacities (with populations of more than 10 million people) is expected to continue
25 growing slowly (to 16% of the urban total, or 862 million people, living in 48 agglomerations) by 2035
26 (UNDESA, 2018). The size and form of these megacities presents particular challenges with climate change
27 impacts, in areas including air quality (Baklanov, Luisa and Molina, 2016), flooding (Januriyadi et al., 2018),
28 and temperature increase (Darmanto et al., 2019) (see 6.2.3).

29

30 While there are few analyses of urban trends at the global scale, an additional 2.5 billion people are projected
31 to be living in urban areas by 2050, with up to 90 percent of this increase concentrated in the regions of Asia
32 and Africa, particularly in India, China and Nigeria where 35 percent of this urban growth is projected to
33 occur (UNDESA, 2018). Growth rates are slowing down in North America, South America and Europe
34 (UNDESA, 2018). Much global growth continues to outstrip the ability of governments or the private sector
35 to plan, fund and provide for sustainable urban infrastructure and this is most marked in low-income and
36 informal settlements (Angel et al., 2016). Rural migration as a driver of urbanisation is discussed in 6.2.4.3,
37 and literature has documented the way urban expansion, and the conversion of agricultural land is also
38 driven by investment incentives and weak planning policies (Colsaet, Laurans and Levrel, 2018;
39 Woodworth and Wallace, 2017). At the same time, early evidence suggests that ­ at least in some locations ­
40 out-migration from cities occurred as a result of the COVID-19 pandemic (Rajan, Sivakumar and Srinivasan,
41 2020) but the evidence is not clear and in some cases may have increased migration to other megacities
42 (Chow et al., 2021). There is also growing recognition that poor planning has exacerbated the concentrated
43 of deprivation in specific locations deepening a cycle of exclusion and marginalization (UNDESA, 2020).

44

45 One critical element of global urban trends, which has received growing attention is informality (see also
46 Prieur-Richard, Walsh and Craig, 2019). Informality is one of the key defining features of cities and
47 settlements in the Global South (See Glossary; Banks, Lombard and Mitlin, 2020; Myers, 2021;
48 UNHABITAT, 2016). In almost all nations in the Global South, more than half the urban workforce work in
49 informal employment; the proportions are particularly high in South Asia (82 percent in informal
50 employment) and sub-Saharan Africa (66 percent) (Chen, Roever and Skinner, 2016; Chen, 2014). The term
51 `informal settlement' refers to urban settlements or neighbourhoods that developed outside the formal system
52 that is meant to record land ownership and tenure and without meeting a range of regulations relating to
53 planning and land use, built structures and health and safety. Informality is a broader concept than `slums',
54 which are usually defined using measures of housing quality, provision of services and overcrowding. While
55 most countries do not generate formal statistics on the number of people living in informal settlements, UN
56 Habitat provides regional and global estimates of the number of urban households that are `slum' households
57 and therefore likely to include most residents of informal settlements. These estimates suggest that there

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 1 were 1034 million slum dwellers in 2018, including some 56 per cent of the urban population in sub-Saharan
 2 Africa and more than 30 percent of the urban population of South Asia (UN-Habitat, 2020). Informality is
 3 particularly important in understanding climate risks and responses in cities and settlements, and also in
 4 relation to key infrastructure (Trundle, 2020; Taylor et al., 2021).

 5

 6 Evidence since AR5 confirms that occupants of informal settlements are particularly exposed to climate
 7 events given low-quality housing, limited capacity to adapt, and limited or no risk-reducing infrastructure
 8 (high confidence) (Melore and Nel, 2020; Twinomuhangi et al., 2021; Satterthwaite et al., 2020; Patel et al.,
 9 2020a)(see 6.2 and case study). The impacts of COVID-19 are also increasingly impacting high-density
10 informal and slum settlements where social distancing and access to water for handwashing are limited
11 (Bhide, 2020; Pinchoff et al., 2021; Tagliacozzo, Pisacane and Kilkey, 2021; Wilkinson, 2020). This
12 compounds pre-existing vulnerability to climate change associated hazards. Box 6.1 expands on trends in
13 informality as part of global urbanism, peri-urbanization and suburbanization with implications for the global
14 distribution of climate risks and adaptive capacity.

15

16

17 [START BOX 6.1 HERE]

18

19 Box 6.1: Planetary Urbanisation and Climate Risk

20

21 The scale, reach, and complexity of contemporary urbanization compounds climate risks and conditions
22 adaptation (high confidence) (Miller and Hutchins, 2017; Rosenzweig et al., 2018b). Urbanization manifests
23 as a heterogeneous and plural process with varied spatial manifestations (Oswin, 2018) that extends beyond
24 cities and settlements, defining actions elsewhere in what has been called `planetary urbanization' (Brenner,
25 2014b). While the concept of Planetary urbanisation is contested for example for a predominantly
26 Eurocentric focus (Vegliň, 2021) the concept has reflected human urbanisation as a mega-trend of urban
27 expansion and landuse intensification (Capon, 2017; Lauermann, 2018). Three dimensions of planetary
28 urbanization are currently shaping adaptation actions: the new forms and scales of urbanization, the blurring
29 of boundaries around clearly demarcated territories, and the fragmentation of the urban hinterland into units
30 that serve productive functions for the reproduction of urban space under capitalism (Brenner and Schmid,
31 2017).

32

33 Planetary scale urbanization challenges current understandings of spatial settlements and how risk affects
34 urban communities (limited evidence, medium agreement) (Ruddick et al., 2018). Massive urbanization
35 manifests in large agglomerations such as metropolitan areas and urban regions, conurbations with unique
36 risk challenges, particularly when interacting with other drivers of vulnerability (Adetokunbo and Emeka,
37 2015; Maragno, Pozzer and Musco, 2021). Experiences of regional collaboration to scale adaptation to
38 metropolitan areas have shown to be effective, particularly facilitating information and technology
39 exchanges and institutional cooperation (Shi, 2019; Lundqvist, 2016), but may face challenges such as
40 addressing administrative and fiscal requirements and enrolling local populations in a meaningful
41 participation process (Shi, 2019). For example, the coordination of planning policies in the Vienna-
42 Bratislava metropolitan region, further divided by an international border, demonstrates that institutional
43 coordination alone is not sufficient to deliver effective spatial governance: instead, meaningful spatial
44 policies required the involvement of multiple actors (Patti, 2017). In addition to institutional coordination,
45 adaptation in rapidly urbanizing areas requires understanding how these processes magnify risk and
46 condition urban responses (see also 6.3).

47

48 Urban expansion processes affect human settlements everywhere, regardless of their size. Figure 6.1
49 represents a continuum of settlements from high to low-density areas (Ward and Shackleton, 2016). Urban
50 and rural areas are not always clearly differentiated (Brenner, 2014a; Brenner and Schmid, 2017). For
51 example, in 2010/2011, drought-exacerbated wildfires across Russia's agricultural hinterland not only led to
52 increased air pollution in Moscow and other large cities in the region it also disrupted global supply chains of
53 wheat and caused skyrocketing global food prices (Zscheischler et al., 2018). Floods in Bangkok, Thailand,
54 in 2011 destroyed many foreign-owned factories, leading to a global shortfall in different types of IT
55 equipment (Levermann, 2014).

56

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 1 Rural areas provide ecosystem services that benefit cities directly including thorugh reducing hazard (run-
 2 off, and temperature) and thorugh carbon storage ­ and can be maintained through urban markets and other
 3 inputs (Gebre and Gebremedhin, 2019). Most urban areas extend into dispersive peri-urban areas where
 4 urban and rural land uses coexist (Simon, 2016) and/or suburban areas which are lower density and primarily
 5 residential in function. Moreover, the urban and rural differentiation creates normative expectations at the
 6 heart of planning conflicts and constraints urban governance (Taylor, Butt and Amati, 2017). Expanding
 7 peri-urban areas pose specific structural constraints to addressing risks. In Bogotá, Colombia, a study found
 8 marked inequalities as more impoverished families had restricted access to peri-urban forests, trees, and tree
 9 services (Escobedo et al., 2015). Factors like limited land ownership and tenure insecurity in peri-urban areas
10 hinder people's ability to invest in permanent infrastructure to buffer themselves from flood events, as
11 witnessed in the slums in Nairobi (Thorn, Thornton and Helfgott, 2015). Building resilience and adaptation
12 via community mobilization may not be effective in peri-urban areas shaped by migration, agricultural
13 intensification, and industrialization (Wandl and Magoni, 2017).

14

15 At the same time, actions to improve access to peri-urban services almost always improve resilience (Simon,
16 2016) Evidence from Kampala, Addis Ababa, Dar es Salaam, Douala, Ibadan, Nairobi, Dakar and Accra
17 shows that urban and peri-urban agriculture and forestry can support adaptation (Lwasa et al., 2014). In the
18 metropolitan area of Milan, multifunctional agriculture supports a local, more sustainable food chain
19 (Magoni and Colucci, 2017). Since communities in peri-urban areas are often transitory, efforts towards
20 creating social capital by promoting civic engagement are crucial to facilitate collective action (Narain et al.,
21 2017). For example, adaptation actions can help to build the capacity of the community to engage with
22 service providers (Harris, Chu and Ziervogel, 2018; Ziervogel et al., 2017), as demonstrated in parts of peri-
23 urban Kolkata, India, and Khulna, and Bangladesh (Gomes and Hermans, 2018; Gomes, Hermans and
24 Thissen, 2018).

25

26 Urbanization on an immense scale blurs the boundaries that previously defined cities and settlements
27 (Arboleda, 2016a; Shaw, 2015; Brenner, 2014a; OECD and European Commission, 2020; Schmid, 2018;
28 Davidson et al., 2019; Wu and Keil, 2020). For example, peri-urban areas typically extend over multiple
29 government jurisdictions (Wandl and Magoni, 2017). Adaptation actions can be difficult to plan, coordinate,
30 implement and evaluate in these transboundary contexts (Solecki et al., 2018; Srivastava, 2020; Fünfgeld,
31 2015; Rukmana, 2020; Carter et al., 2018). In Medellín, Colombia, a 46-mile-long green belt is being built to
32 stop urban expansion while also protecting urban forests, providing access to green spaces, and reducing
33 urban heat island effects (Anguelovski et al., 2016). However, large-scale infrastructure projects like this one
34 require coordination between regional transport authorities and the different municipalities in charge of
35 housing and public services, in addition to consulting communities on their social impact (Chu, Anguelovski
36 and Roberts, 2017). Local and regional authorities have competing mandates ­ such as a competition for
37 taxpaying residents in peri-urban, commuting zones ­ and different infrastructure investment logics, political
38 drivers, and constituent needs. Smaller discrete infrastructure projects that actively engage local populations
39 may provide better opportunities to build resilience across fragmented spaces (Santos, 2017; Kamalipour and
40 Dovey, 2020).

41

42 Suburbanization follows a gradual movement of citizens from high-density urban centres to the suburbs
43 (Pieretti, 2014). Suburbanization generates new ways of appropriating space where, again, inequality (both
44 in terms of limited access to access and limited capacity to respond to external changes) seems to be the
45 main driver and a magnifier of its impacts (Keil and Macdonald, 2016). The development of enclaves for
46 higher-income people, that appropriate resources and constraint the access to those resources for
47 disadvantaged populations has been recorded in places as distant as Santiago de Chile, People's Republic of
48 China, India, Indonesia, or the Philippines (Calvet and Castán Broto, 2016; Phelps, Miao and Zhang, 2020;
49 Bulkeley, Castán Broto and Edwards, 2014; Buchori et al., 2021; Kleibert, 2018). The appropriation of land
50 and resources in enclaves defends exclusive, privileged communities at the expense of everyone else.
51 Enclaves exacerbate inequalities because those who cannot afford to live in the enclave suffer the
52 fragmentation of public services, restrictions in access to resources, and greater exposure to climate risks
53 (Hodson, 2010; Haase et al., 2017a). Moreover, suburbanization is linked to the privatization of public
54 spaces and the decline of public infrastructures, collective spaces, and green projects (Long and Rice, 2019;
55 North, Nurse and Barker, 2017). Climate gentrification, whereby vulnerable communities are displaced from
56 urban areas with lower climate risks (UN-Habitat, 2020), reconfigures urban areas, for example, as higher-
57 income populations move away from the city centers, as shown in North American cities that have already

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 1 suffered climate-related impacts such as Miami, Philadelphia and New Orleans (Keenan, Hill and Gumber,
 2 2018; Shokry, Connolly and Anguelovski, 2020; De Koning and Filatova, 2020; Aune, Gesch and Smith,
 3 2020).

 4

 5 Urbanization leads to the spatial fragmentation of the hinterland, divided alongside functional units to serve
 6 the demands of the capitalist urban economy (Brenner and Schmid, 2017). Urbanization is thus linked to new
 7 intensities of resource exploitation that threaten vulnerable land and ecosystems, as shown in the Amazon
 8 and that extend across scales (Arboleda, 2016b; Wilson, 2018). The fragmentation of the hinterland for
 9 extractivist purposes depletes ecosystem services and further exacerbates cascading risks (high confidence)
10 (Section 6.2.6).

11

12 [END BOX 6.1 HERE]

13

14

15 Adaptation and related concepts of urban climate resilience are also concerns for the broader agenda of
16 sustainable development (Wachsmuth, Cohen and Angelo, 2016). Urban areas can play a positive role in
17 advancing sustainability, but the pace and scale of urban development can also undermine progress in SDGs
18 (Barnett and Parnell, 2016; Maes et al., 2019; Anarfi, Hill and Shiel, 2020) (high confidence). With careful
19 planning, urbanization can be a transformative force, enhancing equity and wellbeing through co-benefits
20 and synergies between climate change adaptation, equitable urban development and mitigation (medium
21 evidence, medium agreement) (Parnell, 2016a; Solecki et al., 2015; Sharifi, 2020). Cities can be effective
22 change agents when supported by networked local and national institutions including professional bodies
23 (high confidence) (Andonova, Hale and Roger, 2017; Brandtner and Suárez, 2021; Heidrich et al., 2016;
24 Kern, 2019; Farzaneh and Wang, 2020). Low Emission Development Strategies (LEDS) have developed
25 effective science-policy interaction to support energy system, environmental, and economic development
26 planning strategies in the city of Shanghai, China (Farzaneh and Wang, 2020). New literature is emerging
27 about how adaptive changes at the urban level could integrate both far reaching rapid emission reduction and
28 community protection in transformative ways (Wamsler and Raggers, 2018; Rosenzweig and Solecki, 2018;
29 UN-Habitat, 2020; Ziervogel, 2019a). There is an increasing consensus about the need for integrated
30 governance of urban areas within and across regions, so that urban risk management and adaptation happen
31 hand in hand with more general processes of transition towards more sustainable urban regions (Simon,
32 2016; UN-Habitat, 2020).

33

34 Since AR5 there has also been increasing recognition of the contribution of diverse knowledges including
35 local and Indigenous knowledge in contributing to the development and interpretation of urban relevant
36 climate change data and policy for effective action (Klenk et al., 2017; Hosen, Nakamura and Hamzah, 2020;
37 Makondo and Thomas, 2018). Indigenous and local knowledge inform coping strategies in urban adaptation
38 planning and new directions for action (Nakashima, Krupnik and Rubis, 2018; Abudu Kasei, Dalitso
39 Kalanda-Joshua and Tutu Benefor, 2019). Indigenous and local knowledge is also found to shape perceptions
40 about urban climate risk awareness, its acceptable limits, causation and preferences for adaptation (see also
41 Pyhälä et al., 2016 for a review; see Jaakkola, Juntunen and Näkkäläjärvi, 2018 for impacts on Indigenous
42 peoples in the EU; Saboohi et al., 2019). Local perceptions about climate change in turn influence adaptation
43 behaviours in settlements and urban communities (Lee et al., 2015; Larcom, She and van Gevelt, 2019).
44 Engagement with Indigenous and local knowledge is an enabling condition for planning community-
45 appropriate climate adaptation responses (Fernández-Llamazares et al., 2015). Urban decision-making that
46 includes Indigenous and local knowledge has co-benefits for addressing Indigenous dispossession, historical
47 inequities and marginalization of Indigenous values that occurred (Parsons et al., 2019; Carter, 2019;
48 Maldonado et al., 2016; Orlove et al., 2014; Pearce et al., 2015). Indigenous and local knowledge can help
49 deliver culturally appropriate strategies and local choices for urban risk management through, for example
50 community-based observation networks (Alessa et al., 2016), integrating ecosystem-based adaptation
51 strategies in institutional structures (Nalau et al., 2018), using Multiple Evidence-Based Approaches (Tengö
52 et al., 2014), and adopting forms of governance that centre Indigenous peoples in urban adaptation and
53 decision making (Horn, 2018; Parsons, Fisher and Nalau, 2016).

54

55 6.1.5 Changes in the Global Enabling Environment

56

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1 This section reports on changes in global enabling environment ­ the architecture of international agreements
2 available to inform policy for national governments and others on urbanization and climate adaptation, since
3 the AR5.

 4

 5 Six new international agreements and initiatives have been achieved, each of which has far-reaching
 6 implications for the management of rapid urbanization and climate change: the Paris Climate Agreement
 7 (United Nations, 2015b); the 2030 Agenda for Sustainable Development including the Sustainable
 8 Development Goals (United Nations, 2015c); the Sendai Framework for Disaster Risk Reduction (UNISDR,
 9 2015); the New Urban Agenda (United Nations, 2016a); Addis Ababa Action Agenda (July 2015) and the
10 World Humanitarian Summit (May 2016). Table 6.2 summarises these.

11

12

13 Table 6.2: International policy agreements with implications for urbanization and climate adaptation

    Agreement        Scope of agreement      Relevance for cities, settlements Relevance for addressing climate
    (date of
    agreement)                               and infrastructure                 change risk

    Sendai           Global agreement for    Identifies rapid urbanization as a Highlights the need to respond to
    Framework for
    Disaster Risk    reducing disaster risks in all key underlying risk factor for systemic risk, including compound
    Reduction
    (March 2015)     countries and at all levels. disasters and driver of resilience. and cascading risks and impacts

                     Highlights urbanization as a Promotes shift from disaster from natural, technological and

                     key driver of risk and  response to disaster risk          biological hazards. Includes focus on

                     resilience.             management & reduction             chronic stressors and sudden shocks

                                             through cooperation between through governance, planning,

                                             national and local governments. disaster response, post-event

                                             Limited focus on the role of civil recovery.

                                             society.

    Addis Ababa      Global agreement arising Includes general comments on      Financing a critical element of risk
    Action Agenda                                                               reduction in cities and settlements
    (July 2015)      from the International  the importance of local actors     (see section 6.4).
                                                                                Underlying variability of
                     Conference on Financing and recognises the need for        institutional arrangements inhibits
                                                                                development of universal
                     for Development (United strengthening capacities of        framework.

                     Nations, 2015a)         municipal and local

                     emphasized the need for governments.

                     adequate financing at all Commits to "support" local

                     levels of government,   governments to "mobilise

                     especially sub-national and revenues as appropriate".

                     local, to support sustainable Offers little on how to get

                     development, infrastructure finance to support local

                     and climate mitigation  governments addressing these

                     (UN-Habitat, 2016b).    commitments.

    Transforming     Global agreement adopted SDG11 speaks explicitly to        SDG13 on climate action requires
    our world: the
    2030 Agenda      by 193 governments that making cities "inclusive, safe, action in cities and settlements.
    for Sustainable
    Development      includes the 17 Sustainable resilient and sustainable".    Integrated approach can address
    (September
    2015)            Development Goals       Extensive reference to universal underlying drivers of risk.

                     (SDGs)                  provision of basic services in

                                             other SDGs which will require

                                             substantial efforts in cities;

                                             equality and governance are also

                                             stressed.

                                             Focuses on national goals and

                                             national monitoring with

                                             insufficient recognition of key

                                             roles of local and regional

                                             governments and urban civil

                                             society in addressing most of the

                                             SDGs.

    The Paris        Global agreement under References the role of the local    Encourages cities to develop specific
    Agreement        UN Framework Convention or sub-national levels of          agendas for climate action
    (December        on Climate Change: signed government and cities as non-    (mitigation and adaptation).
    2015)            by 194 and ratified by 189 state actors.
                     member states (05/01/21)

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The World       Not an agreement, but a Includes five agreed `core         Climate change likely to shape flows
Humanitarian
Summit          summit of 180 member responsibilities' with relevance of refugees and migrants who are
(May 2016)
                states generating over 3,500 for urban areas, and          likely to live in highly exposed

                commitments to action & commitments were made by areas, particularly in low-income

                addressing the role of non- professional associations, non- cities. However "meagre funding for

                state actors in reducing risk governmental organizations and collaboration, poor data collection

                of climate change related networks of local authorities to and sharing" (Acuto, 2016) limits

                forced-displacement of address these in towns and cities. commitment effectiveness

                people                                                     (Speckhard, 2016).

The New Urban   Global agenda adopted at Intended as the global guideline  Clearly frames roles for cities within
Agenda                                                                     national and international systems in
(October 2016)  UN Conference on Housing for sustainable urban             contributing to sustainability
                                                                           (including low-carbon development)
                and Sustainable Urban development for 20 years,            and resilience (including
                                                                           adaptation). Frames the role for
                Development (Habitat III) seeking to provide coherence     cities within national and
                                                                           international systems, including an
                Envisioned national urban with other agreements. Focus on  ongoing assessment of their
                                                                           contribution to sustainability and
                policies and adaptation national policy and action.        resilience (Kaika, 2017; Valencia et
                                                                           al., 2019)
                plans as a central device to Limited recognition of urban

                inform subnational  governments or civil society as

                governments addressing initiators and drivers of change.

                sustainable development. .

 1

 2

 3 Alongside new international agreements are a series of new landmark global stocktake reports: three IPCC
 4 special reports including the IPCC 1.5 report (Pörtner et al., 2019; Shukla et al., 2019; Hoegh-Guldberg et
 5 al., 2018), the UN Environment GEO6 (UN Environment, 2019), IPBES 2019 (Brondizio et al., 2019), and
 6 UNDRR 2019 (UNDRR, 2019), each have argued for urgent action on climate mitigation and to invest in
 7 inclusive strategies for adaptation if the Sustainable Development Goals are to be met. These findings are
 8 comprehensively evidenced and do not need to be revisited here. Our starting point then is to assess the
 9 science on how inclusive, sustainable development can be delivered through enhanced adaptation to climate
10 change risks.

11

12 As a blueprint for advancing human dignity, the Sustainable Development Goals emphasize the need to
13 consider how to achieve a better and more sustainable future while `leaving no one behind.' In doing so, they
14 highlight an agenda focused on wellbeing, equality and justice. The objective for SDG11 is defined as:
15 "Make cities and human settlements inclusive, safe, resilient and sustainable" with ten associated targets
16 including ensuring access for all to adequate, safe and affordable housing and basic services; participatory
17 planning; safeguarding heritage features; reducing disasters particularly water related disasters and economic
18 impacts on the poor; and promoting resource efficiency, mitigation and adaptation to climate change,
19 resilience to disasters, and develop and implement plans, in line with the Sendai Framework for Disaster
20 Risk Reduction. Similarly SDG9 aims to build resilient infrastructure, promote inclusive and sustainable
21 industrialization and foster innovation, with associated targets. The IPCC 1.5 special report emphasized that
22 there are often cobenefits in pursuit of SDGs and adaptation strategies where "well-designed mitigation and
23 adaptation responses can support poverty alleviation, food security, healthy ecosystems, equality and other
24 dimensions of sustainable development" (Masson-Delmotte et al., 2018 FAQ 5.1). However there may also
25 be negative trade-offs for example between pursuit of growth and reducing climate change risk (International
26 Council for Science, 2017; Masson-Delmotte et al., 2018 Executive Summary; Roy et al., 2018).

27

28 The Paris Agreement also envisioned a significantly more active role for cities and other non-state actors in
29 facilitating policy change (Hale, 2016) including through participation in Nationally Determined
30 Contributions (NDCs), although there is little systematic review of the contributions made by cities to NDCs
31 (Hsu et al., 2020; Bäckstrand and Kuyper, 2017). Over two-thirds ­ 113 out of 164 ­ of initial Intended
32 Nationally Determined Contributions, prior to ratification, had referenced urban responses in the context of
33 sustainable development, climate mitigation and adaptation (UN-Habitat, 2016a). Analysis of those INDCs
34 revealed 58 focused on urban climate adaptation, 17 focused on both adaptation and mitigation, and 4
35 focused on mitigation (UN-Habitat, 2017). Simultaneously, multiple efforts have emerged to align the
36 actions of nation states with those of other actors, including the UNFCC 2014 Global Climate Action Portal
37 (Hsu, Weinfurter and Xu, 2017). While significant optimism has been gathered around the possibility to

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 1 intervene at subnational level, the most difficult challenge has been to establish a coherent view of the
 2 overall contribution that cities and settlements are making (Hale, 2016; Chan et al., 2015b). Although
 3 meeting the Paris goals will require staying within a `carbon budget', supporting rapidly developing urban
 4 areas in the Global South to the same infrastructure level as developed cities, may consume significant
 5 proportions of that budget (Bai et al., 2018).

 6

 7 There is increasing international effort amongst non-Party stakeholders to the Paris Climate Agreement to
 8 collaborate to meet the Paris Climate goals (Data Driven Yale New Climate Institute PBL, 2018; Chan et al.,
 9 2015a). A review of contributions by non-state actors in 2019 by the EU Covenant of Mayors identified
10 10427 cities with climate commitments, while the Global Covenant of Mayors included 10543 cities
11 representing a population of 969 million citizens (Palermo et al., 2020; Peduzzi et al., 2020). International
12 efforts also include the United Nations Framework Convention on Climate Change (UNFCCC) Non-State
13 Actor Zone for Climate Action (Data Driven Yale New Climate Institute PBL, 2018). There is also a
14 proliferation of new non-governmental and public-private actors that address both adaptation and mitigation
15 in cities and settlements, including: the C40 Cities Climate Leadership Group, 100 Resilient Cities; the
16 Global Resilient Cities Network, We Mean Business, and We Are Still In (Ireland and Clausen, 2019) and
17 the Global Alliance for Buildings and Construction (Dean et al., 2016). However, there is as yet limited
18 research into the effectiveness of these initiatives in enhancing medium and small city adaptation and limited
19 documentation of climate adaptation actions by non-traditional agents, particularly in the Global South
20 (Lamb et al., 2019).

21

22 New urban activists and stakeholders including youth, and Indigenous and minority communities and Non-
23 Governmental Organizations alongside business groups have also been visible in the global urban climate
24 debate, pressing for faster, more far reaching change (Frantzeskaki et al., 2016; O'Brien, Selboe and
25 Hayward, 2018; Alves, Campos and Penha-Lopes, 2019; Smith and Patterson, 2018; Crnogorcevic, 2019;
26 Campos et al., 2016; Hayward, 2021). Emergent urban social movements for climate justice often build on
27 established international networks including local activists such as Shack and Slum Dwellers International
28 while others are inspired by indigenous movements and are focused on human rights, indigenous sovereignty
29 and land claims, and access to water, intergenerational justice, and gender and youth movements coordinated
30 on social media (Agyeman et al., 2016; Cohen, 2018; Ulloa, 2017; Hayward, 2021; Prendergast et al., 2021).
31 The emergence of climate justice movements in urban communities has the potential to reframe policy
32 discussion in cities in ways that also bring inequality and climate justice to the fore (Sheller and Urry, 2016)
33 underscoring growing public calls for more far-reaching, transformative changes towards socially just urban
34 transformations (Akbulut et al., 2019; Foran, 2019; Vandepitte, Vandermoere and Hustinx, 2019; Smith and
35 Patterson, 2018).

36

37 This section demonstrates the consistency with which urban processes and places have been rising to the top
38 of international agreements and agendas in the last 10 years (Bulkeley, 2015; van der Heijden et al., 2018;
39 Knieling, 2016). However, many cities, particularly smaller cities and informal settlements in the Global
40 South where development is rapid, need greater support for local governance, more information, and more
41 diverse sources of finance to meet the vision of global climate agreements (Greenwalt, Raasakka and
42 Alverson, 2018; Cohen, 2019). Moreover, the response of many cities to climate change is often constrained
43 by wider political, social and economic structures, development path dependences and high carbon lock-in
44 (Princeti, 2016; Johnson, 2018; Jordan et al., 2015).

45

46

47 6.2 Impacts and Risks

48

49 This section assesses the impacts of hazards associated with climate change that will affect cities, settlements
50 and key infrastructure, particularly how climate systems and urban systems interact to produce patterns of
51 risk and loss. The conclusions of the IPCC Special Report on Global Warming of 1.5°C noted that "Global
52 warming of 2°C is expected to pose greater risks to urban areas than global warming of 1.5°C (medium
53 confidence)."

54

55 This section commences with a review of scenarios and pathways linking urban and infrastructural
56 development with climate change; then assesses the key risks (with a focus on those for which there is a
57 greater degree of evidence or confidence since AR5) and how these risks are created in urban settings. It then

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 1 assesses evidence on the differentiated nature of human vulnerability and the risks affecting key
 2 infrastructure. Finally, this discussion reviews compound and cascading risks, and risks created by
 3 adaptation actions.

 4

 5 6.2.1 Risk Creation in cities, settlements, and infrastructure

 6

 7 In addition to direct climate impacts, interactions between changing urban form, exposure and vulnerability
 8 can create climate change-induced risks and losses for cities and settlements. Climate change already
 9 interacts with on-going global trends in urbanization to create regionally specific impacts and risk profiles.
10 Through demographic change and encroachment into natural and agricultural lands and coastal zones,
11 rapidly expanding urban settlements can place new physical assets and people in locations with high
12 exposure (Tessler et al., 2015; Arnell and Gosling, 2016; Kundzewicz et al., 2014). Increasing rates of global
13 urbanization will pose additional challenges to areas that have high levels of poverty, unemployment,
14 informality, and housing and service backlogs (Jiang and O'Neill, 2017; Williams et al., 2019). There is
15 some evidence to suggest that climate change impacts themselves are increasing urbanization rates
16 generating a challenging feedback loop. In Sub-Saharan Africa, for example, manufacturing towns have
17 experienced growth due to population movement following droughts in agricultural hinterlands (Henderson,
18 Storeygard and Deichmann, 2017). The rapid rate of urbanization therefore presents a time-limited
19 opportunity to work towards risk reduction and transformational adaptation in towns and cities. The
20 following sections explore these dynamic interactions between urban systems and climate change, and how
21 these shape risk for people and for key infrastructures.

22

23 Examining projected climate change impacts and resulting risks in cities, settlements and key infrastructures
24 requires the prerequisite development of scenarios which are plausible descriptions of how the future may
25 develop based on a coherent and internally consistent set of assumptions about key driving forces, (e.g., rate
26 of technological change, prices and relationships) and pathways or the temporal evolution of natural and/or
27 human systems, such as demographic and urban land cover change, towards a future state or states ((Gao and
28 O'Neill, 2020; Gao and O'Neill, 2019); see also 6.1.5).

29

30 Climate change research creates scenarios integrating emissions and development pathways dimensions (Ebi
31 et al., 2014; van Vuuren et al., 2017b; van Vuuren et al., 2017a) and Representative Concentration Pathways
32 (RCPs) (Riahi et al., 2017). For risk reduction at regional scales, scenarios require urban-relevant climate
33 projections e.g. downscaling from global and regional climate models of variables such as temperature,
34 precipitation, air pollutants, and sea level rise that are analyzed usually for mid- or end-21st Century
35 timeframes (e.g. Mika et al., 2018; Kusaka et al., 2016; Masson et al., 2014b). These data are needed to
36 ascertain likely ranges of climate change impacts within city and settlement boundaries, and to quantify
37 physical exposure when developing pathways for risk reduction. Consideration of current and projected
38 future growth pathways of multiple urban sectors and key infrastructure e.g. transport, energy, and buildings,
39 are also needed to estimate probabilities of risk outcomes and damages within and across urban systems
40 (O'Neill et al., 2015)(WGIII AR6 Chapter 8).

41

42 The challenges of managing these risks are amplified by the complex interactions between climate and urban
43 scenarios, due to the smaller spatial-temporal scales of urban areas in climate change modelling relative to
44 Global Climate Models (GCM) and Shared Socioeconomic Pathways (SSP); geographical or
45 geomorphological variations in city location; uncertainties arising from incomplete assumptions about socio-
46 economic pathways at urban scales affecting urban demographics e.g. fertility rates and life expectancies, or
47 increased rural-urban migration; and challenges in modelling the urban climate and in developing urban
48 climate observational networks in cities (WGI Box 10.3; (Kamei, Hanaki and Kurisu, 2016; Yu, Jiang and
49 Zhai, 2016; Jiang and O'Neill, 2017; Baklanov et al., 2018). Additionally, carbon-intensive economic
50 growth, increasing inequalities, global pandemics, and uncontrolled or unmanaged urbanization will
51 exacerbate the exposure and vulnerability of urban systems modelled in existing climate scenarios and
52 pathways (high confidence) (Phillips et al., 2020a; Jackson, 2021; Raworth, 2017; Moraci et al., 2020).
53 Mitigating these outcomes requires new forms of urban governance for climate adaptation, disaster risk
54 reduction, and building resilience (see Section 6.4).

55

56 Strong connections exist between climate change scenarios and urban climate-related risks. In some cases,
57 the linkage is direct as climate change is associated with more frequent and more intense extreme weather

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 1 and climate events as assessed in Section 6.2.3. In other contexts, the connection is mediated by urban
 2 developmental pathways arising from local-scale environmental stresses and degradation, and access to
 3 adaptation options as reviewed in Section 6.2.4.

 4

 5 6.2.2 Dynamic Interaction of Urban Systems with Climate

 6

 7 Urban systems interact with climate systems in multiple, dynamic and complex ways (Section 6.1.1, WG1
 8 Box 10.3). Climate change can have direct impacts on the functioning of urban systems, while the nature of
 9 those systems plays a substantial role in modifying the effects of climate change (high confidence) (Frank,
10 Delano and Caniglia, 2017; Smid and Costa, 2018). An example of this urban system-climate nexus is the
11 urban heat island effect (discussed in in section 6.2.3.1) (Susca and Pomponi, 2020). Assessing the inter-
12 relationships between multiple systems and a range of hazards is particularly important, as many cities are
13 presently exposed to multiple climate-related hazards: more than 100 cities analyzed as part of a 571 city
14 study in Europe were deemed vulnerable to two or more climate impacts (Guerreiro et al., 2018). Rapid
15 expansion of urban areas increases the exposure of urban populations to various hazards independent of
16 global climate change. Huang et al. (2019) project that urban land areas will expand by 0.6­1.3 million
17 km2 between 2015 and 2050, an increase of 78%­171% over the urban footprint in 2015. Specifically in
18 relation to floods and droughts, Güneralp et al (2015a) calculate that even without accounting for climate
19 change, the extent of urban areas exposed to flood hazards will increase 2.7 times between 2000 and 2030,
20 the extent exposed to drought hazards will approximately double during this period, and urban land exposed
21 to both floods and droughts will increase more than 2.5 times.

22

23 This section assesses observed and expected impacts from the main hazards identified for cities, settlements
24 and infrastructure ­ temperature extremes (and the urban heat island), flooding (including sea-level rise),
25 water scarcity and security ­ as well as other hazards that are either less well-studied and/or likely to affect
26 only a limited number of locations. The data assessed in this section are limited by uneven coverage. Despite
27 improvements since AR5, data continue to be more complete for extreme events than for chronic hazards
28 and everyday risks - which may have high aggregate impacts and disproportionately erode the wellbeing of
29 urban poor households, especially for the most vulnerable, including women, children the aged, disabled and
30 homeless (van Wesenbeeck, Sonneveld and Voortman, 2016; Kinay et al., 2019; Connelly et al., 2018). Data
31 coverage is also less comprehensive for smaller settlements in poorer countries ­ the locations where urban
32 growth is often high and adaptive capacities are often low (e.g. Rufat et al., 2015). Thus, data gaps frequently
33 coincide with highly vulnerable populations (Rufat et al., 2015; Satterthwaite and Bartlett, 2017). Here, even
34 small changes in livelihoods, health, or representation and voice can rapidly bring households into positions
35 of risk, even when hazard conditions are relatively stable (Ziervogel et al., 2017). These structural limits in
36 available data are discussed also in chapters 7 (Health, wellbeing and the changing structure of communities)
37 and 8 (Poverty, livelihoods and sustainable development), and WGI Box 10.3. There are implications also
38 for Adaptation (Section 6.3) where the greater availability of evidence on exposure driven risk can limit
39 resilience building interventions that focus on the reduction of vulnerability.

40

41 6.2.2.1 Temperatures and the Urban Heat Island

42

43 Higher temperatures associated with climate change, through warmer global average temperatures and
44 regional heat wave episodes, will interact with urban systems in a variety of ways (WG1 Box 10.3). Future
45 urbanization will amplify projected local air temperature increase, particularly by strong influence on
46 minimum temperatures, which is approximately comparable in magnitude to global warming (high
47 confidence) (WG1 Box TS14). Within cities exposure to heat island effects is uneven with some populations
48 disproportionately exposed to risk including low income communities, children, the elderly, disabled, and
49 ethnic minorities ((Quintana-Talvac et al., 2021; Sabrin et al., 2020; Chambers, 2020) and see later in this
50 section).

51

52 The risks to cities, settlements and infrastructure from heat waves will worsen (high confidence) (Leal Filho
53 et al., 2021) see also 6.2.5; 6.3.3.1, WG1 Box TS14). Depending on the RCP, between half (RCP2.6) to
54 three-quarters (RCP8.5) of human population could be exposed to periods of life-threatening climatic
55 conditions arising from coupled impacts of extreme heat and humidity by 2100 (Figure 6.3; (Mora et al.,
56 2017b; Zhao et al., 2021)). Cities in mid-latitudes are potentially subject to twice the levels of heat stress
57 compared to their rural surroundings under all RCP scenarios by 2050 e.g. Belgian cities (Wouters et al.,

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1 2017). A disproportionate level of exposure exists in subtropical cities subject to year-round warm
2 temperatures and higher humidity, requiring less warming to exceed "dangerous" thresholds e.g. Nairobi
3 (Scott et al., 2017) and Săo Paulo (Diniz, Gonçalves and Sheridan, 2020). It is expected that more than 90%
4 of the 300 million people who will exposed to super- and ultra-extreme heatwaves in the Middle East and
5 North Africa will live in urban centres (Zittis et al., 2021), while the major driver for increased heat exposure
6 is the combination of global warming and population growth in already-warm cities in regions including
7 Africa, India and the Middle East (Klein and Anderegg, 2021).

8

9

10

11 Figure 6.3 Global distribution of population exposed to hyperthermia from extreme heat for the present (a), and
12 projections from selected Representative Concentration Pathways in (b.) mid-21st Century, and (c.) end 21st Century.
13 Shading indicates projected number of days in a year in which conditions of air temperature and humidity surpass a
14 common threshold beyond which climate conditions turned deadly and pose a risk of death (Mora et al., 2017b). Named
15 cities are top fifteen urban areas by population size during 2020, 2050, and 2100 respectively as projected by Hoornweg
16 and Pope (2017)

17

18

19 Locally, the urban heat island also elevates temperatures within cities relative to their surroundings. It is
20 caused by physical changes to the surface energy balance of the pre-urban site from urbanization, resulting
21 from the thermal characteristics and spatial arrangement of the built environment, and anthropogenic heat
22 release ((Oke et al., 2017; Chow et al., 2014; Susca and Pomponi, 2020); WGI FAQ10.1). A considerable
23 body of evidence exists on how the multi-scale impacts and consequent risks arise when local elevated
24 temperatures within settlements are enhanced by climate change, with specific elements of this affecting
25 megacities (Darmanto et al., 2019). The urban heat island itself is amplified during heat waves (Founda and
26 Santamouris, 2017), but the extent to which varies regionally and by time of day (Ward et al., 2016a; Zhao et
27 al., 2018b; Eunice Lo et al., 2020). When combined with warming induced by urban growth, extreme heat

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 1 risks are expected to affect half of the future urban population, with a particular impact in the tropical Global
 2 South and in coastal cities and settlements ((Huang et al., 2019); CCP2.2.2; Table CCP2.A.1).

 3

 4 Heat risk is associated with a range of health issues for urban residents, with the consequences of higher
 5 urban temperatures being unevenly distributed across urban populations (high confidence). Clear evidence
 6 exists of increased health risks to elderly populations in settlements, especially higher levels of mortality in
 7 elderly populations from urban heat island during heat wave events (Fernandez Milan and Creutzig, 2015;
 8 Taylor et al., 2015; Ward et al., 2016a; Heaviside, Macintyre and Vardoulakis, 2017; Gough et al., 2019; Xu
 9 et al., 2020a), while health and fitness variables are also major determinants of the effects of heat stress
10 (Schuster et al., 2017) (see also Table 7.2). Heat stress and dehydration are also related to behavioural and
11 learning concerns, with dehydration impairing concentration and cognition for both adults and children
12 (Merhej, 2019). Literature on pediatric heat exposure is associated with increases in emergency department
13 visits for heat-related illnesses, electrolyte imbalances, fever, renal disease, and respiratory disease in young
14 children (Winquist et al., 2016), with less severe outcomes such as lethargy, headaches, rashes, cramps, and
15 exhaustion negatively affecting children in school and play environments (Vanos, 2015; Hyndman, 2017).
16 Young children in cities are particularly sensitive to heatwaves, and may have little experience or capacity to
17 cope with heat extremes (Norwegian Red Cross, 2019). Such vulnerability of young children to heat is
18 compounded with projected urbanization rates and poor infrastructure, particularly in South Asian and in
19 African cities (Smith, 2019). There is evidence that socioeconomically disadvantaged populations are more
20 likely to live in hotter parts of cities associated with higher-density residential land-use in dwellings with less
21 effective insulation built with poorer or older construction materials (Inostroza, Palme and de la Barrera,
22 2016; Tomlinson et al., 2011). Specific emerging risks for occupational and related heat illnesses are found
23 in urban tropical or subtropical low-income and middle-income countries (Andrews et al., 2018; Green et al.,
24 2019).

25

26 There is an emerging risk of diminished indoor thermal comfort due to climate change, evidenced by
27 research into negatively affected thermal comfort indices and/or increased number of overheating hours
28 under future emissions scenarios (medium confidence) (e.g. Liu and Coley, 2015; van Hooff et al., 2014;
29 Vardoulakis et al., 2015; Dodoo and Gustavsson, 2016; Invidiata and Ghisi, 2016; Makantasi and
30 Mavrogianni, 2016; Mulville and Stravoravdis, 2016; Taylor et al., 2016; Hamdy et al., 2017; Pérez-Andreu
31 et al., 2018; Salthammer et al., 2018; Dino and Meral Akgül, 2019; Osman and Sevinc, 2019; Roshan, Oji
32 and Attia, 2019). Decreases in thermal comfort and increases in overheating risks depends on building
33 characteristics, such as thermal resistance, presence of solar shading, thermal mass, ventilation, orientation
34 and geographical location (e.g. Liu and Coley, 2015; van Hooff et al., 2014; Vardoulakis et al., 2015; Dodoo
35 and Gustavsson, 2016; Invidiata and Ghisi, 2016; Makantasi and Mavrogianni, 2016; Mulville and
36 Stravoravdis, 2016; Taylor et al., 2016; Hamdy et al., 2017; Pérez-Andreu et al., 2018; Salthammer et al.,
37 2018; Dino and Meral Akgül, 2019; Osman and Sevinc, 2019; Roshan, Oji and Attia, 2019; Alves,
38 Gonçalves and Duarte, 2021). Most of these studies employed numerical simulations in which different
39 climate scenarios were used to construct future climate data. In hot climates, energy-efficient buildings with
40 high insulation values and high airtightness, which have insufficient protection from solar heat gains and/or
41 limited ventilation capabilities, are generally more vulnerable to overheating than older buildings with lower
42 insulation levels ((e.g. van Hooff et al., 2014; Vardoulakis et al., 2015; Makantasi and Mavrogianni, 2016;
43 Mulville and Stravoravdis, 2016; Salthammer et al., 2018; Fisk, 2015; Hamdy et al., 2017; Fosas et al., 2018;
44 Ozarisoy and Elsharkawy, 2019); see also WGIII 9.7 for building heat mitigation/adaptation links).

45

46 Higher urban temperatures result in lower labour productivity levels and economic outputs (medium
47 confidence) ((Graff Zivin and Neidell, 2014; Yi and Chan, 2017; Houser et al., 2015; Stevens, 2017); see
48 Section 8.2.1). Globally, urban heat stress is projected to reduce labour capacity by 20% in hot months by
49 2050 compared to a current 10% reduction (Dunne, Stouffer and John, 2013). Burke et al. (2015)
50 demonstrate a non-linear relationship between temperature and global economic productivity, with potential
51 global losses of 23% by 2100 due to climate change alone. In specific cases, Zander et al. (2015) estimate
52 heat-related reductions in urban labour productivity in Australia to cost USD 3.6 to USD 5.1 billion per year,
53 based on self-reported performance reduction and absenteeism amongst 1,726 workers in 2013­142; while
54 the high-temperature subsidies given in China at outdoor air temperatures above 35°C are projected to

2 Paper provides figures in Australian dollars: $5.2­7.3 billion Australian dollars. Exchange rate correct July 2020.

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 1 increase to USD 35.7 billion per year after 2030 (compared to 5.5 billion USD per year for 1979­2005)
 2 (Zhao et al., 2016) 3.

 3

 4 Higher urban temperatures place unequal economic stresses on residents and households through higher
 5 utilities demand during warm periods, e.g. electricity in regions where air conditioning is predicted to
 6 become more prevalent, and due to medical costs associated with care for heat illnesses and related health
 7 effects, missed work, and other related impacts (medium confidence) (Jovanovi et al., 2015; Liu et al., 2019;
 8 Schmeltz, Petkova and Gamble, 2016; Soebarto and Bennetts, 2014; Zander and Mathew, 2019; Zander et
 9 al., 2015). Such stresses are projected to increase in many regions associated with continuing global-scale
10 climate change and urbanization (e.g. Véliz et al., 2017; Ang, Wang and Ma, 2017; Bezerra et al., 2021),
11 although some of these effects in cold-climate cities are offset by reduced stresses in winter associated with
12 urban heat island or rising temperatures more generally (see Section 6.2.2.4).

13

14 Thermal inequity can also be seen as a distributive justice risk (Mitchell and Chakraborty, 2018). There are
15 often disproportionate increases of risk for individuals of lower socioeconomic status, especially migrants,
16 from exposure to urban heat. These arise from inadequate housing, less access to air-conditioning, and
17 occupations, such as manual labour and waste-picking, that exacerbate heat exposure (Chu and Michael,
18 2018; Santha et al., 2016). Research from South Africa has shown that housing occupied by poor
19 communities regularly experience indoor temperature fluctuations that are between 4 and 5 °C warmer
20 compared to outdoor temperatures (Naicker et al., 2017); while evidence from the United States indicates
21 that historical housing policies ­ particularly the `redlining' of neighbourhoods based on racially motivated
22 perceptions ­ are associated with areas that are exposed to elevated land surface temperatures (Hoffman,
23 Shandas and Pendleton, 2020).

24

25 Social surveys from temperate and tropical cities highlight the risk of reduced quality of life during heat
26 events, including increased incidence of personal discomfort in indoor and outdoor settings, elevated anxiety,
27 depression, and other indicators of adverse psychological health, and reductions in physical activity, social
28 interactions, work attendance, tourism, and recreation (high confidence) (Chow et al., 2016; Elnabawi,
29 Hamza and Dudek, 2016; Obradovich and Fowler, 2017; Wang et al., 2017; Wong et al., 2017; Lam,
30 Loughnan and Tapper, 2018; Alves, Duarte and Gonçalves, 2016). Extreme heat may also have a cultural
31 impact, for example affecting major sporting events, with negative impacts on the athletic performance
32 (Brocherie, Girard and Millet, 2015; Casa et al., 2015) and the experience and health of spectators
33 (Hosokawa, Grundstein and Casa, 2018; Kosaka et al., 2018; Matzarakis et al., 2018; Vanos et al., 2019).

34

35 6.2.2.2 Urban Flooding

36

37 Flood risks in settlements arise from hydrometeorological events interacting with the urban system, which
38 exposes settlements to river (fluvial) floods, flash floods, pluvial (precipitation-driven) floods, sewer floods,
39 coastal floods, and glacial lake outburst floods (Field et al., 2012). Sea level increase and increases in
40 tropical cyclone storm surge and rainfall intensity will increase the probability of coastal city flooding (high
41 confidence) (WG1 Box TS14). Globally, the increase in frequencies and intensities of extreme precipitation
42 from global warming will likely4 expand the global land area affected by flood hazards (medium confidence)
43 ((Alfieri et al., 2018; Alfieri et al., 2017; Hoegh-Guldberg et al., 2018); Chapter 4.2.4.2). Mishra et al. (2015)
44 noted that out of 241 urban areas, only 17% of cities experienced statistically significant increases in
45 frequencies of extreme precipitation events from 1973-2012. In the future, there is some evidence that
46 changes in high intensity short duration (sub-daily) rainfall in urban areas will increase (limited evidence,
47 medium agreement) (Kendon et al., 2014; Ban, Schmidli and Schär, 2015; Abiodun et al., 2017).

48

3 Paper provides figures in yuan: 250 billion yuan per year after 2030 (compared to 38.6 billion yuan per year for 1979­
2005). Exchange rate correct July 2020.
4 In this Report, the following terms have been used to indicate the assessed likelihood of an outcome or a result:
Virtually certain 99­100% probability, Very likely 90­100%, Likely 66­100%, About as likely as not 33­66%, Unlikely
0­33%, Very unlikely 0­10%, and Exceptionally unlikely 0­1%. Additional terms (Extremely likely: 95­100%, More
likely than not >50­100%, and Extremely unlikely 0­5%) may also be used when appropriate. Assessed likelihood is
typeset in italics, e.g., very likely). This Report also uses the term `likely range' to indicate that the assessed likelihood
of an outcome lies within the 17-83% probability range.

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 1 Flooding associated with sea level rise is addressed in more detail in CCP2, with detailed regional examples
 2 from Africa discussed in chapter 9.3. Coastal flooding associated with sea-level rise is exacerbated due to the
 3 significant number of people living in subsiding areas. As a result of this, the average coastal resident is
 4 experiencing (over the last two decades) rates of relative sea-level rise three to four times higher than typical
 5 estimates due to climate-induced changes (Nicholls et al., 2021). This process can also result in release of
 6 coastal waste into urban areas (Beaven et al., 2020).

 7

 8 Urban flooding risks are also increased by urban expansion, and land use and land cover change, which
 9 enlarges impermeable surface areas through soil sealing, impacting drainage of floodwaters with consequent
10 sewer overflows (high confidence) (Arnbjerg-Nielsen et al., 2013; Ziervogel et al., 2016; Aroua, 2016;
11 Kundzewicz et al., 2014). These risks are also driven by increasing societal complexity, urban developmental
12 policy on flood control, and long-term economic growth (Berndtsson et al., 2019), including in mega-cities
13 (Januriyadi et al., 2018). The increase in flood risk from urban development can be considerable; based on
14 modelling of two RCP (4.5 and 8.5) scenarios, Kaspersen et al. (2017) noted flooding in four European cities
15 could increase by up to 10% for every 1% increase in impervious surface area. Risks are also compounded
16 by the location of settlements, with greater risks within cities located in low elevation coastal zones subject
17 to sea level rise, potential land subsidence, and exposure to tropical cyclones (((Koop and van Leeuwen,
18 2017; Hoegh-Guldberg et al., 2018); see also CCP 2.2) and within informal settlements, where generally
19 little investment in drainage solutions exists and flooding regularly disrupts livelihoods and
20 disproportionately undermines local food safety and security for the urban poor ((Dodman, Colenbrander and
21 Archer, 2017; Dodman et al., 2017; Kundzewicz et al., 2014); Chapter 5.4 and 5.8).

22

23 Future risks of urban flooding is increasing in conjunction with continued increases in global surface
24 temperature (high confidence) (Pörtner et al., 2019; Winsemius et al., 2015; Kulp and Strauss, 2019; Hoegh-
25 Guldberg et al., 2018). In particular, Asian cities are highly exposed to future flood risks arising from
26 urbanization processes. Between 2000 and 2030, rapid urbanization in Indonesia will elevate flood risks by
27 76-120% for river and coastal floods, while sea level rise will further increase the exposure by 19-37% (Muis
28 et al., 2015). In Can Tho, Vietnam, current urban development patterns put new assets and infrastructure at
29 risk due to sea level rise and river flooding in the Mekong Delta (Chinh et al., 2017; Chinh et al., 2016).
30 Flooding in urban areas is exacerbated both by encroachment of urban areas into areas that retain water, and
31 by the lack of infrastructure such as embankments and flood walls, as is the case for large areas of Dhaka
32 East (Haque, Bithell and Richards, 2020). Zhou et al. (2019) have also shown that for the city of Hohhot,
33 China, the increase in impervious surfaces contributes between 2-4 times more to modelled annual flood risk
34 compared to risk induced by climate change.

35

36 Global trends in surface water flooding are increasing, which poses risks to vulnerable urban systems
37 depending on current adaptation measures to manage flooding impacts e.g. stormwater management, green
38 infrastructure, and sustainable urban drainage systems (Molenaar et al., 2015). The economic risks
39 associated with future surface water flooding in towns and cities are considerable. For example in the UK,
40 expected annual damages from surface water flooding may increase by Ł60-200 million for projected 2-4°C
41 warming scenarios; enhanced adaptation actions could manage flooding up to a 2°C scenario but will be
42 insufficient beyond that (Sayers et al., 2015). Analyses conducted in South Korea suggests that future flood
43 levels could exceed current flood protection design standards by as much as 70% by 2100, considerably
44 increasing urban flood risk (Kang et al., 2016). Modelling of urban flood damage to in the Kelani River
45 Basin in Sri Lanka showed increased frequency of flooding by 2030 could increase potential urban property
46 damage by up to 10.2%" (Komolafe Akinola, Herath and Avtar, 2018). Urban flood impacts may also
47 exacerbate health burdens (including disease outbreaks of malaria, typhoid and cholera), which are
48 compounded by damage to medical facilities (e.g. damage to hospitals, and disruption of medicinal supply
49 chains), as observed in urban areas of Ghana (Gough et al., 2019). In addition emerging research shows the
50 cascading consequences of hazard events ­ in this case urban flooding - on other risks to wellbeing in ways
51 that are particularly severe for the urban poor, including mental ill-health, incidents of domestic violence
52 impacting children and women, chronic diseases, and salinity of drinking water ((Matsuyama, Khan and
53 Khalequzzaman, 2020); Chapter 4.2.4.5; Chapter 6.2.4.2; Box 7.2; Chapter 8.4.5.2).

54

55 6.2.2.3 Urban water scarcity and security

56

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 1 Urban water scarcity occurs when gaps exist between supply and demand of available freshwater resources
 2 (Zhang et al., 2019). Urban water security requires a sustainable quantity and quality of water to meet
 3 community and ecosystem needs in a changing climate (Romero-Lankao and Gnatz, 2019; Allan, Kenway
 4 and Head, 2018; Huang, Xu and Yin, 2015; Chen and Shi, 2016). Risks arising from urban water scarcity
 5 worldwide are very likely increasing due to climate drivers (e.g. warmer temperatures and droughts) and
 6 urbanization processes (e.g. land use changes, migration to cities, and changing patterns of water use
 7 including over extraction of surface and groundwater resources) affecting supply and demand (high
 8 confidence) ((Allan, Kenway and Head, 2018; Crausbay et al., 2020; Haddeland et al., 2014; Pickard et al.,
 9 2017; De Stefano et al., 2015; Sun et al., 2019; Van Loon et al., 2016; Zhang et al., 2019); Chapter 4.2.4.4;
10 See Box 8.6 for case study on 2018 Cape Town drought). Flörke et al. (2018) estimates that nearly a third of
11 all major cities worldwide may exhaust their current water resources by 2050. Globally, projections suggest
12 that 350 million (± 158.8 million) more people living in urban areas will be exposed to water scarcity from
13 severe droughts at 1.5°C warming, and 410.7 million (± 213.5) at 2°C warming (Liu et al., 2018).

14

15 Decreased regional precipitation and associated changes in runoff and storage from droughts is exacerbating
16 urban scarcity by impairing the quality of water available for its resource management in cities (high
17 confidence). For example, less runoff to freshwater rivers can increase salinity, concentrate pathogens and
18 pollutants that increases risks of urban water scarcity (Hellwig, Stahl and Lange, 2017; Jones and van Vliet,
19 2018; Leddin and Macrae, 2020; Lorenzo and Kinzig, 2020; Ma et al., 2020; Mosley, 2015; Zhang et al.,
20 2019; van Vliet, Flörke and Wada, 2017) ; See also Box 6.2). Drought also changes the dynamics of
21 groundwater pollution leading to increased environmental health risks when those sources are used for urban
22 water supplies (Kubicz et al., 2021; Moreira et al., 2020; Pincetl et al., 2019). Changes in the nature of
23 droughts e.g. hotter droughts (Herrera and Ault, 2017), snow droughts (Cooper, Nolin and Safeeq, 2016;
24 Mote et al., 2016), or `flash' droughts (Otkin et al., 2016; Otkin et al., 2018; Pendergrass et al., 2020) can
25 exacerbate urban water scarcity exposing the limitations of engineered water infrastructure, designed to
26 accommodate historical patterns of supply and demand (Gober et al., 2016; Ulibarri and Scott, 2019; Zhao et
27 al., 2018a).

28

29 Risks of urban water scarcity and security are compounded by vulnerabilities such as service availability and
30 quality of infrastructure to supply water for increased urban demand from in-migration to cities (medium
31 confidence) (Ahmadalipour et al., 2019; Dong et al., 2020; Reynolds et al., 2019; Thomas et al., 2017;
32 Mullin, 2020). Risks to local water security in cities are also exacerbated by drivers such as dependence on
33 imported water resources from distant locales that may be exposed to additional drought risks (high
34 confidence) (Ahams et al., 2017; Li et al., 2019b; Marston et al., 2015; Zhao et al., 2020; Zhang et al., 2020);
35 from considerable projected urban expansion in drought-stressed areas e.g. across drylands of Western Asia
36 and North Africa (Güneralp et al., (2015b); and by export of virtual water (i.e. export of water embedded in
37 food and energy) from local sources to distant trading partners (Djehdian et al., 2019; D'Odorico et al., 2018;
38 Fulton and Cooley, 2015; Rushforth and Ruddell, 2016; Verdon-Kidd et al., 2017; Vora et al., 2017).

39

40 Droughts interact and manifest in complex ways in interconnected urban areas that likely increase risks of
41 urban water scarcity (Tapia et al., 2017; Rushforth and Ruddell, 2015). Urban interdependencies mean
42 droughts in one region can limit water resources availability in another (e.g., Macao and Zhuhai, Hong
43 Kong, Shenzhen in China, Singapore and Johor, and in cities in Pakistan and India, in the west and southwest
44 USA) (Chuah, Ho and Chow, 2018; Gober et al., 2016; Srinivasan, Konar and Sivapalan, 2017; Zhang et al.,
45 2019; Zhao et al., 2020). Likewise, physical and social teleconnections mean decisions made about water
46 resources in one region or location may impact another in unexpected ways (Moser and Hart, 2015; Liu et
47 al., 2015).

48

49 Urban water security risks are confounded by inequities in economic opportunity, risk exposure, and human
50 well-being (medium evidence)((Sena et al., 2017; Stanke et al., 2013); Chapter 4.2.4.5). Water scarcity is felt
51 more acutely among low-income compared to high-income populations (Nerkar et al., 2016), and scarcity on
52 top of inequities and political instability can lead to security issues e.g. conflict between different water users
53 (Cosic et al., 2019; von Uexkull et al., 2016; Ahmadalipour et al., 2019; Döring, 2020; Ide et al., 2021),
54 particularly when road infrastructures and access to water are limited (Detges, 2016; Sena et al., 2017).
55 Scarcity risks may also be exacerbated by human and ecosystem needs in water short years (Srinivasan,
56 Konar and Sivapalan, 2017). Finally, growing populations along with migration into water scarce regions
57 can exacerbate water security issues (Akhtar and Shah, 2020; Singh and Sharma, 2019).

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 1

 2 6.2.2.4 Other dynamic interactions

 3

 4 A range of other dynamic climate interactions are relevant for cities, settlements, and infrastructure: cold
 5 spells, landslides, wind, fire, and air pollution.

 6

 7 Cold spells. Although frequencies and intensities of cold spells/cold waves are virtually certain to have
 8 decreased globally, and are projected to consistently decrease for most warming levels (high confidence);
 9 WGI Table 11.2), cold weather events can periodically occur and impact urban areas and their connected
10 infrastructures. For cities in eastern Canada, the intra-annual distribution of freezing rain events may become
11 more frequent from December-February, and less frequent in other months by 2100 (Cheng, Li and Auld,
12 2011). Freezing rain is also a risk to urban populations and infrastructure. In general, higher population
13 mortality rates likely occur during the winter season, while more temperature-attributable deaths are caused
14 by cold than by heat in cities located in temperate climates (Gasparrini et al., 2015; Chen et al., 2017; Ryti,
15 Guo and Jaakkola, 2016). Winter mortality is unlikely to significantly decrease due to warming trends, partly
16 because a range of other medical factors (e.g. influenza seasons, and elevations in cardiac risk factors) also
17 drive this winter-excess mortality (Kinney et al., 2015). However, the evidence is unclear whether mortality
18 related to cold waves will decrease in coming decades in European (Smid et al., 2019), or United States
19 cities (Wang et al., 2016). While projected global cold extremes are expected to decrease in frequency and
20 intensity, the higher regional variability of future climates means that cold waves may remain locally
21 important threats, including in milder regions where there are larger temperature differences between
22 `normal' winter days and extreme cold events, and where there is less capacity to adapt (Ma, Chen and Kan,
23 2014; Ho et al., 2019). This will be accentuated in many cities, particularly in Europe, by anticipated
24 demographic changes that result in a more elderly population susceptible to cold wave health risks (Smid et
25 al., 2019).

26

27 The effects of cold waves on the energy sector include breakdowns in power plants and reduced oil and gas
28 production (Jendritzky, 1999), and failures in overhead power lines and towers leading to outages in
29 Moscow and Bucharest (Panteli and Mancarella, 2015; Andrei et al., 2019). Six major power outages
30 associated with cold shocks and ice storms have been recorded since 2010, the majority recorded from large
31 cities the US (Ańel et al., 2017). Cold waves can also significantly increase energy demand. A cold wave
32 that affected the Iberian Peninsula in January 2017 caused electricity prices to peak at a mean price of 112.8
33 /MWh, the highest ever recorded in Spain (AEMET, 2017).

34

35 Landslides. While geomorphological events (e.g. land subsidence from permafrost thaw at high latitudes or
36 from groundwater extraction), and factors associated with the built environment (e.g. settlement location
37 adjacent to steep slopes, and zonation laws for building construction) are major factors determining urban
38 landslide risk, these can also be influenced by a range of climatic variables, namely precipitation (frequency,
39 intensity and duration), snow melt and temperature change. Some 48 million people are exposed to landslide
40 risk in Europe alone, with the majority in smaller urban centres (Mateos et al., 2020). Travassos et al. (2020)
41 also documented all landslide deaths in the Săo Paulo Macro Metropolis Region from 2016-2019 occurred
42 from extreme rainfall events in vulnerable areas prone to landslides. An increase in the number of people
43 exposed to urban landslide risks is projected for landslide-prone settlements lying within regions projected to
44 experience corresponding increase in extreme rainfall (Gariano and Guzzetti, 2016). In addition, human
45 factors such as expansion of towns onto unstable land and land use changes within settlements (e.g., road
46 building, deforestation) are increasing human exposure to landslides, and the likelihood of landslides
47 occurring (Kirschbaum, Stanley and Zhou, 2015). Rainfall triggered landslides kill at least 5000 people per
48 year, and at least 11.7% of these landslides occurred on road networks (Froude and Petley, 2018). Although
49 the spatial footprint of an individual landslide might be small (i.e., <1km2), the `vulnerability shadow' cast
50 over an area in terms of regional transport network disruptions can be a significant proportion of a region,
51 and cascade to other infrastructures (Winter et al., 2016).

52

53 Landslides tend to occur on moderate to steep slopes, and are thus particularly prevalent in mountainous
54 regions which are also characterised by low infrastructure redundancy (i.e., few alternative routes) and
55 increased impacts from climate change (Schlögl et al., 2019). More robust forecasts of landslides driven by
56 climate risk requires (a) more complete long-term records of previous landslides and (b) baseline studies of
57 the Global South which are currently missing from the literature (Gariano et al., 2017).

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 1

 2 Wind. Urban morphology alters wind conditions at multiple spatial scales; generally, increased surface
 3 roughness in settlements have resulted in declining trends in both measured wind speed and frequency of
 4 extremely windy days ((Mishra et al., 2015; Peng et al., 2018; Ahmed and Bharat, 2014); WGI Box 10.3).
 5 Urban wind risks can also be affected by city location adjacent to mountains, lakes, or coasts with localised
 6 wind systems (WGI 10.3.3.4.2; WGI 10.3.3.4.3). In large cities with significant urban heat island, an urban-
 7 driven thermal circulation can enhance pollution dispersion under calm conditions (Fan, Li and Yin, 2018) or
 8 advect heat to areas downwind of the city (Bassett et al., 2016). Microscale wind conditions within urban
 9 canyons also strongly affect ventilation of air pollution dispersion and thermal comfort at pedestrian level,
10 especially in cities located in warm climates (Rajagopalan, Lim and Jamei, 2014; Middel et al., 2014; Lin
11 and Ho, 2016).

12

13 In cities, wind risks from climate change hazards can arise from increased exposure from the expanding built
14 environment. Very high wind speeds associated with severe weather systems e.g. tropical cyclones or
15 derechos can cause significant structural damage to buildings and key infrastructure with insufficient wind
16 load, as well as causing human injury through flying debris (Burgess et al., 2014). In particular, there is
17 evidence from North American cities that tornado damage are likely fundamentally driven by growing built-
18 environment exposure (medium confidence) (Ashley et al., 2014; Rosencrants and Ashley, 2015; Ashley and
19 Strader, 2016).

20

21 Extreme winds in urban areas can have particularly damaging effects on poorly constructed buildings,
22 including low-income houses in African cities (Okunola, 2019), as well as on urban trees that may be
23 uprooted by strong wind gusts from downbursts (Ordóńez and Duinker, 2015; Pita and de Schwarzkopf,
24 2016; Brandt et al., 2016), and on disrupting transportation along urban road and railway networks (Koks et
25 al., 2019; Pregnolato et al., 2016).

26

27 Fire. Hotter and drier climates in several regions e.g. Australia, the Western United States, the
28 Mediterranean, and Russia (Masson-Delmotte and Waterfield, 2018), likely enable weather conditions
29 driving fire events impacting cities within these regions (Chapter 2.4.4.2, 2.5.5.2). These include wildfires
30 along the margins where cities are adjacent to wildlands i.e. the wildland-urban interface (WUI) (Bento-
31 Gonçalves and Vieira, 2020; Radeloff et al., 2018), or fires in cities with a high degree of informal
32 settlements having greater vulnerability to fire hazards ((Kahanji, Walls and Cicione, 2019; Walls and
33 Zweig, 2017); Chapter 8.3.3.2). This vulnerability is considerable; over 95% of urban fire related deaths and
34 injuries occur within informal settlements in in low- and middle-income countries (Rush et al., 2020).

35

36 For wildfires at the WUI, anthropogenic climate change, natural weather variability, expansion of human
37 settlement and a legacy of fire suppression are key factors in determining fire risk (Abatzoglou and
38 Williams, 2016; Knorr, Arneth and Jiang, 2016; van Oldenborgh et al., 2020). Recent wildfires in Australia
39 and in California both occurred under hot and dry weather conditions exacerbated by climate change, and
40 resulted in substantial property damage along the WUI, ecosystem destruction, and lives lost (Brown et al.,
41 2020; Lewis et al., 2020; Yu et al., 2020). Future climate risk of fires at the WUI are likely (medium
42 confidence), and are compounded by projected urban development along WUI within several regions, such
43 as in the Western United States (Syphard et al., 2019), Australia (Dowdy et al., 2019) and the Bolivian
44 Chiquitania (Devisscher et al., 2016).

45

46 Air Pollution. Despite recent observed improvements in air quality arising from COVID-19 restrictions
47 (Krecl et al., 2020); WGI Cross-Chapter Box 6.1), significant risks to human health in cities leading to
48 premature mortality very likely arise from exposure to decreased outdoor air quality from a combination of
49 biogenic (e.g. wildfires at the WUI that advect into the urban atmosphere; (Reddington et al., 2014); WGI
50 Chapter 12 Box 12.1), and anthropogenic sources that are influenced by climate change (e.g. fine particulate
51 matter such as PM2.5, tropospheric ozone, oxides of nitrogen, and volatile organic compounds)((Burnett et
52 al., 2018; Knight et al., 2016; Turner et al., 2016; West et al., 2016; Chang et al., 2019b; Li et al., 2019a;
53 Alexader, Luisa and Molina, 2016); WGI Chapter 6.7.1.1, 6.7.1.2). Risks of premature mortality from indoor
54 air pollution in cities, arising from biomass burning for heating in winter or cooking, indoor pesticide use, or
55 exposure to volatile organic compounds from poor thermal insulation in buildings, are also likely to occur
56 ((Leung, 2015; Peduzzi et al., 2020); Cross-Chapter Box HEALTH in Chapter 7).

57

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 1 The mortality risk for several pollutants, e.g. PM2.5, is considerable (high confidence). Current estimates
 2 indicate that 95% of global population live in areas where ambient PM2.5 exceeds the WHO guideline of
 3 annual average exposure of 10 µg m-3 (Shaddick et al., 2018a; Shaddick et al., 2018b; Chang et al., 2019b).
 4 Among the 250 most populous urban areas, estimated PM2.5 concentrations are generally highest in cities in
 5 Africa, South Asia, the Middle East, and East Asia; PM2.5 in many cities in North Africa and the Middle East
 6 is likely due mainly to windblown dust, whereas that in South Asia and East Asia are mainly anthropogenic
 7 in origin (Anenberg et al., 2019). However, data on PM2.5 concentrations are unavailable in many cities in
 8 low- and middle-income countries due to a lack of measurements (Martin et al., 2019).

 9

10 For some air pollutants e.g. concentrations of PM2.5 in several United States, Western European, and Chinese
11 cities have recently decreased as a result of clean air regulations that have controlled emissions from sources
12 such as motor vehicles, fossil fuel power plants, and major industries (Zheng et al., 2018a; Fleming et al.,
13 2018). These decreases have brought substantial improvements in public health in settlements within these
14 regions (Ciarelli et al., 2019; Zhang et al., 2018). In South Asia, Southeast Asia, and Africa, however,
15 concentrations of other air pollutants e.g. tropospheric ozone, oxides of nitrogen, and volatile organic
16 compounds are likely to continue to grow and peak by mid-century before they subside due global
17 urbanization assumptions embedded in the SSPs (WGI Chapter 6.2.1; 6.7.1). Broadly, future air pollutant
18 emissions are projected to decline globally by 2050 as societies become wealthier and more willing to invest
19 in air pollution controls, but the trajectories vary among pollutants, world regions, and scenarios (Silva et al.,
20 2016b; Rao et al., 2017; Silva et al., 2016c). Whereas cities in East Asia and South Asia currently have large
21 exposure to anthropogenic air pollution, African cities may emerge by 2050 as the most polluted because of
22 growing populations and demand for energy, increased urbanization, and relatively weak regulations to
23 control emissions (Liousse et al., 2014).

24

25 Studies modelling climate change impacts on air quality find that the spatiotemporal patterns of
26 concentration changes vary strongly at urban scales, and that often those patterns differ among the different
27 years modelled due to internal variability (Saari et al., 2019), and different models used (Weaver et al.,
28 2009). Changes in PM2.5 due to climate change are less clear than for ozone, and may be relatively smaller
29 (Westervelt et al., 2019), as climate change can affect PM2.5 species differently (Fiore, Naik and
30 Leibensperger, 2015). For Beijing, climate change is expected to cause a 50% increase in the frequency of
31 meteorological conditions conducive to high PM2.5 concentrations (Cai et al., 2017). The impacts of future
32 climate change on air quality and consequent risks on human health have been studied at urban (Knowlton et
33 al., 2004; Physick, Cope and Lee, 2014) and national scales (Fann et al., 2015; Orru et al., 2013; Doherty,
34 Heal and O'Connor, 2017); globally, these studies have found a likely net increased risk of climate change
35 on air pollution-related health (low confidence). They have focused mainly on the US and Europe with few
36 studies elsewhere (Orru, Ebi and Forsberg, 2017), although the relationship between climate and air quality
37 in megacities is particularly complex (Baklanov, Luisa and Molina, 2016). Silva et al. (2017) found that
38 global premature mortality attributable to climate change (and not from urbanisation) from ozone and PM2.5
39 will increase by about 260,000 deaths per year in 2100 under RCP8.5 , but substantial variance in results
40 exists between individual models.

41

42 6.2.3 Differentiated Human Vulnerability

43

44 Evidence from urban and rural settlements is unambiguous; climate impacts are felt unevenly, with
45 differentiated human vulnerability leading to uneven social, spatial and temporal loss, risk and experiences
46 of resilience - including capacity for transformation (high confidence) (Woroniecki et al., 2019; Tan, Xuchun
47 and Graeme, 2015; Simon and Leck, 2015; Long and Rice, 2019; Chu, Anguelovski and Roberts, 2017;
48 Borie et al., 2019). The evidence is also clear that for those with fewest resources and already constrained
49 life chances, losses from climate change associated events reduce wellbeing and exacerbate vulnerability
50 (high confidence) (van den Berg and Keenan, 2019; Kashem, Wilson and Van Zandt, 2016; Michael,
51 Deshpande and Ziervogel, 2018). Human vulnerability is influenced by the adaptive capacity of physical
52 (built) structures, social processes (economic, wellbeing and health) and institutional structures
53 (organisations, laws, cultural and political systems/norms) (see 6.4). This section should be read in
54 conjunction with Chapter 8 (Poverty, livelihoods and sustainable development) and will emphasise urban
55 processes that lead to the creation of differential vulnerability, risks and impacts.

56

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 1 6.2.3.1 Urban Poverty and Vulnerability

 2

 3 In both developed and less-developed regions, poverty in urban areas is frequently associated with higher
 4 levels of vulnerability (Huq et al., 2020b). This is evident in both rural and urban settlements in a wide range
 5 of contexts, including the Philippines (Porio et al., 2019; Valenzuela, Esteban and Onuki, 2020), Bangladesh
 6 (Matsuyama, Khan and Khalequzzaman, 2020), Brazil (Lemos et al., 2016), Santiago, Chile (Inostroza,
 7 Palme and de la Barrera, 2016) and New York City (Madrigano et al., 2015).

 8

 9 For individuals in urban communities, new literature highlights how differences in vulnerability established
10 by social and economic processes are further differentiated by household and individual variability and
11 intersectionality (Kaijser and Kronsell, 2014; Kuran et al., 2020).This includes differences in wealth and
12 capacity (Romero-Lankao, Gnatz and Sperling, 2016); gender and non-binary gender (Michael and
13 Vakulabharanam, 2016; Sauer and Stieß, 2021; Mersha and van Laerhoven, 2018); education, health,
14 political power and social capital (Lemos et al., 2016); age, including young and elderly, low physical
15 fitness, pre-existing disability, length of residence and social and ethnic marginalization (Inostroza, Palme
16 and de la Barrera, 2016; Schuster et al., 2017; Malakar and Mishra, 2017). An increasing proportion of
17 refugees and displaced people now live in urban centres, and their characteristics also make them vulnerable
18 to a range of shocks and stresses (Earle, 2016). While some individuals, including children may be able to
19 exercise agency to reduce their risk (Treichel, 2020) and some indicators are culturally specific, overall,
20 poor, marginalized, socially isolated and informal urban households are particularly at risk (high confidence)
21 (Brown and McGranahan, 2016; Kim et al., 2020b; Huq et al., 2020a; Huq et al., 2020b).

22

23 6.2.3.2 Informality, planning, and vulnerability

24

25 Particularly in Low- and Middle-Income Countries, much urban building occurs outside formal parameters
26 and entails a high degree of urban informality. According to the United Nations statistics, the proportion of
27 urban populations living in slums and informal settlements increased from 23% in 2014 to 23.5% in 2018
28 (United Nations, 2018). Informality is one pathway through which urbanization generates differentiated
29 vulnerability tending to increase exposure and susceptibility of physical structures and their occupants to
30 climate-related risks (Dodman et al., 2017; Dobson, 2017) in contexts including Guadalajara, Mexico (Gran
31 Castro and Ramos De Robles, 2019), Kampala, Uganda (Richmond, Myers and Namuli, 2018), Bengaluru,
32 India (Kumar, Geneletti and Nagendra, 2016), and Dar es Salaam, Tanzania (Yahia et al., 2018). In addition
33 to facing emerging water- and heat-related risks, such areas are also more vulnerable to the health impacts of
34 climate change (Scovronick, Lloyd and Kovats, 2015).

35

36 Even where formal planning is the norm, this has often remained oriented toward enabling value adding
37 construction or the protection of existing high value physical assets, e.g., infrastructure and built cultural
38 heritage; private residential) rather than enabling disaster risk reduction for all (Long and Rice, 2019). This
39 tendency has been widely documented, including from cases in Australia, Thailand and Indonesia (King et
40 al., 2016), Canada (Stevens and Senbel, 2017), Amman, Moscow, and Delhi (Jabareen, 2015), and South
41 Africa (Arfvidsson et al., 2017). Such inconsistencies between the delivery of land-use planning and the aims
42 of the Sustainable Development Goals combine with other social structures, economic pathways, and
43 governance systems to shape city risk profiles (Dodman et al., 2017).

44

45 6.2.3.3 Migration and differentiated vulnerability

46

47 Migration, displacement, and resettlement each play a foundational role in differentiated vulnerability (see
48 Cross-Chapter Box MIGRATE in Chapter 7). The relationship between migration and vulnerability is
49 complex (robust evidence, high agreement), and is the first of the three components discussed within this
50 section. Climate change, as a push factor, is only one among multiple drivers (political, economic, and
51 social) related to environmental migration (Heslin et al., 2019; Plänitz, 2019; Luetz and Merson, 2019).
52 There is consensus that it is difficult to pin climate change as the sole driver of internal (within national
53 boundaries) rural to urban migration decisions due to, among other factors, the disconnect between national
54 and international policies (Wilkinson et al., 2016), the lack of unifying theoretical frameworks, and the
55 complex interactions between climatic and other drivers (social, demographic, economic, and political) at
56 multiple scales (Cattaneo et al., 2019; Borderon et al., 2019). Environmental migration ­ including rural to
57 urban migration ­ triggered by climate change may ensue from either slow or rapid onset climatic events and

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 1 could be either temporary, cyclical, or permanent movement that occurs within or beyond national
 2 boundaries (Heslin et al., 2019; Silja, 2017).

 3

 4 A range of specific studies highlight specific elements of vulnerability and migration, including the ways in
 5 which slow-onset events affect precarious, resource dependent livelihoods (such as farming and fisheries)
 6 (Cai et al., 2016). In small town Pakistan and in small town Colombia, heat stress increases long-term
 7 migration of men, driven by a negative effect on farm income (Mueller, Gray and Kosec, 2014; Tovar-
 8 Restrepo and Irazábal, 2013). A study from Mexico reveals that an increase in drought months led to
 9 increased rural to urban migration, while increased heat (temperature) led to a "non-linear" pattern of rural to
10 urban migration that occurred only after extended periods of heat (nearly 34 months) (Nawrotzki et al.,
11 2017). This aligns with other findings that a consistent increase in temperature between 2-4oC in some parts
12 of the world render involuntary, forced migration inevitable (Otto et al., 2017).

13

14 The complexity of migration drivers (as push or as pull factors) explains why there is little agreement around
15 quantitative estimates on migration (especially international) triggered by climate change (Silja, 2017; Otto
16 et al., 2017), and why estimates of future displacement attributed to climate change and other environmental
17 causes vary between 25 million and 1 billion in 2050 (Heslin et al., 2019). Many authors are critical of
18 existing perspectives on climate-related migration, and argue for more nuanced research on the topic (Boas
19 et al., 2019; Kaczan and Orgill-Meyer, 2020; Silja, 2017; Sakdapolrak et al., 2016; Singh and Basu, 2020;
20 Luetz and Havea, 2018).

21

22 Climate-induced migration is not necessarily higher among poorer households whose mobility is more likely
23 to be limited due to the poverty trap (i.e., lack of financial resources) (high confidence) (Cattaneo et al.,
24 2019; Kaczan and Orgill-Meyer, 2020; Silja, 2017). For example, in Bangladesh, vulnerability of rural
25 populations is increasing, so many of the poorest employ migration as a strategy of last resort (Paprocki,
26 2018; Penning-Rowsell, Sultana and Thompson, 2013; Adri and Simon, 2018) that occurs as soil salinity (as
27 opposed to inundation alone) increases and is paralleled by economic diversification (i.e., aquaculture) (Chen
28 and Mueller, 2018). There is robust evidence and high agreement that rapid-onset climatic events trigger
29 involuntary migration and short-term, short-distance mobilities (Cattaneo et al., 2019). There is also robust
30 evidence and high agreement that slow-onset climatic events (such as droughts and sea-level rise) lead to
31 long-distance internal displacement more so than local or international migration (Kaczan and Orgill-Meyer,
32 2020; Silja, 2017); while sea level rise is expected to lead to the displacement of communities along coastal
33 zones, such as in Florida in the USA (Hauer, 2017; Butler, Deyle and Mutnansky, 2016).

34

35 Migration, including rural-urban migration, is also recognized as an adaptation strategy in some
36 circumstances, whether this is voluntary or planned (Jamero et al., 2019; Esteban et al., 2020a; Bettini,
37 2014). Voluntary migration can be an element of household strategies to diversify risk, depending on the
38 nature of the climatic stress and interacts with household composition, individual characteristics, social
39 networks, and historical, political, and economic contexts (Hunter, Luna and Norton, 2015; Carmin et al.,
40 2015; Hayward et al., 2020). For example, in Colombia, rural to urban migration is differentiated across
41 gender depending on the climatic stress whereby men migrate due to droughts, while women migrate due to
42 excessive rain triggers (Tovar-Restrepo and Irazábal, 2013). Especially in Pacific small island developing
43 states, migration can be a strategy for urban settlements or tribal communities to relocate in customary areas,
44 as in the case of Vunidogoloa in Fiji (McMichael, Katonivualiku and Powell, 2019; Hayward et al., 2020); it
45 can be a livelihood strategy as shown in the Cataret Islands in Papua New Guinea (Connell, 2016); or it can
46 be used to enhance education and international networks (i.e., voluntary "migration with dignity") as is the
47 case in Kiribati (Heslin et al., 2019; Voigt-Graf and Kagan, 2017).

48

49 The second component, displacement, also plays a crucial role in differentiated vulnerability. The lack of
50 resources and capacities to support mobility limits the effectiveness of migration as an adaptation strategy,
51 therefore leading to both displacement and trapped populations in the future (Adger et al., 2015; Faist, 2018).
52 For example, studies from Colombia (Tovar-Restrepo and Irazábal, 2013), India (Singh and Basu, 2020),
53 Mekong Delta in Vietnam (Miller, 2019), and Pakistan (Islam and Khan, 2018) showed that migration as an
54 adaptation strategy can be constrained due to resource barriers and low mobility potential, and also, to high-
55 levels of place attachment such as, in the Peruvian Highlands (Adams, 2016), Vanuatu (Perumal, 2018), and
56 the Tulun and Nissan Atolls of Bougainville, Papua New Guinea (Luetz and Havea, 2018). Migration can
57 also be maladaptive for the receiving contexts whether due to the pressure on and/or conflict over land

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1 and/or the urban resources (high confidence) (Faist, 2018; Singh and Basu, 2020; Luetz and Havea, 2018).
2 Other views maintain that migration as adaptation overlooks the agency of people and their resilience ­i.e.,
3 the nuances of `translocal social resilience' (Kelman, 2018; Silja, 2017; Sakdapolrak et al., 2016). For

4 example, the ni-Vanuatu prioritize in-situ adaptation measures and leave migration as a last resort (Perumal,

5 2018).

6

7 Regardless of the reasons and the initiators for migration, community control over resettlement both at the

8 original and destination leads to more positive outcomes for both the communities being resettled and the

 9 receiving communities (high confidence) (Perumal, 2018; Ferris, 2015; Price, 2019; Mortreux and Adams,
10 2015; Tadgell, Doberstein and Mortsch, 2018; Luetz and Havea, 2018). The protection of livelihoods
11 contributes to ensuring the wellbeing (physical and mental) and the protection of the rights of communities
12 (high confidence) (Ferris, 2015; Price, 2019). There is limited evidence but high agreement that the outcomes
13 of resettlement initiatives are complex and multi-faceted (Ferris, 2015). For example, in Shangnan County,
14 northwest China, the Massive Southern Shaanxi Migration Program, based on voluntary participation,
15 reduced risk exposure and improved the quality of life in general, but also disproportionately increased the
16 vulnerability of disadvantaged groups (the poor, migrants, and those left behind) (Lei et al., 2017). Similarly,
17 vulnerability increased due to the loss of connection to place and community bonds in Mekong Delta,

18 Vietnam (Miller, 2019) and due to unsafe construction, poor infrastructure, institutional incapacity, and
19 general neglect in resettlement initiatives in Malawi, sub-Saharan Africa (Kita, 2017).

20

21 6.2.4 Risks to Key Infrastructures

22

23 Projected climatic changes ­ such as changing precipitation patterns, temperatures, and sea levels ­
24 contribute to pressures on human wellbeing and the functioning of infrastructure systems (high confidence).

25 Furthermore, risks evolve due to macro-scale drivers of change such as urbanization, economic development,

26 land use changes and other emergent factors (Adger, Brown and Surminski, 2018). Infrastructure networks
27 are rapidly growing around the world (see Table 6.3). Since the quality and accessibility of infrastructure
28 services are varied, it is important to understand how climate change poses different kinds of risk on them.
29 Infrastructure can be broadly understood to include social infrastructure (housing, health, education,
30 livelihoods and social safety nets, security, cultural heritage/institutions, disaster risk management and urban
31 planning), ecological infrastructure (clean air, flood protection, urban agriculture, temperature, green
32 corridors, watercourses and riverways) and physical infrastructure (energy, transport, communications
33 (including digital), built form, water and sanitation and solid waste management) (Thacker et al., 2019). This

34 section focuses especially on physical infrastructure where the literature provides discrete risk and impact
35 assessments. Physical infrastructure systems are often immobile, indivisible, involve high fixed costs, and
36 have longer lifecycles. Social and ecological infrastructure elements are rarely assessed alone and instead
37 tend to be included in wider assessments of event impacts.

38

39

40 Table 6.3 Selected indicators of global proliferation of infrastructure networks and their annual usage.

    Infrastructure  Scale              Usage on annual Coverage / Equity of access References

                                       basis

    Electricity     >20M km power 25,721 TWh (2017) Global: 3130kWh/person           (IEA, 2019)
    networks                                                                         (World Bank,
                    lines in Europe                       Haiti: 39kWh/person        2019)
                                                                                     (ETSAP, 2014)
                    and USA.                              Iceland: 53,832kWh/person

    Gas and LPG     Worldwide:         40,531 TWh (2017)  Global 4.96 MWh/person     (CIA, 2015)
    pipelines       >2.5M km w                            (2015)                     (OWID, 2020)
                                                          South Africa 0.96
                                                          MWh/person (2015)
                                                          Saudi Arabia: 34.65
                                                          MWh/person (2015)

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    Railways         2.69M km           3,835 billion         Switzerland: 0.7m/person;     (Koks et al., 2019)
                                        passenger km          141m/km2                      (Statista, 2020)
                                        (2019)
                                        9,279.81 billion      Canada: 2.2m/person;
                                        tonne km (2019)       8.6m/km2

                                                              India: 0.06m/person;
                                                              23m/km2

    Roads            63.46M km          12,148 billion        Belgium: 15m/person;          (Koks et al., 2019)
                                        passenger km          5km/km2                       (WorldByMap,
    Information and  Worldwide:         private vehicles      Malawi: 1m/person;            2017)
    Communication    91M mobile         (2015)                164m/km2                      (ITF, 2019)
    Technology       phones in 1995;    5,713 billion         Canada: 31m/person;
    Water            8.2BN in 2018      passenger km          115m/km2                      (ITU, 2019)
                     worldwide          public vehicles e.g.                                (Vodafone, 2019)
                     3.3M km2 land      buses (2015)          Europe: 85% population are    (GSMA, 2019)
                     equipped for       302.5 billion         unique mobile subscribers
                     irrigation         passenger km active   Asia Pacific: 66%             (Grigg, 2019)
                     The Global         modes e.g. walking    SSA: 45%                      (Lehner et al.,
                     Reservoir and      and bicycles (2015)                                 2011)
                     Dam Database       Worldwide:            Sub-Saharan Africa: 24%       (Lehner et al.,
                     (conservatively    43,000 PB in 2014     coverage of safely managed    2019)
                     records) at least  242,000 PB in 2018    drinking water services, 28%  (UN Water, 2018)
                     7100 dams          (*1PB = 1 million     safely managed sanitation
                                        GB)                   services
                                        This irrigated land   Europe & North America:
                                        accounts for about    94%, 78%
                                        70% of total water
                                        withdrawals

                                        These dams can
                                        retain over
                                        7,800km3 water.

1

2

3 Current climate variability is already causing impacts on infrastructure systems around the world (high
4 confidence). For global physical infrastructure with a present value of US$143 trillion The Economist
5 Intelligence Unit (2015) estimates present value losses of $4.2 trillion by 2100 under a 2oC scenario. This
6 estimation rises to $13.8 trillion under a 6oC scenario. Extreme events are associated with disruption or
7 complete loss of these infrastructure services, whilst gradual changes in mean conditions are altering
8 physical infrastructure performance. Physical infrastructure is usually costly to repair and also have
9 significant impacts on people's health and wellbeing.

10

11 This section synthesises and assesses the emerging literature on climate change risks to key physical
12 infrastructure domains as listed in Table 6.3: energy/electricity infrastructure, transportation infrastructure,
13 and information and communication technology (ICT) (water infrastructure is discussed in Section 6.2.2). It
14 draws on evidence from around the world, but the specific risks to infrastructure in different contexts are
15 explained in more detail in the regional chapters (especially 9.8.4.1 for Africa, 10.4.6.3.8 for Asia, and
16 13.6.1 for Europe). For cities and settlements such risks are of particular concern due to a lack of adaptive
17 capacity across many economically important sectors and low levels of resource and capacity support to
18 enhance adaptive capacity. Recent literature also illustrates the interconnected and interdependent nature of
19 infrastructure systems (see Box 6.2), which lead to uncertainties over how risks in one sector lead to
20 cascading, compounding, or knock-on effects across other sectors (Zscheischler and Seneviratne, 2017) (see
21 Section 6.2.6 for elaboration). Therefore, adaptation options should address climate risks to infrastructure in
22 an integrated and co-beneficial manner (medium evidence, high confidence) (see Section 6.3 and Section
23 6.4).

24

25

26 [START BOX 6.2 HERE]

27

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1 Box 6.2: Infrastructure Interdependencies

2

3 Infrastructure networks are increasingly dependent on each other --for power, control (via ICT) and access

4 for deliveries or servicing (see Figure 6.2). Moreover, a range of other mechanisms can create

5 interdependencies that impact upon climate risks by creating pathways for cascading failure (Undorf et al.,
6 2020; Barabási, 2013). In the UK, for example, all infrastructures utilities identify failure of components in
7 another utility as a risk to their systems (Dawson et al., 2018).

8

9 Key interdependencies include:

10

11  i. The use of ICT for data transfer, remote control of other systems, and clock synchronization. Pant et

12  al. (2016) show that ICT is crucial for the successful operation of the UK's rail infrastructure. The

13  study shows that flooding of the ICT assets in the 1-in-200-year floodplain would disrupt 46% of

14  passenger journeys across the whole network.

15 ii. Water to generate hydroelectricity and for cooling thermal power stations. Reductions in usable

16  capacity for 61­74% of the hydropower plants and 81­86% of the thermoelectric power plants

17  worldwide for 2040­2069 (Van Vliet et al., 2016), with some power generation technologies,

18  including carbon capture and storage, requiring far higher volumes of water for cooling (Byers et al.,

19  2016);

20 iii. Energy to power other infrastructure systems. Failure of urban energy supply disrupts other

21  infrastructure services, with disproportionate impacts on the urban poor (Silver, 2015);

22 iv. Transport systems that ensure access for resources such as fuel, personnel and emergency response.

23  Pregnolato et al. (2017) show disruption across the city from a 1-in-10 year storm event could

24  increase by 43% by the 2080s.

25 v. Green infrastructure can provide multiple services, creating interdependencies between multiple

26  physical infrastructure systems. For example, green space can support sustainable urban drainage,

27  in-situ wastewater treatment, and urban cooling (Demuzere et al., 2014).

28 vi. Geographical proximity of assets leads to multiple infrastructures being simultaneously exposed to

29  the same climate hazard. Disruption is disproportionately larger for interconnected networks (Fu et

30  al., 2014).

31

32 There is usually limited information on the risks between infrastructure sectors. Without frameworks for
33 collaboration and coupled with commercial and security sensitivities this remains a barrier to routine sharing

34 and cooperation between operators. Despite this, methods to tackle interdependence in climate risk analysis
35 are emerging (Dawson, 2015). For example, Thacker et al. (2017) analysed the criticality of the UK's
36 infrastructure networks by integrating data on infrastructure location, connectivity, interdependence, and
37 usage. The analysis showed that criticality hotspots are typically located around the periphery of urban areas

38 where there are large facilities upon which many users depend or where several critical infrastructures are

39 concentrated in one location. As infrastructure systems become increasingly interconnected, associated risks
40 from climate change will increase and require a cross-sectoral approach to adaptation (Dawson et al., 2018).

41

42 [END BOX 6.2 HERE]

43

44

45 6.2.4.1 Energy infrastructure

46

47 Energy infrastructure underpins modern economies and quality of life. Disruption to power or fuel supplies
48 impacts upon all other infrastructure sectors, and affects businesses, industry, healthcare, and other critical
49 services both within an across jurisdictional boundaries (Groundstroem and Juhola, 2019). The economic
50 impacts of climate change risks are significant, for example in the EU the expected annual damages to

51 energy infrastructure, currently 0.5 billion per year, are projected to increase 1612% by the 2080s (Forzieri
52 et al., 2018). In China, 33.9% of the population are vulnerable to electricity supply disruptions from a flood
53 or drought (Hu et al., 2016), whilst in the USA, higher temperatures are projected to increase power system
54 costs by about $50 billion by the year 2050 (Jaglom et al., 2014). In a study of 11 Central and Eastern

55 Europe countries, researchers found that energy poverty is exacerbated by existing infrastructure deficits, an

56 energy efficient building stock, as well as income inequality, which can lead to reduced economic
57 productivity (Karpinska and miech, 2020). Climate change is expected to alter energy demand (Viguié et

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 1 al., 2021), for example heatwaves increase spot market prices (Pechan and Eisenack, 2014) with a
 2 disproportionate impact on the poorest and most vulnerable populations. Energy infrastructure are
 3 susceptible to a range of climate risks (Cronin, Anandarajah and Dessens, 2018), whilst issues pertaining to
 4 energy demand are considered by Working Group III.

 5

 6 Climate change can, for example, influence energy consumption patterns by changing how household and
 7 industrial consumers respond to short-term weather shocks as well as how they adapt to long-term changes
 8 (Auffhammer and Mansur, 2014). Recent studies from Stockholm, Sweden, show that future heating demand
 9 will decrease while cooling demand will increase (Nik and Sasic Kalagasidis, 2013). A study from the USA
10 showed that climate change will impacts buildings by affecting peak and annual building energy
11 consumption (Fri and Savitz, 2014). From an infrastructure standpoint, the vulnerability of current
12 hydropower and thermo-electric power generation systems may change due to changes in climate and water
13 systems and projected reduction of usable capacities (Van Vliet et al., 2016; Byers et al., 2016). These
14 examples show how energy infrastructure planning under climate change must take into account a greater
15 number of scenarios and investigate impacts on particular energy segments (Sharifi and Yamagata, 2016).

16

17 Electricity generation. Electricity generation infrastructure can be directly damaged by floods, storm and
18 other severe weather events. Furthermore, the performance of renewables (solar, hydro-electric, wind) is
19 affected by changes in climate.

20

21 Most thermoelectric plants require water for cooling, many are therefore situated near rivers and coasts and
22 therefore vulnerable to flooding. Increases in water temperature or restrictions on cooling water availability
23 affect hydro-electric and thermoelectric plants. A 1°C increase in the temperature of water used as coolant
24 yields a decrease of 0.12-0.7% in power output (Mima and Criqui, 2015; Ibrahim, Ibrahim and Attia, 2014).
25 Excess biological growth, accelerated by warmer water, increases risk of clogging water intakes (Cruz and
26 Krausmann, 2013). While some regions are expected to experience increased capacity under climate change
27 (namely India and Russia), global annual thermal power plant capacity is likely to be reduced by between
28 7% in a mid-century RCP2.6 scenario and 12% in a mid-century RCP8.5 scenario (Van Vliet et al., 2016).
29 Worldwide, hydro-electric capacity reductions are projected 0.4-6.1% (Van Vliet et al., 2016). Analysis of
30 the UK's water for energy generation abstractions showed that an energy mix of high nuclear or carbon
31 capture technologies could require as much as six times the current cooling water demands (Byers, Hall and
32 Amezaga, 2014; Byers et al., 2016).

33

34 Increasing temperatures improve the efficiency of solar heating, but decrease the efficiency of photovoltaic
35 panels, and deposition and abrasive effects of wind-blown sand and dust on solar energy plants can further
36 reduce power output, and the need for cleaning (Patt, Pfenninger and Lilliestam, 2013). Projected changes in
37 wind and solar potential are uncertain, the trends vary by region and season (Burnett, Barbour and Harrison,
38 2014; Cradden et al., 2015; Fant, Schlosser and Strzepek, 2016). In an RCP8.5 scenario, Wild et al. (2015)
39 conservatively calculate a global reduction of 1% per decade between 2005-2049 for future solar power
40 production changes due to changing solar resources as a result of global warming and decreasing all-sky
41 radiation over the coming decades. However, positive trends are projected in large parts of Europe, South-
42 East of North America and the South-East of China.

43

44 Electricity transmission and distribution. Electricity transmission and distribution networks span large
45 distances, with overhead power lines often traversing exposed areas. Power lines and other assets, such as
46 substations, are often located near population centres, including those in floodplains. Structural damage to
47 overhead distribution lines will increase in areas projected to see more ice or freezing rain (e.g. most of
48 Canada), snowfall (e.g. Japan) or wildfires (e.g. California, USA) (Bompard et al., 2013; Mitchell, 2013;
49 Sathaye et al., 2013; Jeong et al., 2018; Ohba and Sugimoto, 2020). Electricity outages maybe last for
50 prolonged periods of time and across vast areas, in addition to potentially disproportionately affecting poorer
51 or more vulnerable communities. Increases in windstorm frequency and intensity increase the risk of direct
52 damage to overhead lines and pylons, in many locations this is limited but Tyusov et al. (2017) calculate an
53 increase as high as 30% in parts of Russia. Where the mode of failure is recorded, transmission pylons are
54 seen to be more susceptible to wind damage, whilst distribution pylons are more likely to be affected by
55 treefall and debris (Karagiannis et al., 2019). Increased temperatures can lead to the de-rating (lower
56 performance) of power lines whose resistance increases with temperature with efficiency reductions of 2-
57 14% being projected by 2100 (Cradden and Harrison, 2013; Bartos et al., 2016).

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 1

 2 Fuels extraction and distribution. Non-electric energy infrastructure is susceptible to many of the same
 3 impacts as the electric infrastructure. Extreme weather events impact extraction (onshore and offshore) and
 4 refining operations of petroleum, oil, coal, gas and biofuels. Disruption of road, rail and shipping routes (see
 5 Section 6.2.5.2) interrupts fuel supply chains. However, there are a number of risks that are specific to these
 6 sectors. Heat can lead to expansion in oil and gas pipes, increasing the risk of rupture (Sieber, 2013). Whilst
 7 heatwaves and droughts can reduce the availability of biofuel (Moiseyev et al., 2011; Schaeffer et al., 2012).
 8 Subsidence and shrinkage of soils damages underground assets such as pipes intakes (Cruz and Krausmann,
 9 2013), while additional human activity such as extractive drilling may induce earthquakes, as observed in the
10 northern Dutch province of Groningen (Van der Voort and Vanclay, 2015). In Alaska, USA, the thaw of
11 permafrost and subsequent ground instability is estimated to lead to $33M damages to fuel pipelines in an
12 end-of-century RCP8.5 scenario (Melvin et al., 2017), with low lying coastal deltas particularly vulnerable
13 (Schmidt, 2015).

14

15 6.2.4.2 Transport

16

17 Since AR5, research has highlighted the implications for disruption to global supply chains (Becker et al.,
18 2018; Shughrue and Seto, 2018; Pató, 2015), and has made advancements in quantifying costs of climate
19 risks to transportation infrastructure. Climate risks to transport infrastructure (from heat- and cold waves,
20 droughts, wildfires, river and coastal floods and windstorms) in Europe could rise from 0.5 billion to over
21 10 billion by 2080s (Forzieri et al., 2018). Across the Arctic, nearly four million people and 70% of all
22 current infrastructure, including resource extraction and transportation routes, will be at risk by 2050 (Hjort
23 et al., 2018), although the design of specific infrastructure may also affect the degree of infrastructure
24 damage depending local geological and ecological conditions. Globally, Koks et al. (2019) calculated that
25 approximately 7.5% of road and railway assets are exposed to a 1/100 year flood event, and total global
26 expected annual damages (EAD) of US$3.1-22 billion (mean $14.6 billion) due to direct damage from
27 cyclone winds, surface and river flooding, and coastal flooding. The majority of this is caused by surface
28 water and fluvial flooding (mean $10.7 billion). Although twice as much infrastructure is exposed to cyclone
29 winds compared to flooding, a mean EAD of $0.5 billion is significantly less that for coastal flooding ($2.3
30 billion) as cyclone damages are largely limited to bridge damage and the cost of removing trees fallen on
31 road carriageways and railway tracks. This is small relative to global GDP (~0.02%). However, in some
32 countries EAD equates to 0.5-1% of GDP, which is the same order of magnitude as typical national transport
33 infrastructure budgets, but especially significant for countries like Fiji that already spend 30% of their
34 government budget on transport (World Bank Group, 2017). Koks et al. (2019) did not assess future climate
35 change impacts, but comparable studies calculating changes in EAD from flooding based upon land use
36 show increases of 170%--1370% depending on global greenhouse gas emissions levels (Alfieri et al., 2017;
37 Winsemius et al., 2015). Moreover, Schweikert et al., (2014) report that climate risks to transport
38 infrastructure could cost as much as 5% of annual road infrastructure budgets by 2100, with disproportionate
39 impacts in some low and lower middle-income countries.

40

41 Changes in rainfall and temperature patterns are expected to increase geotechnical failures of embankments
42 and earthworks (Briggs, Loveridge and Glendinning, 2017; Tang et al., 2018; Powrie and Smethurst, 2018)
43 from landslides, subsidence, sinkholes, desiccation and freeze-thaw action. For instance, Pk et al. (2018)
44 show this could lead to a 30% reduction in the engineering factor of safety of earth embankments in
45 Southern Ontario (Canada). Increased river flows in many catchments will also increase failures from bridge
46 scours (Forzieri et al., 2018). HR Wallingford (2014) calculate that the projected 8% increase in scouring
47 from high river flows in the UK will lead to 1 in 20 bridges being at high risk of failure by the 2080s, whilst
48 in the USA the 129,000 bridges currently deficient could increase by 100,000 (Wright et al., 2012). With
49 respect to temperature, analysis by Forzieri et al. (2018) concludes that heatwaves will be the most
50 significant risk to EU transport infrastructure in the 2080s as a result of buckling of roads and railways due
51 to thermal expansion, melting of road asphalt and softening of pavement material. In the USA, over 50%
52 more roads will require rehabilitation (Mallick et al., 2018), whilst $596m will be required through 2050 to
53 maintain and repair roads in Malawi, Mozambique, and Zambia (Chinowsky, Price and Neumann, 2013).

54

55 In addition to direct damages from flooding and heatwaves, disruption caused by road blockages will be
56 increased by more frequent flood events. For example in the city of Newcastle upon Tyne (UK), road travel
57 disruption across the city from a 1-in-50 year surface water flood event could increase by 66% by the 2080s

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 1 (Pregnolato et al., 2017) whilst heatwaves could treble railway speed restrictions in parts of the UK (Palin et
 2 al., 2013). Knott et al. (2017) highlighted risks to coastal infrastructure where ~30cm sea level rise sea level
 3 rise would also push up groundwater and reduce design life by 5-17% in New Hampshire (USA). Heavy
 4 rain and flooding can also inundate underground transport systems (Forero-Ortiz, Martínez-Gomariz and
 5 Canas Porcuna, 2020).

 6

 7 Many airports, and by their nature ports, are in the low elevation coastal zone making them especially
 8 vulnerable to flooding and sea level rise. Under a 2oC scenario the number of airports at risk of storm surge
 9 flooding increases from 269 to 338 or as many as 572 in an RCP8.5 scenario; these airports are
10 disproportionately busy and account for up to 20% of the world's passenger routes (Yesudian and Dawson,
11 2021). Airport and port operations could be disrupted by icing of aircraft wings, vessels, decks, riggings, and
12 docks (Doll, Klug and Enei, 2014; Chhetri et al., 2015). Warming will increase microbiological corrosion of
13 steel marine structures (Chaves et al., 2016). Fog, high winds and waves can disrupt port and airport activity
14 but changes are uncertain and with regional variation (Mosvold Larsen, 2015; Izaguirre et al., 2021; Becker,
15 2020; León-Mateos et al., 2021; Taszarek, Kendzierski and Pilguj, 2020; Danielson, Zhang and Perrie, 2020;
16 Kawai et al., 2016).

17

18 Waterways are still important transport routes for goods in many parts of the world, although they are mostly
19 expected to benefit from reduced closure from ice (Jonkeren et al., 2014; Schweighofer, 2014), low flows
20 will likely lead to reduced navigability and increased closures, van Slobbe et al. (2016) estimate the Rhine
21 may reach a turning point for waterway transportation between 2070-2095. Obstruction due to debris and
22 fallen vegetation of roads and rails and to inland and marine shipping from high winds are expected to
23 increase (Koks et al., 2019; Kawai et al., 2018; Karagiannis et al., 2019)..

24

25 6.2.4.3 Information and Communication Technology

26

27 Information and Communication Technology (ICT) comprises the integrated networks, systems and
28 components enabling the transmission, receipt, capture, storage and manipulation of information by users on
29 and across electronic devices (Fu, Horrocks and Winne, 2016). ICT infrastructure faces a number of climate
30 risks. Increased frequency of coastal, fluvial or pluvial flooding will damage key ICT assets such as cables,
31 masts, pylons, data centres, telephone exchanges, base stations or switching centres (Fu, Horrocks and
32 Winne, 2016). This leads to loss of voice communications, inability to process financial transactions and
33 interruption to control and clock synchronization signals. Insufficient information about the location and
34 nature of many ICT assets limits detailed quantitative assessment of climate change risks.

35

36 Fixed line ICT networks that sprawl over large areas are especially susceptible to increases in the frequency
37 or intensity of storms would increase the risk of wind, ice and snow damage to overhead cables and damage
38 from wind-blown debris. More intense or longer droughts and heatwaves can cause ground shrinkage and
39 damage underground ICT infrastructure (Fu, Horrocks and Winne, 2016). In mountain and northern
40 permafrost regions, communications and other infrastructure networks are subject to subsidence because of
41 warming of ice-rich permafrost (Shiklomanov et al., 2017; Li et al., 2016; Melvin et al., 2017).

42

43 6.2.4.4 Housing

44

45 For the urban housing sector, climate impacts such as flooding, heat, fire, and wind assessed in Section 6.2.3
46 will likely have detrimental effects on housing stock (including physical damage and loss of property value)
47 as well as on residents exposed to climate risks (robust evidence, high agreement)

48

49 In the USA, for example, 15.4 million housing units fall within a 1-in-100-year floodplain (Wing et al.,
50 2018). Assessment of the Miami-Dade area in Florida noted that coastal inundation caused by tidal flooding
51 (and to a lesser extent sea level rise) resulted in over $465 million in lost real-estate market value between
52 2005 and 2016 (McAlpine and Porter, 2018), although property values have increased from high-end
53 housing construction and climate adaptation measures (Kim, 2020). Emergent risk reflecting novel research
54 include aggravated moisture problems in buildings from wind driven rain (Nik et al., 2015). Future risks
55 from future sea level rise are elaborated in CCP2.2.1. Housing infrastructure are also susceptible to extreme
56 heat and wind events (Stewart et al., 2018). These risks are further elaborated on in Section 6.2.3, although it
57 is important to note that heat risks, in particular, tend to be concentrated within communities with higher

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 1 proportion of social housing (Mavrogianni et al., 2015; Sameni et al., 2015) or low-cost government-built
 2 houses and informal settlements.

 3

 4 6.2.4.5 Water and Sanitation

 5

 6 Apart from land subsidence from urbanization (e.g. Case Study 6.2), substantial climate risks to urban
 7 sanitation arise from droughts, flooding and storm surges. Low flows from drought can lead to
 8 sedimentation, increase pollutant concentration and block sewer infrastructure networks (Campos and Darch,
 9 2015). Flooding poses a greater risk for urban sanitation in low and middle income settings (Burgin et al.,
10 2019) where onsite systems are more common. Floodwater may wash out pits and tanks, mobilising faecal
11 sludges and other hazardous materials leading to both direct and indirect exposure via food and contaminated
12 objects and surfaces and pollute streams and waterbodies (Howard et al., 2016; Braks and de Roda Husman,
13 2013; Bornemann et al., 2019). Floods also damage infrastructure; toilets, pits, tanks and treatment systems
14 are all vulnerable (Sherpa et al., 2014; UNICEF and WHO 2019).

15

16 Sanitation systems coupled with floodwater management are at risk of damage and capacity exceedance
17 from high rainfall (Thakali, Kalra and Ahmad, 2016; Kirshen et al., 2015; Dong, Guo and Zeng, 2017). In
18 England, the number of water and wastewater treatment plants at risk of flooding is projected to increase by
19 33% under a 4oC scenario (Sayers et al., 2015), but risks are generally increasing for both formal and
20 informal urban sanitation systems (Howard et al., 2016).

21

22 6.2.4.6 Natural and Ecological Infrastructure

23

24 Urban ecological infrastructure includes green (i.e., vegetated), blue (i.e., water-based), and grey (i.e., non-
25 living) components of urban ecosystems (Li et al., 2017). While land cover change from urbanization
26 directly reduces the extent of natural and ecological infrastructure (e.g. Lin, Meyers and Barnett, 2015),
27 notable risks arise from climate drivers. Recent research particularly highlights future climate impacts on
28 coastal natural infrastructure ­ including beaches, wetlands, and mangroves ­ which cause significant
29 economic losses from property damage, decreasing tourism income, as well as loss of natural capital and
30 ecosystem services. Research on climate risks to urban trees and forests is comparatively limited. Instead,
31 urban vegetation and green infrastructure are most often cast as adaptation strategies to reduce urban heat,
32 mitigate drought, and provide other ecosystem benefits (see 6.3.2).

33

34 Coastal natural infrastructure is exposed to sea level rise, wave action, and inundation from increasing storm
35 events (See also CCP 2.2.1). Beaches, in particular, are highly exposed to climate-induced coastal erosion
36 ((Toimil et al., 2018); CCP2). Research from settlements across coastal Southern California, USA, show that
37 67% of all beaches may completely erode by 2100 (Vitousek, Barnard and Limber, 2017). Coastal zones
38 across Cancún, Mexico, are exposed to a combination of sea level rise and tropical hurricanes, further
39 exacerbated by urban development patterns blocking natural sediment replenishment to beaches (Escudero-
40 Castillo et al., 2018). In another case, beach erosion along the heavily urbanized Valparaíso Bay, Chile, is
41 heightened by El Nińo Southern Oscillation (ENSO) events, which in the past have caused an additional 15-
42 20cm in mean sea level rise (Martínez et al., 2018).

43

44 Wetlands, mangroves, and estuaries ­ which tend to be heavily urbanized areas ­ are highly at risk from sea
45 level rise and changing precipitation (Green et al., 2017; Feller et al., 2017; Alongi, 2015; Osland et al.,
46 2017; Chow, 2018; Godoy and Lacerda, 2015). Sea level rise is a concern for wetlands and mangroves
47 across coastal urban Asia, the Mississippi Delta (USA), and low lying small island states (Ward et al.,
48 2016b). Research on the highly urbanized Yangtze River estuary in China shows that soil submersion and
49 erosion from sea level rise, compounded by land conversation to agriculture and urban development, will
50 cause all tidal flats to disappear by 2100 (Wu, Zhou and Tian, 2017). In another example, sea level rise and
51 high rates of tidal inundation have increased overall salinity in the San Francisco Bay-Delta estuary,
52 threatening the ecosystem's ability to support biodiversity (Parker and Boyer, 2019).

53

54 Research on climate risks to urban trees and forests highlight direct impacts from extreme temperatures,
55 precipitation, wind events, and sea level rise, as well as exposure to other hazards such as air pollution, fires,
56 invasive species, and disease (Ordóńez and Duinker, 2014). Since the 1960s, climate change has enabled
57 growth of urban trees, supported by longer growing seasons, higher atmospheric CO2 concentrations,

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 1 reduced diurnal temperature range (Pretzsch et al., 2017), as well as increased fertilization through urban-
 2 enhanced nitrogen deposition (Decina, Hutyra and Templer, 2020). However, these trends may change in the
 3 future as further warming and decreasing water supply may depress tree fitness, thus enabling more pests
 4 (Dale and Frank, 2017).

 5

 6 Climate risks to urban natural and ecosystem infrastructure entail significant economic costs. For example, in
 7 2012, Hurricane Sandy led to total losses of up to US$6.5 million to the New York City region's low-lying
 8 salt marshes and beaches (Meixler, 2017). Research from coastal settlements across Catalonia, Spain, shows
 9 significant levels of tourism loss (which contribute to 11.1% of the region's GDP), infrastructure damage,
10 and natural capital loss attributed to inundation and erosion of beaches, which are projected to retreat by -0.7
11 meters per year given current sea level rise projections of 0.53 to 1.75 meters by 2100 (Jiménez et al., 2017).

12

13 6.2.4.7 Health systems infrastructure

14

15 Healthcare facilities (hospitals, clinics, residential homes) will suffer increasing shocks and stresses related
16 to climate variability and change (Corvalan et al., 2020). Some may be sudden shocks from extreme weather
17 events, which both threaten the facility, staff and patients and increase the number of people seeking health
18 care. There are extensive reports of health facilities being damaged after major floods and windstorms (e.g.
19 2010 floods in Pakistan, Hurricane Sandy in the US) which can be further exacerbated by power and water
20 supply failures (Powell, Hanfling and Gostin, 2012). Disruption to services may persist for many months due
21 to damage to buildings, loss of drugs and equipment, and damaged transport infrastructure significantly
22 increasing travel time for patients (Hierink et al., 2020). The impacts of climate change on the health of
23 residents of `slum' settlements will also compound the existing health burdens faced by these individuals,
24 including infectious disease and other environmental public health concerns (Lilford et al., 2016; Mberu et
25 al., 2016).

26

27 6.2.5 Compound and Cascading Risks in Urban Areas

28

29 Compound events can be initiated via hazards such as single extreme events, or multiple coincident events
30 overlapping and interacting with exposed urban systems or sectors as compound climate risks (Leonard et
31 al., 2014; Pörtner et al., 2019; Piontek et al., 2014). Hydrometeorological hazards - such as extreme
32 precipitation from tropical cyclones, fronts, and thunderstorms - often combine with storm surges and
33 freshwater discharge leading to high compound risks at exposed settlements (Zheng, Westra and Sisson,
34 2013; Chen and Liu, 2014; Ourbak and Magnan, 2018; Dowdy and Catto, 2017). The compounding effect
35 between these hydrometeorological hazards suggest that the combined impact of these events are greater
36 than each of these variables on its own, and can amplify risks in affected settlements (Kew et al., 2013;
37 Vitousek et al., 2017). These risks are concentrated in coastal cities exposed to sea level rise and severe
38 storms (van den Hurk et al., 2015; Wahl et al., 2015; Paprotny et al., 2018b; Lagmay et al., 2015), or in
39 settlements located in valleys prone to slope failure, such as the 2013 Uttarakhand floods and landslides
40 arising from extreme precipitation and glacial lake outbursts along the Mandakini river in India (Ziegler et
41 al., 2016; Barata et al., 2018).

42

43 Cascading climate events occur when an extreme event triggers a sequence of secondary events within
44 natural and human systems that causes additional physical, natural, social or economic disruption. The
45 resulting impact can be significantly larger than the initial hazard (Pörtner et al., 2019). Each step in a risk
46 cascade can generate direct (immediate impacts) and secondary (consequential impacts) losses. Risks from
47 these cascading impacts are complex and multidimensional (Hao, Singh and Hao, 2018; Zscheischler and
48 Seneviratne, 2017). For instance, combined droughts and heat waves increases risks of urban water scarcity
49 (Miralles et al., 2019; Gillner, Bräuning and Roloff, 2014; Gill et al., 2013), as well as increasing wildfire
50 extent and lowering snowpack conditions that affected peri-urban settlements adjacent to forested areas as
51 observed in California during the 2014 drought (AghaKouchak et al., 2014). Similarly, heat waves can
52 increase the risk of mortality associated with air pollution (see 7.2.2.5).

53

54 Urban areas and their infrastructure are susceptible to both compounding and cascading risks arising from
55 interactions between severe weather from climate change and increasing urbanization (medium evidence,
56 high agreement) (Moretti and Loprencipe, 2018; Markolf et al., 2019). Risks are complex and
57 multidimensional, and can significantly amplify the impact of single events across space, scale, and time.

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 1 Impacts are determined by the magnitude of urban vulnerability and/or the interdependence of urban critical
 2 infrastructure (Pescaroli and Alexander, 2018; Zuccaro, De Gregorio and Leone, 2018). Poorer and wealthier
 3 settlements and cities are then both at risk from compound and cascading risks though potentially through
 4 contrasting mechanisms. For richer and poorer cities, managing climate risk as part of compound and
 5 cascading risks that can also include technological, biological, and political risks places renewed emphasis
 6 on investment in generic capabilities that reduce vulnerability and on risk monitoring capability to track and
 7 respond to impacts across infrastructures and places (low evidence, high agreement). Considering climate
 8 risk and managing such risk as part of complex, compounding and/or cascading risks is in its infancy but
 9 rapidly being accepted as necessary especially when considering the wider poverty and justice implications
10 of climate change arising from differentiated vulnerability in cities.

11

12 Compound risks to key infrastructure in cities have increased from extreme weather (medium evidence, high
13 agreement), such as from urban flooding from extreme precipitation and storm surges disrupting transport
14 infrastructure and networks, e.g. (Mehrotra et al., 2018); See also San Juan case study in this chapter), ICT
15 networks e.g. underground cables or transmission towers (Schwarze et al., 2018), and energy generation
16 from power plants (Marcotullio et al., 2018).

17

18 The increased risk arises not just from greater exposure from climate events impacting cities, but is also
19 magnified by low adaptive capacity that can arise from intra-urban variations in infrastructure quality. For
20 instance, infrastructure within expanding informal settlements are associated with deficiency in materials,
21 structural safety, and a lack of accessibility. These areas are often located in the most risk-prone urban areas
22 in developing nations that are vulnerable to compound hazards (Dawson et al., 2018). Further these risks can
23 be exacerbated from complications arising from local vs. national governance and/or regulations related to
24 hazard management (Garschagen, 2016; Castán Broto, 2017).

25

26 Projected global compound risks will increase in the future, with significant risks across energy, food, and
27 water sectors that likely overlap spatially and temporally while affecting increasing numbers of people and
28 regions particularly in Africa and Asia (high confidence) (Hoegh-Guldberg et al., 2018). In cities, the
29 prevalence of compounding risks therefore necessitates methodologies accounting for nonstationary risk
30 factors.

31

32 Secondary impacts occurring sequentially after an extreme hazard can severely affect disaster management
33 especially in complex urban systems (robust evidence, high agreement). Over time, relatively small
34 perturbations can cascade outward from a primary failure, triggering further failures in other dependent parts
35 of the network some distance away from the primary failure (Penny et al., 2018). In some cities, such as
36 those prone to compound flood hazards, these dependent network parts can be dams, levees, or other critical
37 flood protection infrastructure that are essential for managing these cascading risks (Serre and Heinzlef,
38 2018; Fekete, 2019). Failure of these infrastructure systems can result in sequential failures in urban
39 transport (Zaidi, 2018), energy networks (Sharifi and Yamagata, 2016), urban biodiversity (Solecki and
40 Marcotullio, 2013) and so-called na-tech disasters - when natural hazards trigger technological disasters
41 (Girgin, Necci and Krausmann, 2019). This risk cascade can propagate more widely by stopping flows of
42 people, goods, and services, with economic consequences beyond urban areas (Wilbanks and Fernandez,
43 2014).

44

45 Compound and cascading climate risks require a different way of accounting for cumulative hazard impacts
46 in urban areas (medium evidence, high agreement). There is emerging literature calling for analysis on
47 interactions between individual and interrelated climate extremes with complex urban systems, so as to
48 ascertain how urban and key infrastructural vulnerabilities can be identified and managed in a warming
49 world (Butler, Deyle and Mutnansky, 2016; Gallina et al., 2016; Moftakhari et al., 2017; Zscheischler et al.,
50 2018; Baldwin et al., 2019; Pescaroli and Alexander, 2018; Yin et al., 2017; AghaKouchak et al., 2020), as
51 well as in managing adaptation for present and future pandemics e.g. COVID-19 (Pelling et al., 2021;
52 Phillips et al., 2020b).

53

54 In term of policy, case studies from London's resilience planning process stressed the need for intermodal
55 coordination, hazard risk and infrastructure mapping, clarifying tipping points and acceptable levels of risk,
56 training citizens, strengthening emergency preparedness, identifying relevant data sources, and developing
57 scenarios and contingency plans (Pescaroli, 2018). Others also note the utility of a systems approach to

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 1 analyzing risks and benefits, including considerations of potential cascading ecological effects, full life cycle
 2 environmental impacts, and unintended consequences, as well as possible co-benefits of responses
 3 (Ingwersen et al., 2014). Lowering these risks requires urban stakeholders to reduce urban vulnerability by
 4 going beyond linear approaches to risk management (medium evidence, high agreement).

 5

 6 6.2.6 Impacts and Risks of Urban Adaptation Actions

 7

 8 Planning and implementing climate adaptation in cities and settlements can be hampered by incomplete
 9 scientific knowledge, a lack of awareness of cascading impacts (and residual risks), mismanagement of
10 actions, human capacity and financing deficits, as well as opportunities for eroding long-term sustainable
11 development priorities (Juhola et al., 2016). These tensions can become acute in fragile and conflict affected
12 states (see Box 6.3). It is important to differentiate between the climatic drivers of risk and social drivers that
13 may compound risk exposures and experiences (Brown, 2014; Nightingale et al., 2020), especially since
14 technically- and scientifically-informed adaptation actions can be redirected depending on socioeconomic,
15 political, or cultural conditions on the ground (Eriksen, Nightingale and Eakin, 2015). The implementation of
16 adaptation ­ whether by government, private sector, or civil society actors ­ can therefore lead to
17 unanticipated and unintended amplification of political, economic and ecological risks (Swatuk et al., 2020).
18 Many cities are still in the phase of piloting or testing out appropriate adaptation actions, although there is
19 emerging consensus that adaptation plans and projects should acknowledge trade-offs, intentionally avoid
20 past development mistakes, not lock-in detrimental impacts or further risks arising from implementation, and
21 explicitly anticipate the risks of maladaptation in decision-making (Magnan et al., 2016; Gajjar, Singh and
22 Deshpande, 2019). Maladaptation describes actions that lead to increased vulnerability or risk to climate
23 impacts or diminish welfare. Urban examples include green gentrification which offers nature based
24 solutions to the few, social safety nets that promote risk inducing subsidies. Whether an action is maladapted
25 can depend on context, e.g. air conditioning can reduce risk for the individual but is maladaptive at a societal
26 level (see 6.3.4.2). It is informed by process ­ corruption can distort processes and generate maladaptation
27 (see 6.4.5.2). Climate Resilient Development raises the ambition for adaptation actions so that it is also
28 possible to describe actions that do not also enhance climate mitigation and sustainable development
29 outcomes as maladaptive (see 6.4.3.1). This section assesses three broad categories of risk arising from
30 downstream adaptation actions, including interventions that transfer vulnerability across space and time,
31 plans that yield socioeconomically exclusionary outcomes, and actions that undermine long-term sustainable
32 and resilient development priorities.

33

34

35 [START BOX 6.3 HERE]

36

37 Box 6.3: Climate Change Adaptation for Cities in Fragile and Conflict Affected States

38

39 Larger cities may be the most stable administrative entities in states affected by conflict. Even here ability to
40 plan and deliver adaptation can be hampered. Extending into urban areas within stable states, alienation and
41 loss of trust between local populations and the state can be exacerbated by top-down adaptation planning and
42 delivery; socially and spatially uneven adaptation investment., and in the economic and administrative limits
43 of government that can lead to some places being excluded from formal planned investment (high
44 confidence) (see 6.3 and 6.4). These pathways for exclusion can combine amongst already marginalized and
45 low-income populations where trust in government agencies may already be low (Rodrigues, 2021).

46

47 Climate change can be a threat multiplier in cities and urban regions, exacerbating existing human security
48 tension (limited evidence, medium agreement) (Froese and Schilling, 2019; Flörke, Schneider and
49 McDonald, 2018; Rajsekhar and Gorelick, 2017). Where conflict or administrative tensions extend beyond
50 cities, adapting regional infrastructure systems that underpin urban life is challenging for example where
51 elements of networked infrastructure are under the control of conflicting political interests. This has been
52 noted for the water sector (Tänzler, Maas and Carius, 2010). Coordinating political processes is a major
53 challenge even for industrialized countries with adequate administrative capacity. In post-conflict societies ,
54 the difficulties of coordination for urban planning are disproportionately greater (Sovacool, Tan-Mullins and
55 Abrahamse, 2018).

56

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 1 In planning adaptation measures in cities, conflict-sensitive approaches to ensure participatory methods
 2 (Bobylev et al., 2021) can avoid adaptation being a polarising activity (Tänzler, Maas and Carius, 2010;
 3 Tänzler, 2017). Adaptation can provide a common goal reaching across political differences and be a part of
 4 building political trust and local cooperation between alienated communities (Tänzler, Maas and Carius,
 5 2010). Peacebuilding programmes led by government or civil society are typically concerned with the short-
 6 term and framed by socioeconomic policy, integrating the longer-term view and engineering-technical
 7 expertise for adaptation is a challenge (limited evidence, medium agreement) (Ishiwatari, 2021).

 8

 9 [END BOX 6.3 HERE]

10

11

12 Downstream impacts occur because adaptive capacity is often unequally distributed across sectors and
13 communities (Matin, Forrester and Ensor, 2018; Makondo and Thomas, 2018). In cities and settlements,
14 adaptation interventions can displace ecological impacts to more vulnerable areas or directly lead to
15 socioeconomically exclusionary outcomes (Anguelovski et al., 2016), particularly when adaptation plans and
16 actions are primarily assessed through the prism of economic and/or financial viability (Shi et al., 2016;
17 Klein, Juhola and Landauer, 2017). As a result, adaptation actions make only minimal contributions to the
18 reduction of vulnerability ­ as the increased vulnerability of excluded communities more than offsets the
19 decreased vulnerability of more well-off communities. Numerous examples ranging from the mega coastal
20 planning in Jakarta, Indonesia (Salim, Bettinger and Fisher, 2019; Goh, 2019), fragmentation of urban
21 infrastructure intended to promote climate resilience in Manila, Philippines (Meerow, 2017), exclusionary
22 modes of flood control in Săo Paulo, Brazil (Henrique and Tschakert, 2019), strategies to reduce risks in the
23 event of mudslides in Sarno, Italy (D'Alisa and Kallis, 2016), involuntary community relocations in Vietnam
24 (Lindegaard, 2019) and Mozambique (Arnall, 2019) all point to how an economic logic to adaptation can
25 lead to exclusion of lower income, informal, or minority communities in adaptation.

26

27 A specific form of maladaptation is so called green gentrification, this privileges wealthy urban residents in
28 urban greening projects (Rice et al., 2020; Shokry, Connolly and Anguelovski, 2020; Anguelovski, Irazábal-
29 Zurita and Connolly, 2019; Blok, 2020). For example, in Miami-Dade County, Florida, United States,
30 researchers found that adaptation functionality had a positive effect on property values (Keenan, Hill and
31 Gumber, 2018). In New York City and Atlanta, Georgia, United States, research has shown that adaptation
32 investments can increase property values and lead to neighborhood change (Immergluck and Balan, 2018;
33 Gould and Lewis, 2018). In Gold Coast and Sunshine Coast, South East Queensland, Australia, where local
34 communities have a strong preference for waterfront living, local governments are pressured by property
35 developers to protect these coastal zones (Torabi, Dedekorkut-Howes and Howes, 2018). In Lagos, Nigeria,
36 efforts to achieve climate resilience and sustainability through future city practices risk perpetuating the
37 enclosure and commodification of land (Ajibade, 2017). The exclusionary outcomes of some adaptation
38 interventions can therefore further heighten the risk to communities that are socioeconomically more
39 vulnerable. See Section 6.3 for further discussion of equity and justice considerations in local climate
40 adaptation.

41

42 Human behaviour can exacerbate climate impacts ­ for example in the emergence of `last chance
43 tourism'(Lemieux et al., 2018) focused on built cultural heritage at risk from climate change associated
44 events including from decay or even total loss generated by increased flooding and sea-level rise (Camuffo,
45 Bertolin and Schenal, 2017) and water infiltration from post-flood standing water (Camuffo, 2019). Last
46 chance tourism can lead to increased touristic interest over a short time horizon and to precarious economic
47 conditions, which can lead to further accelerated degradation cultural heritage sites already at-risk from
48 climate change.

49

50 Finally, some adaptation policies or actions can erode the preconditions for sustainable and resilient
51 development by indirectly increasing society's vulnerability (Neset et al., 2019; Juhola et al., 2016).
52 Mandates to mainstream adaptation into existing development logics and structures perpetuates
53 development-as-usual, reinforcing technocratic forms of local governance and locking-in structural causes of
54 marginalization and differential vulnerability (Scoville-Simonds, Jamali and Hufty, 2020). Adaptation policy
55 examples include: Australia's adaptation policy focus on financial strategies, preference for business-as-
56 usual scenarios and incremental change will not contribute to transformative change (Granberg and Glover,
57 2014); Surat, India, where a focus on adapting industries and economically important assets in the city can

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 1 divert policy attention away from general social equity and urban sustainability priorities (Chu, 2016; Blok,
 2 2020); Cambodia where conflict between adaptation practitioners and local communities and non-
 3 compliance with regulatory safeguards led to conflict and potential for maladaptation (Work et al., 2018).
 4 Finally, although insurance has the potential to incentivize practices to reduce risks ­ including through
 5 measures to reduce premiums (see Section 6.4.5 for additional details) ­ researchers of insurance-led
 6 adaptation actions have argued that since insurance regimes privilege normality, they tend to structurally
 7 embed risky behavior and inhibit change (O'Hare, White and Connelly, 2016). All of these examples
 8 illustrate how incremental strategies that rely on business-as-usual actions can further entrench unequal and
 9 unsustainable development patterns in the long-term. There are also significant limits to urban adaptation
10 (see Section 6.4) with consequential impacts on human wellbeing.

11

12 Table 6.4 lists a selection of key risks (broadly defined as have severe outcomes common to a majority of
13 cities) identified in our assessment of urban impacts and risks in this section. It provides a description of the
14 consequences of the risk that would constitute a severe outcome, as well as the hazard, exposure and
15 vulnerability conditions contributing to its severity. It also provides adaptation options identified and
16 elaborated on in Section 6.3 as having the highest potential for reducing the risk, and an assessment of the
17 confidence in the judgement that this risk could become severe. This table is also reflected in Chapter 16.5.1,
18 and the methodology is described in Table SM16.5.1.

19

20

21 Table 6.4 Key Risks to Cities, Settlements and Infrastructure

         Synthesis of key risks for cities, settlements, and key infrastructure

Key risk   Geograp  Consequen     Hazard        Exposure       Vulnerabili   Adaptation     Confidenc    Chapt
           hic      ce that       conditions    conditions     ty            options with   e in key     er &
           region   would be      that would    that would     conditions    highest        risk         sectio
                    considered    contribute    contribute to  that would    potential for  identificat  n
                    severe, and   to this risk  this risk      contribute    reducing       ion
                    to whom       being         being severe   to this risk  risk
                                  severe                       being
                                                               severe

Risk to    Global Increased Substantial Large                  Changing Nature-             High         6.2,
populatio
n from     but      heat stress, increase in increases in demograph based                   confidenc 6.3
increased
heat       higher mortality frequency exposure, ics from solutions e, high

           risk in and            and           particularly aging           e.g. urban evidence

           temperat morbidity duration of in urban             population greenery at &

           e and events           extreme areas,               s, potential multiple        agreement

           tropical from          heat events, (6.2.3)         for           spatial

           cities urbanizatio exacerbate driven by persistent scales;

           (6.2.3.1) n and        d by urban population poverty, vegetation;

                    climate heat island growth,                slow          shading;

                    change. effects.            changing penetration lower

                    Increased (6.2.3.1) demographi and                       energy

                    health        Concentrati cs, and          increasing costs; green

                    risks and on of a           projected cost of air roofs;

                    mortality mixture of urbanization conditionin community

                    in elderly extreme          patterns.      g, and        gardens

                    population; heat and Urbanizatio inadequate (6.3.3.1)

                    vulnerabili humidity n increases improveme enhanced

                    ty of the (6.2.3.1) annual mean nts in                   space

                    young to                    surface air public           conditioning

                    heat,                       temperature health           in buildings;

                    (6.2.3.1)                   by more        systems. broader

                                                than 1°C (6.2.3.1) access to

                                                Correlation Inadequate public health

                                                between        housing systems for

                                                rising         and           most

                                                temperature occupation vulnerable

                                                s and          s with        populations.

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                                                 increased      exposure     Less
                                                 heat           to heat      economic
                                                 capacity of    (6.2.3.1)    stress on
                                                 urban                       residents
                                                 structures,                 through
                                                 anthropogen                 utilities,
                                                 ic heat                     especially
                                                 release and                 electricity
                                                 reduced                     (6.2.3.1)
                                                 urban                       Tree
                                                 evaporation                 planting in
                                                 (6.2.3.1)                   communities
                                                                             that lack
                                                                             urban
                                                                             greening
                                                                             (6.3.3.1)

Urban        Global,  Damage to    Substantial   Large          Costly       Early          High       6.2,
infrastruct  but      key urban    increase in   increases in   maintenan    warning        confidenc  6.3,
ure at risk  higher   infrastruct  frequency     exposure,      ce of        systems,       e, high    CCP2
of damage    risk in  ure (e.g.    and           particularly   protective   Adaptive       evidence
from         coastal  buildings,   intensity of  in urban       infrastruct  Social         &
flooding     cities   transport    extreme       areas, driven  ure,         Protection     agreement
and severe            networks,    precipitatio  by             downstrea    (ASP) to
storms                and power    n (6.2.3.2)   population     m levee      reduce
                      plants) and  from          growth,        effects,     vulnerable
                      services     severe        changing       and          populations,
                      from flood   weather       demographi     increased    nature-based
                      events,      events and    cs, and        concentrati  solutions
                      particularl  tropical      projected      ons of       e.g. in
                      y high risk  cyclones      urbanization   coastal      sponge cities
                      within       contributin   patterns       urban        to enhance
                      coastal      g to pluvial  with a         population.  flood
                      cities,      and fluvial   geographica    Little       protection
                      especially   floods,       l focus in     investment   and regulate
                      those        which are     coastal        in drainage  storm- and
                      located in   exacerbate    regions.       solutions    floodwaters-
                      low          d by long-    Flooding is    (6.2.3.2)    this can be
                      elevation    term sea      exacerbated                 improved
                      coastal      level rise    both by                     through
                      zones        and           encroachme                  reduced risk
                      (6.2.3.2)    potential     nt of urban                 unto
                                   land          areas into                  vulnerable
                                   subsidence    areas that                  urban
                                   (6.2.3.2)     retain water,               systems
                                                 and lack of                 such as
                                                 infrastructur               stormwater
                                                 e such as                   management
                                                 embankmen                   , sustainable
                                                 ts and flood                urban
                                                 walls                       drainage
                                                 (6.2.3.2)                   system, etc.
                                                                             (6.2.3.2)
                                                                             Green
                                                                             infrastructur
                                                                             e can be
                                                                             more
                                                                             flexible and
                                                                             cost
                                                                             effective for
                                                                             providing
                                                                             flood risk

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                                                                   reduction
                                                                   (6.3.3)

Populatio  Cities Water           Projections Large         Greater Demand and High          6.2,
n at risk
from       located shortages of more increases in water            supply side confidenc 6.3
exposure
to urban   in    in urban frequent exposure, demand management e, high
droughts
           regions areas, and and             particularly from urban strategies evidence

           with  restricted prolonged in urban              population that include &

           high  access to drought areas, driven s from in- incorporatio agreement

           drought water          events      by            migration n of

           exposure resources potentially population and key indigenous/l

           , (e.g., to            compounde growth,         economic ocal

           Europe, vulnerable d with heat changing sectors, knowledge

           South population wave              demographi and       and

           Africa, s and low- hazards, cs, and              inefficient practices,

           Australia income and land projected or                  equitable

           ,)    settlements subsidence urbanization ineffective access to

                 . People from                patterns.     water  water. Better

                 living in coastal            Limitations resource water

                 urban            cities that of            manageme resource

                 areas will extract           engineered nt.       management

                 be exposed groundwate water                (6.2.3.3) will increase

                 to water r. Climate infrastructur                 quality of

                 scarcity drivers             e is also            water

                 from             (warmer exposed by               available.

                 severe           temperatur flash                 More

                 droughts es and              droughts             beneficial

                 (6.2.3.3). droughts) (6.2.3.3).                   physical and

                 Increased along with Settlements                  social

                 environme urbanizatio are                         teleconnecti

                 ntal health n processes increasingly              ons to bring

                 risks when (land use dependent                    mutual

                 using            changes, on imported             benefit of

                 polluted migration water                          water

                 groundwat to cities, resources by                 resources

                 er (6.2.3.3) and             locales that         between

                                  changing may also be             regions

                                  patterns of exposed to           (6.2.3.3)

                                  water use) drought risk

                                  contribute (6.2.3.3)

                                  to

                                  additional

                                  risks

                                  (6.2.3.3)

Health Global, Increased Increased Large                    High   Enhanced High             6.2,

risks from in cities mortality emissions increases in proportion monitoring confidenc 6.3

air        located and            of          exposure, of young of air quality e,

pollution in     morbidity pollutants particularly or aging in rapidly medium

exposure Africa, events           from        in urban      population developing evidence

in cities South from              anthropoge areas, driven s       cities,           &

           Asia, the respiratory nic (e.g. by               vulnerable investment agreement

           Middle -related transportati population to              in air

           East and illnesses on, electric growth,          respiratory pollution

           East  and co- power                changing illness,    controls e.g.

           Asia  morbidities generation, demographi potential stricter

                 towards large                cs, projected for    emissions

                 vulnerable industries, urbanization persistent regulations,

                 urban            indoor      patterns, and poverty, and

                 population burning of demand for advection increased

                 s, arising fuel, and energy                of     GHG

                 from             commercial combined pollutants emissions

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               PM2.5 and          and          with weak      from        controls
               tropospheri        residential  regulations    upwind,     resulting in
               c ozone            sources)     for            ex-urban    co-benefits
               exposure           and          emissions      areas, and  with air
                                  biogenic     control (6.2.  stay in     quality
                                  (e.g.        3.4)           shelter     improvemen
                                  forests,                    policies    ts.
                                  windblown                   from        Increase in
                                  dust, and                   COVID-19    trees or
                                  biomass                     (Box 6.4;   vegetated
                                  burning)                    6.2.5)      barriers with
                                  emissions                               low VOC
                                                                          emissions,
                                  Potential                               low allergen
                                  for severe                              emissions,
                                  compound                                and high
                                  risks                                   pollutant
                                  arising                                 deposition
                                  from                                    potential to
                                  droughts                                reduce
                                  and                                     particulate
                                  wildfire.                               matter and
                                                                          maximize
                                  Projections                             adaptation
                                  for                                     benefits
                                  frequency                               (6.3.3.2)
                                  of
                                  meteorolog
                                  ical
                                  conditions
                                  are
                                  expected to
                                  severe
                                  PM2.5
                                  concentrati
                                  ons
                                  (6.2.3.4)

Health Cities Increased Decreased Large                       Costly      Investment High          6.2,

risks from located environme regional increases in maintenan in well-                    confidenc 6.3

water  in      ntal health precipitatio exposure, ce of                   regulated e,

pollution regions risks when n and             particularly protective water             medium

exposure with  using              changes in in urban         infrastruct sections;      evidence

and    high    polluted runoff and areas, driven ure.                     wastewater &

sanitation drought groundwat storage           by             Sanitation treatment agreement

in cities exposure er (6.2.3.3) from           population systems plants;

       resulting Vulnerabili droughts growth,                 coupled pumping

       in      ty of users impairs the changing with flood stations.

       polluted such as quality of demographi water                       Reducing

       water women; water                      cs, and        manageme impacts of

               children; available. projected nt are at floods on

               the elderly; Less runoff urbanization risk of              sanitation

               ill or             to           patterns.      damage      infrastructur

               disabled freshwater Low flows and                          e through

               (6.3.4.6) rivers can from                      capacity active

                                  increase drought can exceedanc management

                                  salinity, lead to           e from      such as

                                  concentrate sedimentatio high           reducing

                                  pathogens, n, increase rainfall         blockage in

                                  and          pollutant (6.2.5.8) sewer

                                  pollutants concentratio                 infrastructur

                                  (6.2.3.3) n and                         e (6.3.4.6)

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                                  blocking of    Adaptive
                                  sewer          planning;
                                  infrastructur  integration
                                  e networks     of measures
                                  (6.2.5.8).     of climate
                                                 resilience;
                                                 improved
                                                 accounting
                                                 and
                                                 management
                                                 of water
                                                 resources
                                                 (6.3.4.6)

 1 Table Notes:
 2 Following Chapter 16, the severity of a risk or impact is a subjective judgment based on a number of criteria. Key Risks
 3 are `potentially' severe because, while some could already be severe now, more typically they may become so over time
 4 due to changes in the nature of the climate-related hazards and/or of the exposure and/or vulnerability of societies or
 5 ecosystems to those hazards. They also may become severe due to the adverse consequences of adaptation or mitigation
 6 responses to the risk.

 7

 8

 9 6.3 Adaptation Pathways

10

11 6.3.1 Introduction

12

13 Adaptation pathways are composed of sequences of adaptation actions connected through collaborative
14 learning with the possibility of enabling transformations in urban and infrastructure systems (Werners et al.,
15 2021). Individual adaptation actions co-evolve with risks (see Section 6.2) and development processes
16 (Section 6.4) to compose more or less planned adaptation pathways, that can include a range of unanticipated
17 outcomes. This section engages with this complexity by approaching adaptation through the notion of
18 infrastructure. The adaptation options for individual infrastructure systems are reviewed, and in Section 6.4
19 brought together through assessment of cross-cutting enabling conditions. Interpreted broadly, infrastructure
20 includes the social systems, ecological systems and grey/physical systems that underpin safe, satisfying and
21 productive life in the city and beyond (Grimm et al., 2016). Social infrastructure includes housing, health,
22 education, livelihoods and social safety nets, cultural heritage/institutions, disaster risk management and
23 security and urban planning. Ecological infrastructure includes nature-based services: temperature
24 regulation, flood protection and urban agriculture. Grey, or physical infrastructure includes energy, transport,
25 water and sanitation, communications (digital), built form and solid waste management. Framing
26 infrastructure in this way enables an assessment of adaptation that is not constrained to the administrative
27 boundaries of urban settlements, but also includes the flows of material, people and money between urban,
28 peri-urban and more rural places and can include adaptation actions deployed by government, individuals
29 and the private sector. Recognising the complexity of adaptation and the research literature that reaches
30 beyond individual infrastructural domains, the section also reviews urban adaptation through the cross-
31 cutting lenses of equity and mitigation. Section 6.4 assesses the enabling environment (political will,
32 governance, knowledge, finance and social context) that shapes specific adaptation contexts and futures.

33

34 6.3.2 The Adaptation Gap in Cities and Settlements

35

36 The adaptation gap is difference between the ability to manage risk and loss and experienced risk and loss
37 (Chen et al., 2016; UNEP, 2021). It describes both levels of capacity and residual risk. Figure 6.4 presents an
38 analysis by IPCC World Region for urban populations and current levels for risk and loss. The analysis seeks
39 to draw out equity considerations by comparing the poorest and wealthiest quintiles for each region and for
40 adaptation to the direct impacts of flooding and heatwave but also impacts felt in cities that include climate
41 change impacts on supply chains ­ water and food security. Figure 6.4 should not be used to compare
42 regions but can be used to contrast adaptation gaps by hazard type within regions.

43

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 1 The key finding from Figure 6.4 is that for all urban populations both currently deployed and currently
 2 planned adaptations are not able to meet current levels of risk associated with climate change. Even if all
 3 conceivable adaptation was to be deployed the majority of risks faced by the urban rich and poor today
 4 would not be fully resolved. This emphasizes clearly the fundamental importance of climate change
 5 mitigation to avoid urban risk and loss.

 6

 7 The urban adaptation gap is also found to be unequal. The poorest quintile has a larger adaptation gap than
 8 the richest quintile. Reported inequality in the application of urban adaptation is greatest in North, East and
 9 Southeast Asia reflecting rapid urbanization in this region. Reported inequality is lowest in Europe and
10 Australasia. Observed inequalities indicate that the markets, government actions and civil society
11 investments available to reduce vulnerability and risk amongst the poor have not been observed to offset
12 inequalities based on individual and household capacities.

13

14 There is some catch-up as analysis moves through actually deployed to planned and all conceivable
15 deployment ­ particularly for water and food security - but even here inequality in risk is not fully resolved.
16 Africa and South and Central Asia in particular show considerable disparity in adaptation to urban food
17 security even with all conceivable adaptation. This means that even if all available adaptation was to be
18 deployed inequality in ability to adapt to climate change would remain. This highlights the significance of
19 addressing underlying inequalities in development that shape differential vulnerability (see 6.2.3.1, 6.2.3.3,
20 6.3.5.1, 6.4) as part of vision and action on reducing risk to climate change so that no one is left behind.

21

22 Some hazard types and regions show strong capacity to close the adaptation gap if all planned adaptation
23 was to be deployed: for example, Europe for heatwave and Europe and Central and South America for
24 riverine and coastal flooding (particularly for wealthier populations). This reveals capacity within the current
25 approaches to climate risk management, but also highlights the importance of resolving challenges that
26 prevent planned adaptation from being deployed and deployed equitably.

27

28

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 1

 2 Figure 6.4: The Urban Adaptation Gap. Notes: This is a qualitative assessment presenting individual, non-comparative
 3 data for world regions from 25 AR6 CLAs and LAs, the majority from regional chapters. Respondents were asked to
 4 make expert summary statements based on the data included within their chapters and across the AR6 report augmented
 5 by their expert knowledge. Multiple iterations allowed opportunity for individual and group judgement. Urban
 6 populations and risks are very diverse within regions making the presented results indicative only. Variability in data
 7 coverage leads to the overall analysis having medium agreement ­ medium evidence. Major trends identified in 6.3.1 at
 8 least meet this level of confidence. Analysis is presented for current observed climate change associated hazards and for
 9 three adaptation scenarios: (1) current adaptation (based on current levels of risk management and climate adaptation),
10 (2) planned adaptation (assessing the level of adaptation that could be realised if all national, city and neighbourhood
11 plans and policies were fully enacted), (3) transformative adaptation (if all possible adaptation measures were to be
12 enacted). Assessments were made for the lowest and highest quintile by income. Residual risk levels achieved for each
13 income class under each adaptation scenario are indicated by five adaptation levels: no risk, occasional discomfort,
14 occasional impacts on wellbeing, frequent impacts on wellbeing, extreme events and/or chronic risk. The urban
15 adaptation gap is revealed when levels of achieved adaptation fall short of delivering `no risk'. The graphic uses IPCC
16 Regions, and has split Asia into two regions: North and East Asia, and Central and South Asia. Technical support is
17 acknowledged from Greg Dodds and Sophie Wang

18

19

20 6.3.3 Adaptation Through Social Infrastructure

21

22 Social infrastructure refers to social, cultural and financial activities and institutions as well as associated
23 property, buildings and artefacts that can be deployed to reduce risk and recover from loss. This section
24 examines land use planning, livelihoods and social protection, emergency and disaster risk management,
25 health systems, education and communication, and cultural heritage.

26

27 6.3.3.1 Land Use Planning

28

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 1 Land use planning plays a major role in the siting of settlements and infrastructure. In relation to climate
 2 change, it affects whether development takes place in locations that are exposed to hazards; similarly, it
 3 shapes the potential effects that the built environment can have on natural systems. Despite this, generally
 4 speaking, there is limited implementation of zoning and land use measures for climate adaptation from cities
 5 across diverse contexts (robust evidence, high agreement), see for example Maputo (Castán Broto, 2014),
 6 sub-Saharan cities (Dodman et al., 2017) and Amman, Moscow and Delhi (Jabareen, 2015). Certain
 7 countries, such as South Korea, have, however, recently begun to address disaster risk reduction within their
 8 land use planning systems (Han et al., 2019).

 9

10 Conventional zoning regulations (in which only one kind of use is permitted in a given area) and land use
11 planning range in scale from the regional to the local and can be deployed to minimize risks through
12 protection, accommodation, or retreat. Protection entails, in addition to allocating zones for protective urban
13 infrastructure (like seawalls, levees and dykes, and slope revetments), avoidance measures that restrict or
14 prevent urban development (e.g., through growth containment and/or no-build zones). Accommodation
15 involves land use modifications and/or conversions while retreat requires either compulsory or voluntary
16 relocations and may entail buy outs (Butler, Deyle and Mutnansky, 2016; León and March, 2016; Lyles,
17 Berke and Overstreet, 2018). Risk eliminating retreat measures are less widely adopted than other risk
18 reducing zoning and land use measures (Anguelovski et al., 2016; Butler, Deyle and Mutnansky, 2016;
19 Lyles, Berke and Overstreet, 2018). This is attributed to the controversies of relocation and to the
20 complexities of buyouts (Butler, Deyle and Mutnansky, 2016; King et al., 2016).

21

22 Evidence from both richer countries and the Global South reveals that conventional zoning is more effective
23 when governance systems facilitate the implementation of land use policies for climate adaptation that
24 preclude negative human-nature interactions and that curb spatial inequity ­ both of which can trigger
25 climate gentrification and increase the vulnerability of economically disadvantaged groups to climate-related
26 risk (high confidence) (Marks, 2015; Liotta et al., 2020; Keenan, Hill and Gumber, 2018).. Cascading
27 benefits of zoning and land use planning for climate adaptation are associated with the use of soft land cover,
28 green infrastructure and improvement of livability through better conditions for walkability and cycling. This
29 decreases auto-dependency and contributes to health and economic development (by attracting businesses
30 and retail that stimulate economic prosperity and increase property values) (Larsen, 2015; Carter et al.,
31 2015). Such increases in property values have also been observed in zones and areas protected from risks
32 (such as flooding), where it may trigger spatial inequity leading to climate gentrification (Marks, 2015;
33 Votsis, 2017; Votsis and Perrels, 2016; Keenan, Hill and Gumber, 2018).

34

35 Adaptation actions through zoning and land use are more effective when combined with other planning
36 measures (high confidence), for example with ecosystem-based adaptations (e.g., for flood management and
37 curbing the urban heat island effect) (Larsen, 2015; Nalau and Becken, 2018; Perera and Emmanuel, 2018;
38 Anguelovski et al., 2016; Carter et al., 2015; Tsuda and Duarte, 2018; Nolon, 2016); with community-based
39 adaptations (trade-offs and valuations, i.e., which land uses are valued more) (Larsen, 2015; Nalau and
40 Becken, 2018; Perera and Emmanuel, 2018; Anguelovski et al., 2016; Carter et al., 2015; McPhearson et al.,
41 2018; Nolon, 2016); and with built form regulations and codes (León and March, 2016; Yiannakou and
42 Salata, 2017; Perera and Emmanuel, 2018; Straka and Sodoudi, 2019; Larsen, 2015; Nolon, 2016). The
43 imposition of planning-based tools such as scenario planning, flexible zoning, and development
44 incentivisation (among others) has the capacity to influence and encourage these adaptations (United States
45 Environmental Protection Agency, 2017). Local risk-reduction inputs can inform land use adaptation
46 policies (accommodation and/or avoidance, specifically growth containment and no-build zones) that are
47 better integrated within larger urban plans (Lyles, Berke and Overstreet, 2018; Nalau and Becken, 2018;
48 Tsuda and Duarte, 2018) (limited evidence, high agreement).

49

50 Implementation of zoning and land use measures for climate adaptation from cities across diverse contexts
51 remains limited (high agreement, robust evidence) due to a range of challenges. A range of evidence from
52 multiple locations indicates the challenges of mainstreaming land use planning for climate adaptation,
53 including in Bangkok, Thailand (Marks, 2015), Legazpi City and Camalig Municipality in the Philippines
54 (Cuevas et al., 2016; Cuevas, 2016), the United States (Cuevas et al., 2016; Cuevas, 2016), British
55 Columbia, Canada (Stevens and Senbel, 2017), and Australia (Serrao-Neumann et al., 2017). Mainstreaming
56 is hindered by a lack of clarity of implementation strategies for climate adaptation, insufficient funding,
57 competing priorities (especially, among professional planners and politicians), institutional challenges (see

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 1 Jabareen's (2015) study of 20 cities globally) and the need to fill data gaps and continuously update weather
 2 statistics (Oberlack and Eisenack, 2018) (medium evidence, high agreement). At the same time, however,
 3 limited evidence from cities around the world such as: the urban Regions of Stuttgart and Berlin in Germany
 4 (Larsen, 2015), Greater Manchester in the UK (Carter et al., 2015), and Colombo in Sri Lanka (Perera and
 5 Emmanuel, 2018) reveals that risk reduction through zoning and land use can effectively protect and expand
 6 green infrastructure and soft land cover to alleviate pluvial flooding and decrease the urban heat island
 7 effect. This evidence points that one of the primary roles of land-use planning is to guide the development of
 8 the urban form. As such, it underpins and establishes the basis for other infrastructure systems such as
 9 physical infrastructure and nature-based solutions (Morrissey, Moloney and Moore, 2018).

10

11 6.3.3.2 Livelihoods and Social Protection

12

13 Understanding how livelihoods, particularly of the urban poor, are both impacted by climate risk and how
14 they might be strengthened is central to understanding climate adaptation in cities and settlements (Dobson
15 et al. 2015). Rapid urbanization and expanding physical infrastructure do not have a clear relationship with
16 improved outcomes for urban livelihoods of low-income residents (Soltesova et al., 2014). Municipal and
17 national efforts need to be closely aligned with building adaptive capacity of residents themselves, often
18 through community-based adaptation (Soltesova et al., 2014; Dobson, Nyamweru and Dodman, 2015).
19 Social safety nets protect individuals or households from falling below a defined standard of living by
20 providing cash, in kind and other social transfers to fight vulnerabilities (Islam and Hasan, 2019) including
21 those associated with climate change impacts including food shocks. Strengthening the financial and social
22 infrastructure of poor households is a critical component of adaptive and transformative capacity (Haque,
23 Dodman and Hossain, 2014; Ziervogel, Cowen and Ziniades, 2016). Social safety nets are one mechanism
24 for strengthening this capacity.

25

26 Social protection, or social security, is defined as the set of policies and programmes designed to reduce and
27 prevent poverty and vulnerability throughout the life cycle (ILO, 2017). Safety nets are intended to protect
28 vulnerable households from impacts of economic shocks, natural hazards and disasters, and other crises. The
29 UN policy frameworks for sustainable development, including the Sendai Framework for Disaster Risk
30 Reduction 2015-2030, the new Strategic Framework 2018-2030 of the United Nations Convention to
31 Combat Desertification (UNCCD) and UNFCCC, highlight the essential role of social protection in
32 promoting comprehensive risk management (Aleksandrova, 2019). Since the term Adaptive Social
33 Protection was introduced by the World Bank (2015) and the IPCC (2014), Adaptive Social Protection has
34 been an emerging strategic tool to integrate poverty reduction, disaster risk reduction and humanitarian-
35 development into adaptation to climate change (Béné, Cornelius and Howland, 2018; Aleksandrova, 2019;
36 Watson et al., 2016).

37

38 Adaptive Social Protection (ASP) is defined as a resilience-building approach by combining elements of
39 social protection, disaster risk reduction and climate change adaptation, so as to break the cycle of poverty
40 and vulnerability of household by investing in their capacity to prepare for, cope with, and adapt to all types
41 of shocks especially under climate change and other global challenges (Bowen et al., 2020; Ivaschenko et al.,
42 2018). Adaptive Social Protection has been justified as an effective instrument to build household and
43 community resilience to climate extremes and slow-onset climate events like sea level rise and
44 environmental degradation (Schwan and Yu, 2018; Aleksandrova, 2019). In contexts of extreme poverty or
45 climatic extremes, international development organizations, national provisions and market charities are
46 complementary where family and kinship networks are weak and inadequate. To deal with short-term
47 vulnerability to climate shocks, Adaptive Social Protection can act as a crucial complement to risk
48 management tools provided by communities and markets, tools which tend to be insufficient in the face of
49 large or systemic shocks, by providing predictable transfers, developing human capital and diversifying
50 livelihoods (Hallegatte et al., 2016). Adaptive Social Protection can also facilitate long-term change and
51 adaptation by improving education and health levels, as well as providing a proactive approach to managing
52 climate-induced migration in both rural and urban areas (Schwan and Yu, 2018; Adger et al., 2014).

53

54 Many national Adaptive Social Protection programmes are established to cover both rural and urban areas,
55 however, only a small number of researchers pay attention to urban cases (Aleksandrova, 2019). Adaptive
56 Social Protection instruments can be classified into four major types as shown in Table 6.5 (Ivaschenko et
57 al., 2018; ILO, 2017). Adaptive Social Protection can contribute to both incremental and transformative

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1 interventions both at the system level (short-term and long-term coping strategies from communities) and at
2 the beneficiaries' level (vulnerable populations) (Béné, Cornelius and Howland, 2018; World Bank, 2015;
3 Aleksandrova, 2019; Ivaschenko et al., 2018).

4

5

6 Table 6.5 Four categories and examples of adaptive social protection.

   Category Example                                     Urban cases                                   Function

   Social safety  Conditional and unconditional cash    -A targeted asset transfer project for urban  Incremental
   nets (or       transfers, including non-             extreme poor in Dhaka city (Hossain and       adaptation;
   social         contributory pensions and             Rahman, 2018)                                 protective
   assistance)    disability, birth and death           - Emergency food stockpiling in Japan;        measures
                  allowances;                           safety net food stocks in India, Indonesia
   Social         Food stamps, rations, emergency       and Malaysia (Lassa et al., 2019)             Incremental
   insurance      food distribution, school feeding     - Household cash transfer programme in        adaptation and
                  and subsidies;                        contingency planning in Mexico                ex-ante
   Labour         Cash or food for work programmes;     (Ivaschenko et al., 2018)                     prevention
   market         Free or subsidized health services;   - Governmental transfer to hurricane
   policies       Housing and utility subsidies;        affected households in United States          Ex-post
                  Scholarships and fee waivers, etc.    (Bowen et al., 2020)                          protection and
   Livelihood                                           - Non-contributory disability cash benefits   ex-ante
   development    Old age, survivor, and disability     (ILO, 2017)                                   prevention
   measures       contributory pensions;                Old-age social pensions (Ivaschenko et al.,   measures,
                  Occupational injury benefit, sick or  2018)                                         Incremental
                  maternity leave;                                                                    adaptation
                  Health insurance, etc.                Public works and employment protection        Promotive and
                  Unemployment, severance, and          in Africa, Asia cases (World Bank, 2015;      anticipatory
                  early retirement compensation;        ILO, 2017; Ivaschenko et al., 2018)           measures;
                  Training, job sharing, and labor                                                    transformational
                  market services;                      Multiple programs for differing household     adaptation
                  Wage subsidizes and other             needs in Philippines (Bowen et al., 2020)
                  employment incentives, including      Weather-index insurance in Chinese
                  for disabled people, etc.             coastal cities (Rao and Li, 2019); Early
                  Income diversification, employment    warning forecast system and public
                  support, weather-index insurance,     meteorological service information in
                  housing subsidies, post disaster      Beijing (Song, Zheng and Lin, 2021)
                  construction, relocation planning,
                  livelihood shift strategies, etc.

 7

 8

 9 Adaptive Social Protection (ASP) may be very good at reducing extreme poverty by helping to meet
10 individual or household needs but not collective needs to mitigate long-term climate shocks. For example,
11 few programmes consider risk assessment and climate-proof infrastructures as anticipatory measures to
12 foster early action and preparedness (Aleksandrova, 2019; Costella et al., 2017). They therefore need to
13 enable the adoption of forward-looking strategies for long-lasting adaptation (Tenzing, 2020). Some
14 examples from China show social protection can improve adaptive capacity of urban communities with
15 social medical insurance, housing subsidies, weather-index insurance, post disaster construction, relocation
16 planning, livelihood shift strategies, and so on (Pan et al., 2015; Zheng et al., 2018b; Rao and Li, 2019;
17 Song, Zheng and Lin, 2021). However, social protection may lead to maladaptation in urban policy when
18 social security, or similar tools (for example insurance) compensate for exposure deincentivise risk reduction
19 (Grove, 2021). In many developing countries, high concentration of poor and vulnerable groups living in
20 disaster-prone zones of urban centres, new urban dwellers and informal residents are often excluded from
21 community-based networks and social services (Aleksandrova, 2019). Risk transfer tools (like insurance)
22 and risk retention measures (like social safety nets) can avoid and minimise the burden of loss and damage
23 and limit secondary and indirect effects (Aleksandrova, 2019; Roberts and Pelling, 2018).

24

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 1 Inclusive, targeted, responsive and equitable social protection can support long-term transition toward more
 2 sustainable, adaptive and resilient societies (Hallegatte et al., 2016; Shi et al., 2018; Béné, Cornelius and
 3 Howland, 2018; Carter and Janzen, 2018; Adger et al., 2014). Adaptive Social Protection systems can be
 4 cost-effective and equitable when targeting accuracy, timely risk sharing (disaster assistance) and improved
 5 policy coherence. Carter & Janzen (2018) find that the long-term level and depth of poverty can be improved
 6 by incorporating vulnerability-targeted social protection into a conventional social protection system.
 7 Countries at all income levels can set up Adaptive Social Protection systems that increase resilience to
 8 natural hazards, but the systems need to identify cost-benefits, be scalable and flexible to adjust to future,
 9 increasing climate risk. Bastagli (2014) suggested a new design for effective social protection including: (i)
10 increasing the amount or value of transfer; (ii) extending the coverage of beneficiaries; and (iii) introducing
11 payments or new program of social protections. For social protection programmes to contribute more
12 effectively to adaptation, they need to be better coordinated across a range of agencies; better integrated with
13 climate data to anticipate times of need for vulnerable groups; and better aligned with other risk management
14 instruments such as insurance (Agrawal et al., 2019).

15

16 6.3.3.3 Emergency and Disaster Risk Management

17

18 There is growing evidence of the benefits of early warning systems for urban preparedness decision-making
19 and action for climate and weather-related hazards such as cyclones, hurricanes and floods (medium
20 evidence; high agreement) (Lumbroso, Brown and Ranger, 2016; Zia and Wagner, 2015; Marchezini et al.,
21 2017). Climate forecasting is constantly evolving and becoming increasingly accurate. Global organizations
22 such as the World Meteorological Organizations are increasingly focusing on new and emerging
23 technologies such as crowdsourced data collection to support integrated city services and early warning
24 systems (Baklanov et al., 2018). However, while climate forecasting is an increasingly central tool for risk
25 management agencies, a focus on urban areas or key infrastructure is still considerably rare (Lourenço et al.,
26 2015; Nissan et al., 2019; Harvey et al., 2019). The significant rise in urban risks poses significant challenges
27 to humanitarian agencies. Humanitarian responses and local emergency management are vital for disaster
28 risk reduction yet are compromised in urban contexts where it is difficult to confirm property ownership and
29 where renters and informal dwellers are often excluded from decision making and planning (Parker and
30 Maynard, 2015; Maynard et al., 2017). Disaster survivors and growing urban refugee populations are often
31 displaced across the city thereby complicating efforts to track and provide support (Maynard et al., 2017).

32

33 Existing early warning systems remain insufficient and the complexity of urban landforms makes accurate
34 and detailed early warning difficult (medium evidence; high agreement) (Jones et al., 2015)This is
35 particularly the case in low- and middle-income countries (LMICs) where urban centres are often
36 characterized by rapid expansion of interlinked formal and informal human settlements and land use zones.
37 In such contexts, early warning services vary in effectiveness within the same urban centre (Allen et al.,
38 2020c; Rangwala et al., 2018). Often, forecast-based action follows linear structures where forecast
39 information is applied mainly for responding to negative impacts rather than anticipatory decision making
40 and preparation to avoid such impacts (Marchezini et al., 2017). Early warning systems are effective for
41 warning of threshold breaching events including cyclonic activity and riverine flooding but less able to
42 provide localised warning, though capability is rapidly increasing. Probabilistic risk forecasting and forecast
43 based early action are only beginning to be applied to urban contexts and often those that are most vulnerable
44 do not receive warnings regarding hazardous events (Nissan et al., 2019). There is less capacity for early
45 warning systems in LMICs with key challenges linked to a lack of well-established risk baseline
46 information; accessibility, communication and understanding of forecast information, as well as political and
47 institutional barriers and limited resources and capacities to act on such information (Jones et al., 2015;
48 Mustafa et al., 2015; Zia and Wagner, 2015; Marchezini et al., 2017; Gotgelf, Roggero and Eisenack, 2020).
49 Political and institutional barriers to the incorporation of climate information to decision making are not
50 limited to LMICs (Harvey et al., 2019). For example, comprehensive studies on sectoral use of climate
51 information in Europe revealed that despite climate services becoming increasingly accessible and well
52 resourced, there is limited organizational uptake of seasonal climate forecasts across key sectors (e.g. energy,
53 transport, water and infrastructure) in informing their decision-making processes (Soares and Dessai, 2016;
54 Soares, Alexander and Dessai, 2018). This is due both to technical and non-technical barriers such as lack of
55 awareness and knowledge of climate information and forecasting (Soares and Dessai, 2016; Soares,
56 Alexander and Dessai, 2018).

57

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 1 Globally, a considerable diversity of tools and frameworks for urban resilience assessments being developed
 2 at multiple scales (Arup and Rockefeller, 2015; Elias-Trostmann et al., 2018). These include hybrids such as
 3 Ecosystem based Disaster Risk Reduction (Eco-DRR) (Begum et al., 2014).While important advances have
 4 been made in assessing urban resilience, much debate remains around such tools and assessment approaches
 5 regarding issues such as validation, dynamics in exposure and vulnerability and appropriateness of generic
 6 methods in high density urban settlements (Leitner et al., 2018; Cardoso et al., 2020; Rufat et al., 2019).
 7 Disaster impact and recovery time are strongly influenced by the behaviour and actions of individuals,
 8 communities, businesses, and government organizations (Meriläinen, 2020; Räsänen et al., 2020). For
 9 example, Aaerts et al's (2018) review shows how the limitations of existing flood risk assessment methods
10 (which tend to account for human behaviour in limited terms) can be addressed through innovative flood-risk
11 assessments that integrate behavioural adaptation dynamics. Moghadas et al's (2019) study highlights the
12 importance of hybrid multi-criteria approaches for assessing urban flood resilience in Tehran, Iran. A
13 growing literature shows how multidisciplinary and inclusive approaches that include local knowledges can
14 achieve greater accuracy in risk characterization and support lasting impact of investments into more robust
15 climate services (Aerts et al., 2018; Lourenço et al., 2015; Sword-Daniels et al., 2018; Singh et al., 2018;
16 Nissan et al., 2019; Harvey et al., 2019; Simon and Palmer, 2020). This literature highlights the need for
17 innovative approaches in urban contexts that transcend traditional approaches of local knowledge inclusion
18 widely applied in rural contexts, such as participatory rural appraisal.

19

20 The inclusion of local knowledge and Indigenous knowledge in urban vulnerability and risk assessments can
21 strongly enhance local resilience but its effectiveness is constrained by wider decision-making and policy
22 contexts dominated by top-down approaches (medium evidence; high agreement) (Jones et al., 2015; Sword-
23 Daniels et al., 2018; Nissan et al., 2019). Established non-state actors such as Shack and Slum Dwellers
24 International are particularly effective at implementing inclusive approaches for local knowledge
25 incorporation into urban decision making. Climate change and disaster risk exacerbate existing problems of
26 economic development, yet macro-economic planning seldom incorporates adaptation. Recent evidence also
27 confirms the role of Indigenous knowledge and local knowledge in management practices to reduce climate
28 risks through early warning preparedness and response (see also section 6.3.2.3). These practices are
29 particularly important where alternative early warning methods are absent. For instance, Kasei et al (2019)
30 show that Indigenous knowledge gathered through observations on changes in natural indicators (such as
31 links between rainfall patterns, certain flora and fauna, and temperature changes) could be applied to develop
32 early warning of climate hazards (floods and droughts) in informal urban settlements in African countries
33 like Ghana. Similarly, Hiwaski et al (2015) show that observations of changes in the environment and
34 celestial bodies are used to predict climate-related hazards in Indonesia, the Philippines and Timor-Leste
35 where communities in turn use local materials and methods, and customary practices to respond to the
36 impacts of climate change.

37

38 Insurance is a risk transfer mechanism for middle and high-income countries, yet is less widely available in
39 LMICs (Surminski and Thieken, 2017). Additionally, where insurance options do exist in LMICs, these are
40 not usually available to large populations living or operating in the informal sector. Flood insurance is
41 widely available in many Organisation for Economic Co-operation and Development (OECD) countries but
42 the demand and uptake differ significantly across countries (Hanger et al., 2018). This financial tool is
43 subject to increasing pressure under the changing climate with growing concerns around affordability and
44 availability. More integrative approaches are required, such as where changes in the insurance industry are
45 closely linked to adaptation strategies, building standards and land-use planning and their application
46 (Cremades et al., 2018). This is particularly important in LMICs and of central concern for all insurance
47 schemes is ensuring access, fairness and affordability for the most poor and vulnerable. However, there are
48 some notable examples of low-income communities setting up their own disaster insurance mechanisms. For
49 example, the Community Development Funds for the Baan Mankong upgrading programme in Thailand
50 include disaster funds as insurance against housing damage (Archer, 2012). Such approaches also need to be
51 more closely linked to existing urban risk management planning approaches where urban livelihoods are
52 seldom integrated and informed by more dynamic risk reduction frameworks that consider adaptive cycles
53 and how resilience changes over time (Beringer and Kaewsuk, 2018; Cremades et al., 2018).

54

55 Disaster risk management systems face increasing challenges in adapting to evolving risk profiles, shaped by
56 expanding urban areas and changing environmental conditions associated with climate change. In addition to
57 flooding, risk monitoring and management systems have recently shown considerable shortfalls in planning

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 1 for and responding to increased fire risk such as the devastating Californian wildfires in October 2019
 2 (Morley, 2020) and Australia's unprecedented and catastrophic 2019-2020 wildfire season. Risk
 3 management has also been challenged by new risk experiences including wild/bush fires encroaching on
 4 expanding urban areas and fire outbreaks in densely populated informal settlements pose increasing threats
 5 to livelihoods, human health and habitats globally (see also Sections 2.4.4.2 and 2.5.5.2).

 6

 7 6.3.3.4 Climate Resilient Health Systems

 8

 9 Climate resilient health systems are a vital part of adaptation to protect the most vulnerable from climate
10 change (WHO, 2020). Cardiovascular fitness for example is a root cause of morbidity and mortality form
11 heat stress (Schuster et al., 2017). The World Health Organization has developed a framework of climate-
12 resilient health systems that addresses both mitigation and adaptation goals (WHO, 2015). Universal Health
13 Coverage (UHC) is an essential component of climate resilient health systems. In most countries, access to
14 health services is better in urban than in rural areas. However, there remain large urban populations with
15 insufficient coverage of health services (WHO and WB, 2015) and UHC tracking needs to take better
16 account of inequalities in coverage, including differences in access within cities and further disaggregation
17 of urban populations by income. Thus, health sector investment is an important tool in adaptive action and
18 capacity. Analyses of health survey data shows that, globally, access to health care is increasing towards
19 UHC targets (Lozano et al., 2020). Financing for global health has increased steadily in the last two decades
20 and modelling shows this trend is likely to continue to 2050, but at a slower pace of growth and the current
21 disparities in per-capita health spending persist between high and low/middle income countries, leading to
22 insufficient health service coverage for the poorest populations (Chang et al., 2019a). Out-of-pocket
23 spending is projected to remain substantial in LMIC and will remain the only means to access health care for
24 many poor urban populations.

25

26 The WHO Operational Framework highlights the components that can be strengthened to adapt to extreme
27 weather (e.g., health care workforce, information systems etc.). The evidence is greatest for impacts on
28 larger health facilities (such as hospitals) and there is less evidence regarding impacts on health service
29 delivery outside these settings (smaller health facilities, pharmacies, first responders, public health inspectors
30 etc.). Improved building design and spatial urban planning (where facilities are located) are essential to
31 increase resilience for higher temperature and flood risk (medium evidence; high agreement) (WHO, 2021;
32 Codjoe et al., 2020; Korah and Cobbinah, 2017). Public health systems rely on information systems
33 (including disease and vector surveillance and monitoring) to identify new and emergent public health risks.
34 Improvements to health surveillance will increase resilience, particularly for populations in informal
35 settlements that are absent from health and vital registration systems.

36

37 City-level and local government adaptation planning is facilitated by information on health impacts (Reckien
38 et al., 2015), highlighting the need for monitoring and surveillance and the need for local evidence based risk
39 assessments. Adaptation in the health sector can be limited by lack of collaboration between health and other
40 sectors, although this is often easier to facilitate at the local level (Woodhall, Landeg and Kovats, 2021).

41

42 6.3.3.5 Education and Communication

43

44 Since AR5 there has been significant growth in research about climate education and activism (Simpson,
45 Napawan and Snyder, 2019; O'Brien, Selboe and Hayward, 2018; Hayward, 2021). Access to knowledge is
46 an important determinant of wellbeing, inclusivity and livelihood mobility and of driving human behaviour.
47 Knowledge systems include formal educational provision (capital assets, syllabus and human capital),
48 informal learning based in social interaction and customary institutions (including through social media) and
49 public communication (news media, government and other information systems including commercial
50 messaging). There is a growing body of literature addressing the role of information and communication
51 technology in shaping behaviour in disaster response and recovery and climate action with particular focus
52 on social media use and serious gaming (Houston et al., 2015; Carson et al., 2018) (see Section 6.3.4.3)

53

54 Given the amount of time that children spend in school settings, adapting educational infrastructure and
55 programs to climate change is highly important. This includes not only making physical structures safe but
56 also providing students with the knowledge and confidence to support individual and family-based
57 adaptation. Several UN agencies (e.g. UNICEF and UNDRR) and international non-governmental agencies

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 1 (e.g. Plan International) have prioritised safer schools and child centred risk management that often focus on
 2 schools as places that should be prioritised for retrofitting and safe construction but also as focal points for
 3 knowledge dissemination and community organising where impacts can extend beyond the school to reduce
 4 risk amongst students' families. Universities, think tanks, as well as the third and private sector are key
 5 support mechanisms, particularly at the local level and when working in collaboration with local government
 6 and communities. They can support the development of critical educational resources and innovative
 7 communication methods, as well as facilitate the design and implementation of climate policies and related
 8 action plans.

 9

10 Youth, adult communities, the social media and commercial media can have a significant impact on
11 advancing climate awareness and the legitimacy of adaptive action, particularly in large urban areas (medium
12 evidence; high agreement). Climate change education has increasingly focused in urban settlements on
13 enhancing children and young people's political agency in schools, universities, and in formal and informal
14 media settings (Cutter-Mackenzie and Rousell, 2019). However, an ambiguous framing of climate impacts
15 and adaptation, for example around the science of urban heat islands by media can also exacerbate local
16 community confusion and uncertainty (Iping et al., 2019) and further training and capacity building
17 opportunities such as for vocational qualifications is still required across diverse settings (Simmons, 2021).
18 Communication strategies deployed in formal education and social media can be highly influential in
19 exchanging information and establishing narratives and viewpoints that frame what adaptive action is
20 legitimate, especially in large cities (Simpson, Napawan and Snyder, 2019). However, the effectiveness of
21 communication strategies for change for example from Mayoral offices, can also be influenced by wider
22 political and structural drivers including community literacy or political partisanship (Boussalis, Coan and
23 Holman, 2019). Recent research (e.g. Macintyre et al., 2018) highlights the need for new, learning
24 approaches to climate education from school age to adult education. Emphasis is on inclusivity in learning
25 and recognising diverse perspectives across multiple levels and settings, from formal and informal education
26 to wider social learning. Informal learning that takes place outside of school settings such as in libraries and
27 botanical gardens in everyday life is increasingly recognised as a key arena for climate education, life-long
28 learning and nurturing environmental citizenship and activism (Paraskeva-Hadjichambi et al., 2020).

29

30 6.3.3.6 Cultural heritage/institutions

31

32 The integration of culture into urban policy and planning is increasingly recognised as critical to developing
33 sustainable and resilient cities and features in international agreements such as the SDGs (limited evidence;
34 high agreement) (Sitas, 2020). However, urban cultural policies are still limited, for example, Cape Town is
35 the only African city to have developed a city level cultural policy (Sitas, 2020). Cultural heritage refers to
36 both tangible (e.g. historic buildings and sites) and intangible (e.g. oral traditions and social practices)
37 resources inherited from the past (Fatori and Egberts, 2020; Jackson, Dugmore and Riede, 2018). Learning
38 about past societal and environment changes through heritage offers opportunity for reflection, transfer of
39 knowledge and skills. This takes place in multiple contexts such as museums and cultural landscapes, and in
40 everyday life (Fatori and Egberts, 2020; Jackson, Dugmore and Riede, 2018). Cultural heritage is primarily
41 associated with identity and is closely intertwined with the complexities of history, politics, economics and
42 memory. Climate change adds another layer of complexity to cultural heritage and resource management
43 (Fatori and Seekamp, 2017). Changing climatic conditions are already negatively impacting World Heritage
44 Sites such as the Cordilleras' Rice Terraces of the Philippines and earthen architecture sites - for example the
45 Djenné mosque in Mali are particularly vulnerable to changes in temperature and water interactions
46 (UNESCO, 2021). Climate change impacts intangible cultural heritage across diverse settings such as in the
47 Caribbean and Pacific SIDS where traditional ways of life and related aspects such as oral traditions and
48 performing arts are under threat from extreme weather events (UNESCO, 2021).

49

50 The climate change adaptation options for built cultural heritage fall into seven categories (Rockman et al.,
51 2016; Fatori and Seekamp, 2017). Financial constraints are the primary barriers that underpin the first four
52 adaptation options: no action at all, merely monitoring and/or documenting, or annual maintenance (Xiao et
53 al., 2019; Sesana et al., 2019; Fatoric and Seekamp, 2017; Fatori and Seekamp, 2017; Fatori and Seekamp,
54 2018). Core and shell preservation, the fifth and sixth categories, are cost effective when they improve the
55 condition of built cultural heritage (BCH) (Bertolin and Loli, 2018; Loli and Bertolin, 2018a; Loli and
56 Bertolin, 2018b), while elevation and/or relocation, the final adaptation options, are extremely costly and
57 might jeopardize the historic value (Xiao et al., 2019). To date, however, evidence indicates that adaptation

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 1 actions prioritize archaeological sites (Carmichael et al., 2017; Fatori and Seekamp, 2018; Pollard et al.,
 2 2014; Dawson, 2013). The efficacy of adaptation of historic buildings can be increased through increased
 3 and stable funding, incentives, stakeholder engagement, and legal and political frameworks (Dutra et al.,
 4 2017; Fatori and Seekamp, 2018; Fatori and Seekamp, 2017; Fatoric and Seekamp, 2017; Leijonhufvud,
 5 2016; Phillips, 2015; Sesana et al., 2019; Sesana et al., 2018; Sitas, 2020).

 6

 7 Other barriers to implementation include harnessing expert and local knowledge (of individuals and
 8 organizations) to identify both quantitative and qualitative methods and indicators that connect cultural
 9 significance and local values vis-ŕ-vis climatic change over time and that move beyond the prevalent high
10 risk- or high vulnerability-centred approaches (Carmichael et al., 2017; Fatori and Seekamp, 2018; Haugen
11 et al., 2018; Leijonhufvud, 2016; Pollard et al., 2014; Puente-Rodríguez et al., 2016; Richards et al., 2018;
12 Dawson, 2013; Filipe, Renedo and Marston, 2017; Kotova et al., 2019). This is particularly important given
13 that the significance of cultural heritage is often intangible, and its value cannot be determined solely
14 through quantitative indicators. Accessing local resources (craftsmanship and materials compatible with the
15 originals) can also improve built cultural heritage's adaptation capacity (Phillips, 2015).

16

17 Effective decision making and practice for adapting built and intangible cultural heritage requires open
18 dialogue and exchange of cultural, historical and technical information between diverse stakeholders and
19 decision-makers (Fatori and Seekamp, 2017; Benson, Lorenzoni and Cook, 2016). As noted in Section
20 6.2.6, human behaviour can be a driving force for adaptation impacts on built cultural heritage at risk.
21 Despite challenges associated with intangibility, socio-cultural heritage such as Indigenous knowledge (e.g.
22 food security and water management practices) presents important opportunities for climate adaptation and
23 resilience building. More research is needed across diverse contexts to understand feasible climate adaptation
24 measures and barriers and opportunities for building the resilience of both built and intangible cultural
25 heritage, as well as to increase awareness of cultural heritage benefits among climate change policymakers
26 (Fatori and Egberts, 2020).

27

28 6.3.4 Adaptation Through Nature-Based Solutions

29

30 Well-functioning ecosystems can play a significant role in buffering cities, settlements and infrastructure
31 from climate hazards at multiple scales (robust evidence, high agreement). Nature-based solutions (NBS) are
32 actions to protect, sustainably manage and restore natural or modified ecosystems that address societal
33 challenges effectively and adaptively, simultaneously providing human well-being and biodiversity benefits
34 (Cohen-Shacham et al., 2016). Widely recognized as low-regret measures for disaster risk reduction and
35 climate change adaptation, green and blue infrastructure investments and natural area conservation in cities
36 can provide NBS at across scales to reduce temperature shocks and provide natural flood defences among
37 other adaptation and resilience benefits (McPhearson et al., 2018; Andersson et al., 2019; Frantzeskaki et al.,
38 2019). Blue infrastructure for example provides ecological and hydrological functions (e.g. evaporation,
39 transpiration, drainage, infiltration, detention) critical to sustainable urban water management (Ioj et al.,
40 2021). Public parks, urban forests, street trees and green roofs as well as lakes, ponds and streams are widely
41 documented for providing local cooling, grass and riparian buffers and forested watersheds can enhance
42 flood and drought protection for cities and settlements, and mangrove stands and wetlands in coastal areas
43 can reduce storm surges. Despite increasing knowledge about NBS (here encompassing literature on
44 ecosystem services for climate change adaptation and resilience, ecosystem-based adaptation, and benefits of
45 green and blue infrastructure for adaptation), recent studies indicate that nature-based approaches to
46 adaptation and resilience are still under-recognised and under-invested in urban planning and development
47 (Matthews, Lo and Byrne, 2015; Geneletti and Zardo, 2016; Frantzeskaki et al., 2019), despite the potential
48 scale of benefits ­ for example, a recent study covering 70 cities in Latin America calculated that 96 million
49 people would benefit from improving main watersheds with green infrastructure (Tellman et al., 2018).

50

51 Grey infrastructure often damages or eliminates biophysical processes (e.g. through soil sealing, stream
52 burial, or altered hydrology) necessary to sustain ecosystems and habitats, and livelihoods, where urban
53 ecological infrastructure (Childers et al., 2019) can be more flexible and cost effective for providing flood
54 risk reduction and other benefits (Palmer et al., 2015). Hybrid approaches are emerging that integrate
55 ecological and grey (engineered) infrastructure in adaptation planning and hazard protection (Grimm et al.,
56 2016; Depietri and McPhearson, 2017). Explicit policy uptake by city authorities is increasing (Hansen et al.,
57 2015; Hölscher et al., 2019) such as in New York where in 2010 the city committed to a hybrid infrastructure

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 1 plan for storm water management, investing US$ 5.3 billion over 20 years, of which US$2.4 billion was
 2 targeted for green infrastructure investments (NYC, 2010). A subset of services from urban ecosystems are
 3 being increasingly invested in as NBS for climate adaptation pathways (Keeler et al., 2019; Kabisch et al.,
 4 2016) and included as regulatory drivers through flood management, hazard mitigation, and air pollution
 5 regulations that encourage or enforce the implementation of green infrastructure practices (Davis et al.,
 6 2020).

 7

 8 Development and climate mitigation co-benefits of NBS is an additional reason that NBS are being
 9 increasingly taken up by cities including for improving health and livelihoods, particularly for poor,
10 marginalized groups (Poulsen et al., 2015; Poulsen, Neff and Winch, 2017; Maughan, Laycock Pedersen and
11 Pitt, 2018; Simon-Rojo, 2019; Cederlöf, 2016). Co-benefits include a wide range of social and environmental
12 benefits (Brink et al., 2016; Alves et al., 2019) for human physical and mental health (Kabisch, van den
13 Bosch and Lafortezza, 2017; Sarkar, Webster and Gallacher, 2018; Engemann et al., 2019; Rojas-Rueda et
14 al., 2019), climate mitigation (De la Sota et al., 2019) and as habitat for local biodiversity (Ziter, 2016;
15 Knapp, Schmauck and Zehnsdorf, 2019). At the same time concerns about the unintended consequences of
16 investing in green infrastructure for NBS such as how it may contribute to gentrification (Turkelboom et al.,
17 2018; Anguelovski et al., 2018; Haase et al., 2017b), create more public use, increase water demand (Nouri,
18 Borujeni and Hoekstra, 2019), or contribute to criminal activity (Cilliers and Cilliers, 2015) underlines the
19 challenges of investing in adaptation in complex urban systems (See Section 6.2.6). Additionally, more
20 place-based analysis of the efficacy of nature-based solutions for reducing climate impacts across varying
21 urban contexts and future climate scenarios is needed to better understand the cost effectiveness of investing
22 in NBS to provide disaster risk reduction and deliver critical co-benefits for human well-being. Cooperation
23 between scientists, decision makers and indigenous knowledge-holders can supplement current efforts as
24 well as to ensure that investments in nature-based solutions do not negatively impact indigenous
25 communities (Ban et al., 2018; Seddon et al., 2021; Townsend, Moola and Craig, 2020).

26

27 6.3.4.1 Temperature Regulation

28

29 Nature-based strategies ­ including street trees, green roofs, green walls, and other urban vegetation ­ can
30 reduce heat and extreme heat by cooling private and public spaces (robust evidence, high agreement).
31 Shading and evapotranspiration are the primary mechanisms for vegetation induced urban cooling (Coutts et
32 al., 2016). Shading reduces mean radiant temperature, which is the dominant influence on outdoor human
33 thermal comfort under warm, sunny conditions (Thorsson et al., 2014; Viguié et al., 2020). Outdoor green
34 space and parks may also slightly reduce indoor heat hazard (Viguié et al., 2020). Apart from lowering
35 temperature, nature-based solutions may also contribute to lower energy costs by reducing extra demand for
36 conventional sources of cooling (e.g. air conditioning) (Viguié et al., 2020; Foustalieraki et al., 2017),
37 especially during peak demand periods. Homes with shade trees that are located in cities where air
38 conditioning systems are common can save over 30% of residential peak cooling demand (Zardo et al., 2017;
39 Wang et al., 2015). Green roofs have been shown to significantly lower surface temperatures on buildings
40 (Bevilacqua et al., 2017) and modelling suggests that green roofs, if employed widely throughout urban
41 areas, have the potential to impact the regional heat profile of cities (Bevilacqua et al., 2017; Rosenzweig,
42 Gaffin and Parshall, 2006). Community or allotment gardens, backyard greening, and other types of low
43 vegetation, as well as lakes, ponds, rivers, and streams, can also provide local cooling benefits to nearby
44 residents (Gunawardena, Wells and Kershaw, 2017; Larondelle et al., 2014; Santamouris, 2020).

45

46 Urban climate models show that increased vegetation cover results in reducing both mean air temperatures
47 and extreme temperatures during heat waves (Heaviside, Cai and Vardoulakis, 2015; Ferreira and Duarte,
48 2019; Schubert and Grossman-Clarke, 2013). Greater density and more canopy coverage relative to other
49 built and paved surfaces increases shade provision and evapotranspiration (Hamstead et al., 2016; Grilo et
50 al., 2020; Herath, Halwatura and Jayasinghe, 2018; Knight et al., 2021). However, local cooling by
51 vegetation depends on regional climate context, geographic setting of the city, urban form, the density and
52 placement of the trees, in addition to a variety of other ecological, technical, and social factors, such as local
53 stewardship (Salmond et al., 2016). Green spaces less than 0.5-2.0 ha may have negligible cooling effects at
54 regional scales, but impacts of shading can have microscale cooling benefits (Gunawardena, Wells and
55 Kershaw, 2017; Zardo et al., 2017). Vegetation impacts on day versus night-time cooling varies (Imran et al.,
56 2019) as does cooling potential in temperate versus tropical climates. The supply of cooler air from
57 surrounding peri-urban and rural areas can impact cooling in the urban core suggesting that regional

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 1 adaptation planning for NBS is important to maintain or extend ventilation paths from the urban fringe into
 2 the city centre (Schau-Noppel, Kossmann and Buchholz, 2020).

 3

 4 To maximize the adaptation benefits of NBS for regulating urban heat, it can be helpful to prioritize tree
 5 planting and other urban greening investments in areas where heat vulnerability and risk are the highest,
 6 especially communities that lack urban tree canopy or accessibility to parks to cool off during hot days or
 7 heat waves (Ziter et al., 2019). Planting trees closely together or in partly permeable vegetated barriers along
 8 streets can improve local cooling benefits. Additionally, choosing tree species with leaves that have the
 9 greatest leaf area index or the largest leaves can improve cooling performance, as those trees have the
10 greatest shading and evapotranspiration benefits that, in turn, provide the greatest cooling effects (Keeler et
11 al., 2019). Drought resistant trees, often native trees, are ideal to avoid high watering costs, though dry or
12 water scarce areas may limit adoption of urban vegetation as an NBS strategy (Coutts et al., 2013). Native
13 trees and permaculture can provide additional benefits for local biodiversity as shown in study in Melbourne,
14 Australia which found that increasing vegetation from 10 to 30 percent increased occupancy of bats, birds,
15 bees, beetles and bugs by up to 130% (Threlfall et al., 2017), with particularly high impact on native
16 species.. Additionally, planting fruit or nut trees can provide co-benefits for local food production, and yet
17 choice of species and placement is important to consider with respect to local cultural needs and norms
18 (Adegun, 2018; Adegun, 2017).

19

20 6.3.4.2 Air Quality Regulation

21

22 Nature-based solutions in cities can help regulate air quality by absorbing air pollutants (medium evidence,
23 medium agreement). For example, planting trees or vegetated barriers along streets or in urban forests can
24 reduce particulate matter, the ambient air pollutant with the largest global health burden (Janhäll, 2015;
25 Tiwary, Reff and Colls, 2008; Matos et al., 2019; McDonald et al., 2016). However, findings show that trees
26 can also positively affect ground-level ozone (Calfapietra et al., 2013; Kroeger et al., 2014), airborne pollen
27 concentrations (Willis and Petrokofsky, 2017), and indirectly affect air quality through reduced emissions
28 from energy production offset by shade provision (Keeler et al., 2019). Certain tree species however can also
29 be detrimental to urban ozone formation by emitting significant amounts of reactive biogenic volatile organic
30 compounds (VOCs). Decreasing urban emissions of VOCs is an increasingly important ozone mitigation
31 strategy in urban areas (Fitzky et al., 2019).

32

33 Trees can also have negative effects by increasing pedestrian exposure to pollution if trees are introduced in
34 heavily travelled street canyons where air pollutants can be trapped (Vos et al., 2013; Gromke and Blocken,
35 2015). To maximize the adaptation benefits of NBS for improving air quality planners and managers can
36 target tree selection for species with low VOC emissions, low allergen emissions, and high pollutant
37 deposition potential (Keeler et al., 2019) and combine with low pollution transportation policies. Studies
38 suggest sensitive planting of roadside tree canopies can have positive effects on air pollutants (Beckett, Freer
39 Smith and Taylor, 2000; Yang, Chang and Yan, 2015). For example, Xue et al (2021) found that the PM2.5
40 reduction between 2013 and 2017 in China was associated with a saving of approximately USD 111 billion
41 per year nationally. Tree planting near schools, nursing homes, and hospitals can ensure that benefits
42 provided by trees are delivered to the local populations that stand to benefit the most from improved air
43 quality, but species need to be adapted to regional climate to provide benefits over time (Donovan, 2017;
44 Nowak et al., 2018).

45

46 6.3.4.3 Stormwater Regulation and Sanitation

47

48 Urban parks and open spaces, forests, wetlands, green roofs and engineered stormwater treatment devices
49 help manage stormwater and wastewater by reducing the volume of stormwater runoff, reducing surface
50 flooding, and reducing contamination of runoff by pollutants (robust evidence, high agreement). Engineered
51 devices include bioswales, rain gardens, and detention and retention ponds, and are becoming common and
52 standard approaches to mitigate the negative effects of impervious surfaces on stormwater quality and
53 surface flooding in cities (Zhou, 2014; McPhillips et al., 2020). Allotment gardens, street trees, green roofs
54 and urban forests may also help reduce runoff and provide a stormwater retention service (Pennino,
55 McDonald and Jaffe, 2016; Berland et al., 2017; Gittleman et al., 2017). Modelling and empirical studies
56 show that nature-based solutions at small spatial scales lead to improvements in water quality and reduction
57 of peak flows (Moore et al., 2016; Keeler et al., 2019; Webber et al., 2020). Peak flow reductions are greatest

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 1 for small rain events. For example, D-Ville et al. (2018) observed 30-70% reduction in peak flow for the 1 in
 2 30 year storm, but performance reduces for more intense rainfall or if saturated (Garofalo et al., 2016).
 3 Employing NBS to reduce flooding on roads can be an important adaptation mechanism for reducing the
 4 impact of flooding events on traffic flows (Pregnolato et al., 2016).

 5

 6 During periods with intense precipitation, low-lying urban parks and open space, engineered devices, and
 7 wetlands can play an important role in reducing stormwater runoff volumes, by providing places for water to
 8 be stored and infiltrate during heavy storms (Moore et al., 2016). However, the magnitude of the runoff
 9 reduction service will depend on the total area of green infrastructure, vegetation type, and its position on the
10 landscape. There is less evidence of the effectiveness of nature-based solutions at larger temporal and spatial
11 scales (Pregnolato et al., 2017; Jefferson et al., 2017). The performance of NBS depends on the degree to
12 which their extent and spatial configuration in the city are optimized to capture runoff (Fry and Maxwell,
13 2017). Investing in a diversity of NBS types may be important to maximize stormwater management and
14 flood regulation as different types of engineered NBS have different strengths and weaknesses.

15

16 Overall, NBS are attractive adaptation options for stormwater management and to reduce impacts of pluvial
17 and fluvial flooding in cities (Rosenzweig et al., 2018a) compared to, and in combination with, grey
18 infrastructure. Cities with combined sewer infrastructure are likely to see benefits from NBS due to
19 reductions in stormwater quantity and reduced sewage overflows. Cities where a large proportion of
20 residents lack access to piped infrastructure and drink surface water may see large benefits, especially to
21 human health, from NBS investments (Keeler et al., 2019). Where future large-scale upgrades or installation
22 of grey infrastructure will be necessary, new and growing cities may have more opportunity to realize large
23 net benefits from investments in NBS. Older cities, and new, rapidly urbanizing areas that lack large scale
24 water infrastructure may see the greatest benefits from enhanced NBS, relative to cities where heavy
25 investments infrastructure upgrades have already been made. Cities facing climate changes that including
26 more frequent or extreme precipitation may also see large water quality benefits from investment in NBS
27 (Keeler et al., 2019). Overall, there is increasing evidence that NBS for addressing stormwater is cost-
28 effective (Bixler et al., 2020; Kozak et al., 2020; Mguni, Herslund and Jensen, 2016), especially in cities
29 facing a need to update current infrastructures.

30

31 6.3.4.4 Coastal Flood Protection

32

33 Coastal ecosystems including coral and oyster reefs, coastal forests including mangroves and other tree
34 species, salt marshes and other types of wetland habitat, seagrass, dunes, and barrier islands can reduce
35 impacts of coastal flooding and storms (robust evidence, high agreement) (Zhao, Roberts and Ludy, 2014;
36 Boutwell and Westra, 2016; Narayan et al., 2017; Yang, Kerger and Nepf, 2015; Bridges et al., 2015; World
37 Bank, 2016) (see also CCP2 Cities and Settlements by the Sea). Recent literature highlights the value of
38 nature-based approaches for coastal protection in terms of avoided damages and human well- being (Narayan
39 et al., 2017; Silva et al., 2016a). Nature-based solutions (NBS) can protect coasts from flooding through
40 reducing the wave energy by drag friction, reducing wave overtopping by eliminating vertical barriers, and
41 absorbing floodwaters in soil (Arkema, Scyphers and Shepard, 2017; Dasgupta et al., 2019; Zhu et al., 2020).
42 For example, coastal and marine vegetation and reefs can dissipate wave energy, attenuate wave heights and
43 nearshore currents, decrease the extent of wave runup on beaches, and trap sediments (Ferrario et al., 2014;
44 Bridges et al., 2015). These effects result in lower water levels and reduce shoreline erosion, which in turn
45 has potential to save lives and prevent expensive property damages (Narayan et al., 2017).

46

47 Researchers, practitioners, and policy-makers are increasingly calling for the use of nature-based approaches
48 to protect urban shorelines from coastal hazards (Cunniff and Schwartz, 2015; Bilkovic et al., 2017). The
49 expectation is that coastal ecosystems can help stabilize shorelines, protect communities against storm surge,
50 and from tidal influenced flooding while providing other co-benefits for people and ecosystems. However,
51 vegetation along protected coastlines, with higher frequency, lower intensity coastal hazards (National
52 Research Council, 2014) may be more effective for stabilizing shorelines and reducing risk to coastal
53 communities and properties and benefits will depend on local hydrology of the coastal region. Narayan et al.
54 (2017) estimate that coastal wetlands alone reduced direct flood damages by US$625 million during
55 Hurricane Sandy in the United States in 2012. Similarly, researchers found that villages with wider
56 mangroves between them and the coast experienced significantly fewer deaths than villages with narrow or
57 no mangroves during a 1999 cyclone in India (World Bank, 2016). Recently, Arkema et al. (2017) noted that

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 1 the number of people, poor families, elderly and total value of residential property most exposed to hazards
 2 along the entire coast of the USA can be reduced by half if existing coastal habitats remain fully intact.

 3

 4 Coastal habitats also have limitations in their ability to protect coasts from extreme events. Some studies
 5 suggest reduced effectiveness of vegetation and reefs for coastal protection from large storm waves and
 6 surge (Möller et al., 2014; Guannel et al., 2016) and there is active debate in the literature about the ability of
 7 ecosystems to mitigate the impact of tsunamis (Gillis et al., 2017). Further research is needed to understand
 8 and quantify coastal protection services provided by these hybrid green-grey solutions, especially in urban
 9 areas (Bilkovic et al., 2017). Additionally, in some coastlines water may be too deep or waves too high for
10 some species such as mangroves to grow, thrive and provided needed NBS.

11

12 Maximizing the adaptation benefits of NBS for improving coastal flood protection research requires that
13 cities seek to restore and conserve the vegetation and reef types that are appropriate for the exposure setting
14 and in sufficient abundance to be effective. In particular planners and managers can use vegetation in
15 protected bays as alternatives to hard infrastructure for shoreline stabilization. However, the influence of
16 ecosystems on flooding and erosion is variable and depends on a suite of social, ecological, and
17 infrastructural factors that vary within and among urban areas (Narayan et al., 2017; Ruckelshaus et al.,
18 2016; Bridges et al., 2015). Additionally, long-term planning to restore or ensure resilience of individual
19 species and ecosystems that may themselves be damaged or destroyed during extreme events is needed in
20 order for urban green and blue infrastructure to continue providing NBS over the longer term.

21

22 6.3.4.5 Riverine Flood Impact Reduction

23

24 Nature-based solutions reduce both the volume of floodwater and the impact of floods (medium evidence,
25 medium agreement). NBS reduce the volume of runoff by increasing infiltration and water storage (Shuster
26 et al., 2005; Salvadore, Bronders and Batelaan, 2015), and affect the production and impact of flood waters
27 through reducing river energy and flow speed through physical blockage, stabilizing riverbanks during flood
28 events, creating space for floodwaters to expand, and combating land subsidence (Palmer, Filoso and Fanelli,
29 2014; Ahilan et al., 2018). Installing nature-based solutions to increase infiltration on low slopes and high-
30 permeability soils can reduce the impacts of potential increases in urban flooding driven by climate change,
31 especially for small to medium-scale flood events (lower than 20% mean annual flood) (Moftakhari et al.,
32 2018).

33

34 Source reduction strategies include creating permeable areas such as parks and open spaces as well as
35 engineered devices like raingardens, bioswales, and retention ponds that help retain stormwater runoff from
36 impervious areas. River restoration can reduce flood peak flow and provide space for floodwaters to expand.
37 Planting and maintaining vegetation along riverbanks, often in the form of parks or river restoration,
38 maintains structural integrity during flood events. Wetland construction and improved connectivity to
39 floodplains also reduces flood peaks. Efforts to restore floodplains are important to create space for
40 floodwaters and reduce exposure by moving people out of the hazard zone. Floodplain restoration also
41 provides access to the river that has multiple benefits including recreation, access to water for domestic use,
42 and other cultural ecosystem services. A key adaptation strategy is to reduce streambank erosion (a result of
43 high peak flow) using riparian vegetation to stabilize riverbanks during flood events.

44

45 Cities manage flood risk using different types of adaptation and regulatory mechanisms (Naturally Resilient
46 Communities, 2017). Built flood-control infrastructure, such as levees and stream channelization, reduces the
47 demand for nature-based flood impact reduction. Cities facing flood risk that do not currently have extensive
48 grey flood-mitigation infrastructure may find nature-based solutions to be an appealing, lower cost solution
49 (Keeler et al., 2019). In cities where flood-control grey infrastructure already exists there is less demand for
50 nature-based solutions of flood protection, but nature-based solutions may provide important back-up,
51 especially in a changing climate that may increase flood hazards (City of Los Angeles, 2017; Elmqvist et al.,
52 2019). Overall, city and basin wide NBS for riverine flood impact reduction can reduce the generation of
53 new hazards by making space for water which can reduce the potential for a false sense of security provided
54 by traditional flood management approaches (Ruangpan et al., 2020; Turkelboom et al., 2021).

55

56 6.3.4.6 Water Provisioning and Management

57

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 1 The role of nature-based solutions has been increasingly recognized for improving urban water management
 2 emphasizing it contribution for climate adapted development and sustainable urbanization (robust evidence,
 3 high agreement) (Wong and Brown, 2009). Nature-based solutions that protect or restore the natural
 4 infiltration capacity of a watershed can increase the water supply service to various extents, improving
 5 drought protection, and provide resilient water supply (Drosou et al., 2019; Krauze and Wagner, 2019),
 6 although different forms of NBS (e.g. street trees, parks and open space, community gardens, and engineered
 7 devices such as rain gardens, bioswales or retention ponds) contribute in different ways to increasing
 8 stormwater infiltration. Additional sources of water may be available to replace the water supplied by nature-
 9 based solutions, such as rainwater harvesting, inter-basin transfers, or desalination plants. Reliance on
10 naturally sourced, locally available surface water and groundwater is more energy-efficient and economical
11 than desalination or water reuse for potable use (Boelee et al., 2017), while rainwater harvesting is even
12 more economical. Increasing the amount of green space in urban areas can secure and regulate water
13 supplies, improving water security (Liu and Jensen, 2018; Bichai and Cabrera Flamini, 2018). However,
14 Bhaskar et al (2016) reviewed the effect of urbanization and nature-based solutions on baseflow and suggest
15 that the confounded effects of infiltration and evapotranspiration losses, combined with the subsurface
16 infrastructure (sewer systems) and geology, makes it difficult to predict the magnitude of baseflow
17 enhancement resulting from the implementation of nature-based solutions in cities.

18

19 To maximize the adaptation benefits of NBS for urban water supply research suggests that managers and
20 planners consider nature-based solutions as alternatives to traditional stormwater management techniques,
21 where possible, since these solutions can promote groundwater recharge. As green infrastructure is
22 increasingly being used for stormwater absorption in cities (McPhillips et al., 2020), rain gardens, wetlands,
23 or engineered infiltration ponds and bioswales are the nature-based solutions most likely to promote
24 recharge, reduce evapotranspiration, and contribute to water provisioning.

25

26 6.3.4.7 Food Production and Security

27

28 Urban agriculture can serve as a NBS for food security (medium evidence, medium agreement) across a
29 range of urban contexts (Lwasa and Dubbeling, 2015; Nogeire-McRae et al., 2018; Pourias, Aubry and
30 Duchemin, 2016) by contributing to food provisioning as well as providing co-benefits including for
31 recreation, place-making, and mental health (Petrovic et al., 2019; Soga, Gaston and Yamaura, 2017;
32 Goldstein et al., 2016b).

33

34 Urban agriculture among poorer communities in lower income areas is already an important source of food
35 supply for those communities contributing to food security and health (Orsini et al., 2013). However,
36 potential for expanding open air urban food production may be practically constrained by land availability
37 (Badami and Ramankutty, 2015; Martellozzo et al., 2014). This is particularly true in some lower-income
38 countries where rapid urbanization is occurring, which compounds existing food insecurity (Satterthwaite,
39 McGranahan and Tacoli, 2010; Vermeiren et al., 2013). Land availability and suitability for gardens can be
40 further constrained by land-use history, including past industrial uses that can contaminate soils with
41 pollutants such as lead.

42

43 At the same time, investments in vertical agriculture continue to expand, such as in Singapore where private
44 investment in food production is occurring in high rise buildings (Wong, Wood and Paturi, 2020). Not all
45 cities can benefit similarly from vertical agriculture since higher heating costs to produce vegetables indoors
46 during northern winters consumes considerable amounts of energy and may generate fossil fuel emissions
47 depending on the energy source (Goldstein et al., 2016a; Mohareb et al., 2017). Some regions can benefit
48 from more traditional outdoor urban farming such as in South and Southeast Asia which can support multiple
49 growing cycles per year for some crops, particularly in tropical areas where irrigation is available. Light
50 availability, soil health, and water available will impact food production in urban areas. For example, a study
51 conducted in Vancouver, Canada, demonstrated that light attenuation from buildings and trees can both
52 reduce crop yield and reduce water demand for crop growth (Johnson et al., 2015).

53

54 Climate change may have important impacts on urban food production and food security. While urban
55 agriculture may provide benefits in terms of stability of food access in low-income households in some
56 regions of the Global South where the climate is warmer, the shorter growing seasons in colder climates will
57 reduce the role of outdoor urban agriculture in year-round food supply and diets. Though urban agriculture

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 1 constitutes a small fraction of total food consumption in some urban areas, several studies have attempted to
 2 estimate the extent to which urban agriculture could theoretically meet urban total food or vegetable demand
 3 (Badami and Ramankutty, 2015; McClintock, 2014; Hara et al., 2018). Maximizing the adaptation and
 4 resilience benefits of NBS for food production and security suggests the need to embrace the multi-
 5 functionality of urban agriculture rather than viewing it as solely concerning food production (Barthel,
 6 Parker and Ernstson, 2015).

 7

 8 6.3.5 Adaptation Through Grey/Physical Infrastructure

 9

10 Globally it is estimated that as much as US$94tn of investment is required between 2016 and 2040 to
11 replace, upgrade and extend the world's physical infrastructure (Oxford Economics, 2017), much of which is
12 ageing and will require replacement. Given the typical lifespan of infrastructure this is both an opportunity
13 and an imperative to ensure this investment is low carbon and resilient to climate change risks (Grafakos et
14 al., 2020). `Grey' or physical infrastructure is a priority for adaptation because its performance is sensitive to
15 climate (particularly extreme events) and decisions on design and renovation have long-lasting implications
16 and are hard to reverse (Ürge-Vorsatz et al., 2018). Avoiding longer-term impacts on society, the economy,
17 and environment, will require future investment, and retrofit of existing infrastructure, to be undertaken in
18 the context of the risks of climate change (Dawson et al., 2018; Rosenzweig et al., 2018b). However,
19 evidence from Africa shows that the benefits of pro-active adaptation measures and policies for
20 infrastructure can result in net savings depending on the country context (Section 9.8.5).

21

22 Engineered measures for hazard mitigation such as seawalls, slope revetments, river levees, as well as air
23 conditioning are increasingly implemented in urban centres but many engineering interventions are less
24 affordable and accessible in low and middle-income countries due to high construction and maintenance
25 costs. These adaptive measures can also counter mitigation objectives due to reliance on climate polluting
26 energy sources. Despite this, engineering measures such as seawalls for tsunami protection and cooling areas
27 in cities provide critical hazard reduction functions in urban contexts (Depietri and McPhearson, 2017). As
28 Pelling et al (2018a) highlight, sustainable risk reduction can be better achieved where these engineering
29 measures include the at-risk poor majority and inclusive planning to support pro-poor risk reduction.
30 Inclusive design and management of physical infrastructure can enhance contributions to Climate Resilient
31 Development (Table 6.6 and Supplementary Material). This section covers urban morphology and built
32 form, building design, information and communication technology, energy, transport, water and sanitation,
33 and coastal management. All these domains of physical infrastructure will require adaptation to cope with a
34 changing climate, many of them can also contribute to broader adaptation for cities and settlements.

35

36 6.3.5.1 Urban Morphology and Built Form

37

38 Urban morphology describes the overall status of cities as physical, environmental and cultural entities.
39 Cities interact with surrounding environmental processes ­ for example as documented in Section 6.2 by
40 influencing urban temperature, but also precipitation and through coastal and riverine development fluvial
41 and coastal sedimentary regimes of erosion and deposition that impact on flood risk. Rapid, increased
42 urbanization has contributed to observed flood risks in recent decades (see Chapter 5 4.2.4 (Tramblay et al.,
43 2019)). The design process for physical infrastructure projects and significant construction (e.g. residential or
44 industrial estates and large industrial development) typically includes risk assessments and social and
45 environmental impact assessments that consider neighbouring land uses and connected infrastructure. Land
46 use planning can consider diverse land-uses and their interactions at the neighbourhood level (Section
47 6.3.2.1). Resilience planning aims to bring together integrated, systemic views and enable joined-up planning
48 at the city level (as well as lower scales) (Section 6.3.2.1). There is however a lack of long-term studies that
49 assess the climate change impacts on urban form, including informal settlements (Bai et al., 2018; Ramyar,
50 Zarghami and Bryant, 2019), leading to impact assessments that often overlook urban form (Ramyar,
51 Zarghami and Bryant, 2019). Additionally, context-specific spatial tools and community-based approaches
52 lack a precise connection to urban morphology. For example, there is a need for further studies that connect
53 solar radiation, urban morphology (e.g., aspect and plot ratio), and the urban heat island spatio-temporal
54 variability (Giridharan and Emmanuel, 2018; Li et al., 2019c).

55

56 Several tools and models have emerged in response to recommendations from AR5, including models that
57 assess the impacts of urban heat island (Ramyar, Zarghami and Bryant, 2019), climatic uncertainty (Dhar

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 1 and Khirfan, 2017), flood vulnerability (Abebe, Kabir and Tesfamariam, 2018), and inundation (Barau et al.,
 2 2015; Ford et al., 2019). For example, findings from Kano, Nigeria reveal that a lack of distribution of
 3 certain urban morphological features, including open spaces and streets (both pervious and impervious), roof
 4 and building materials (e.g., concrete and metallic), and urban ecological features (e.g., urban ponds and
 5 ecological basin) exacerbates inundations and their associated impacts (Barau et al., 2015). Also, findings
 6 about the urban forms of coastal settlements, particularly in small islands, reveal that they often experience
 7 severe beach erosion due to wave action, sea-level rise and storm surge that leads to landward retreat of
 8 coastline which threatens their social and economic activities (Dhar and Khirfan, 2016; Lane et al., 2015;
 9 Khirfan and El-Shayeb, 2019). Despite these examples very limited research is available to offer assessments
10 of different urban scale morphologies and urban scale adaptation planning, including planning adaptation
11 across supply chains and networked relationships with distant urban and rural places connected through trade
12 and resource (financial, human and material) or waste flows.

13

14 Interventions in the morphology and built form of cities can contribute to the reduction of the urban heat
15 island effect and reduce the consequences of urban heat waves. These can include installing air conditioning,
16 establishing public cooling centers (i.e., for use during heat waves), pavement-watering (Parison et al.,
17 2020a), and increasing surface albedo through "cool roofs" (i.e., with high-reflectance materials) and walls.
18 Air conditioning can significantly increase the local urban heat island (Salamanca et al., 2014; Wang et al.,
19 2019a) and the choice of refrigerant has a significant impact on global warming potential (McLinden et al.,
20 2017). The relative efficiency of cool roofs compared to green roofs is variable, because while white roofs
21 have similar potential to reduce the urban heat island (Li, Bou-Zeid and Oppenheimer, 2014), they can
22 quickly turn grey due to dust and air pollution, losing their effectiveness (Gunawardena, Wells and Kershaw,
23 2017) although these effects are now well studied and newer performance standards should account for
24 ageing and soiling effects on reflectivity (Paolini et al., 2014). Ageing of "cool pavements" is more complex
25 which makes their long term performance less reliable to predict (Lontorfos, Efthymiou and Santamouris,
26 2018). The cooling performance of green roofs is highly variable and depends on the actual water content of
27 the green roof substrate, with dry vegetation performing poorly in terms of cooling (Parison et al., 2020b).
28 This holds true for regular vegetation and Nature-Based Solutions in general (Daniel, Lemonsu and Viguie,
29 2018). For all built environment adaptations, changes are locked-in for a long time and are likely to be
30 expensive so that care is needed to avoid potential negative impacts on social equity (Cabrera and Najarian,
31 2015; Romero-Lankao et al., 2018; Fried et al., 2020; Rode et al., 2017) and carbon-intensive construction
32 (Bai et al., 2018; Seto et al., 2016).

33

34 6.3.5.2 Building Design and Construction

35

36 Architectural and urban design regulations at the single building scale (building codes and guidelines)
37 facilitate climate responsive buildings that adapt to a changing climate and have the potential to collectively
38 change user behaviour during extreme weather events (Osman and Sevinc, 2019). They include buildings
39 that are adaptive to ensure user comfort during extremes of hot and cold, and to floods (e.g., building on
40 stilts and amphibian architecture). Changes to design standards can scale quickly and widely, but retrofit of
41 existing buildings is expensive so care must be taken to avoid potential negative impacts on social equity
42 (Schünemann et al., 2020; Matopoulos, Kovács and Hayes, 2014; Ajibade and McBean, 2014; Bastidas-
43 Arteaga and Stewart, 2019). Buildings can be adapted to the negative consequences of climate change by
44 altering their characteristics, for example increasing the insulation values (e.g. van Hooff et al., 2014;
45 Makantasi and Mavrogianni, 2016; Fisk, 2015; Fosas et al., 2018; Barbosa, Vicente and Santos, 2015;
46 Invidiata and Ghisi, 2016; Pérez-Andreu et al., 2018; Taylor et al., 2018; Triana, Lamberts and Sassi, 2018),
47 adding solar shading (e.g. van Hooff et al., 2014; Makantasi and Mavrogianni, 2016; Barbosa, Vicente and
48 Santos, 2015; Invidiata and Ghisi, 2016; Pérez-Andreu et al., 2018; Taylor et al., 2018; Triana, Lamberts and
49 Sassi, 2018; Dodoo and Gustavsson, 2016; Osman and Sevinc, 2019), increasing natural ventilation,
50 preferably during the night (e.g. van Hooff et al., 2014; Makantasi and Mavrogianni, 2016; Pérez-Andreu et
51 al., 2018; Triana, Lamberts and Sassi, 2018; Dodoo and Gustavsson, 2016; Osman and Sevinc, 2019;
52 Mulville and Stravoravdis, 2016; Cellura et al., 2017; Fosas et al., 2018; Dino and Meral Akgül, 2019), solar
53 orientation of bedroom windows (Schuster et al., 2017), applying high-albedo materials for the building
54 envelope (van Hooff et al., 2014; Invidiata and Ghisi, 2016; Baniassadi et al., 2018; Triana, Lamberts and
55 Sassi, 2018), altering the thermal mass (van Hooff et al., 2014; Mulville and Stravoravdis, 2016; Din and
56 Brotas, 2017), adding green roofs/facades to poorly insulated buildings (Geneletti and Zardo, 2016;

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 1 Skelhorn, Lindley and Levermore, 2014; van Hooff et al., 2014; de Munck et al., 2018; Feitosa and
 2 Wilkinson, 2018) and for water harvesting (Sepehri et al., 2018).

 3

 4 In general, the most promising adaptation measures are a combination of solar shading with increased levels
 5 of insulation and ample possibilities to apply natural ventilation to cool down a building (e.g. van Hooff et
 6 al., 2014; Makantasi and Mavrogianni, 2016; Fosas et al., 2018; Barbosa, Vicente and Santos, 2015; Taylor
 7 et al., 2018; Triana, Lamberts and Sassi, 2018; Dodoo and Gustavsson, 2016). However, it must be noted
 8 that the cooling potential of natural ventilation will decrease in the future due to increasing outdoor air
 9 temperatures (Gilani and O'Brien, 2020). Increased insulation (including through green solutions) without
10 shading and ventilation can also lead to adverse impacts through the lowering of night-time cooling (Reder et
11 al., 2018). Similarly, air conditioning performance also decreases with increasing outdoor temperatures, in
12 addition to being maladaptive where use increases anthropogenic heat emissions into the urban area, and
13 global greenhouse gas emissions if powered by carbon intensive energy systems (Wang et al., 2018c).

14

15 Passive cooling is a design-based, widely used strategy to create naturally ventilated buildings, making it an
16 important alternative to address the urban heat island for residential and commercial buildings (Al-Obaidi,
17 Ismail and Rahman, 2014). Generally, passive cooling is achieved by controlling the interactions between
18 the building envelope and the natural elements. Façade fixes such as overhangs, louvres, and insulated walls
19 are effective at shading buildings from solar radiation while complex ones such as texture walls, diode roofs,
20 and roof ponds are effective at minimizing heat gains from solar radiation and ambient heat (Oropeza-Perez
21 and Řstergaard, 2018). Passive cooling is inspired also by traditional design forms, for example from
22 Mediterranean, Islamic and Mughal architecture in the Indian sub-continent (Di Turi and Ruggiero, 2017;
23 Izadpanahi, Farahani and Nikpey, 2021).

24

25 In addition, wind towers, solar chimneys, and air vents are features that facilitate cool air circulation within
26 buildings while dissipating heat (Bhamare, Rathod and Banerjee, 2019). These features may be arranged to
27 address hotspots or highly frequented spaces within buildings. Similar to nature-based solutions, the
28 effectiveness of passive cooling to ameliorate the urban heat island varies widely depending on the location
29 of the sun, wind direction, and the type of strategy used. For instance, natural ventilation strategies (e.g. wind
30 towers, solar chimneys, etc.) have shown temperature reductions of up to 14°C (Bhamare, Rathod and
31 Banerjee, 2019; Calautit and Hughes, 2016; Rabani et al., 2014). Shading strategies alone can reduce indoor
32 temperatures by 3°C, while heat sinks (in which heat is directed at a medium such as water) may result in
33 indoor temperatures up to 6 °C lower than the outdoor temperature (Oropeza-Perez and Řstergaard, 2018).
34 More systemic interventions, such as altering urban form through urban planning can mitigate the urban heat
35 island across suburbs and cities (Lee and Levermore, 2019; Takkanon and Chantarangul, 2019; Yin et al.,
36 2018; Liang and Keener, 2015; Emmanuel and Steemers, 2018). Experience in Kano (Nigeria) has shown
37 that incorporating Indigenous knowledge into building design and urban planning can increase resilience to
38 heat and flood risks (Barau et al., 2015). A review by Lemi (2019) suggests that traditional ecological
39 knowledge can provide wider climate change adaptation benefits.

40

41 Limits on housing and building adaptation include failure of regulatory systems so that formal design
42 standards are not followed even when legally required (Arku et al., 2016; Durst and Wegmann, 2017; Pan
43 and Garmston, 2012; Awuah and Hammond, 2014). This can be a result of pressures from clients for cheaper
44 structures, developers illegally cutting costs or regulators lacking capacity for enforcement. Technological
45 innovation can also be slow to embed itself in building norms and standards. Innovation also lies outside the
46 formal sector and can include artisanal building techniques that may have adaptive value. Examples from
47 Latin America demonstrate how initiatives in informal settlement improvement associated with housing
48 policy, guaranteeing access to land and decent housing, show the opportunity for overarching policies
49 encompassing development, poverty reduction, disaster-risk reduction, climate-change adaptation, and
50 climate-change mitigation (See 12.5.5).

51

52 6.3.5.3 Information and Communication Technology

53

54 Information and Communication Technologies (ICTs) are deeply intertwined with the functioning of urban
55 and infrastructure systems, and are at the core of the `smart city' concept (Angelidou, 2015). ICT is more
56 flexible than other physical infrastructure, although as other sectors are increasingly reliant on ICT it is
57 creating new climate-related failure mechanisms (Norman, 2018; Maki et al., 2019). ICT assets and networks

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 1 in urban, national and international communications systems will need to be strengthened to enable ICT
 2 infrastructure to better cope with climate change, and to enable ICT infrastructure to support the resilience of
 3 cities, settlements, and other infrastructure. The increased pervasiveness of ICT, in smart cities, smart
 4 infrastructure and day to day living, will evidently have long term implications for exposure to climate
 5 change risks and how cities manage those risks (Norman, 2018; Maki et al., 2019). For example, even if the
 6 ICT network is resilient to heatwaves, it is dependent on the electricity network to power it. Conversely,
 7 other networks are dependent upon ICT for control systems, e.g., Smart Grids for energy. There is limited
 8 information on how these interdependencies, and associated risks, will evolve.

 9

10 Although networked like many other infrastructure systems, ICT components have some distinctive
11 properties. They are relatively cheap, and the advent of wireless communications has enabled ICT to have
12 the widest reach of all infrastructures. Components can be rapidly deployed or repaired, and generally ICT
13 networks are therefore built with inherent redundancy and flexibility (Sakano et al., 2016). Components have
14 a wide range of expected lifetimes which leads to faster cycles of innovation. There is therefore greater
15 potential to accelerate uptake of climate resilience in this infrastructure sector, but conversely this can
16 increase waste and (energy intensive) resource consumption. For example, mobile phones and computers
17 may last as little as a year, cables and switching units may be moved and upgraded to improve bandwidth
18 every few years, poles and masts are typically designed to last several decades, whilst exchanges and other
19 critical nodes can be in use for over half a century.

20

21 ICTs are playing an increasing role in resilience building and enabling climate change adaptation. They are
22 enabling access to information needed for decision-making, facilitating learning and coordination among
23 stakeholders and building social capital, as well as helping to monitor, visualize and disseminate current and
24 future climate impacts (Eakin et al., 2015; Heeks and Ospina, 2019; Haworth et al., 2018; Imam, Hossain
25 and Saha, 2017). Advocacy and awareness raising through ICTs such social media applications can influence
26 behaviours and attitudes in support of adaptive pathways (Laspidou, 2014).

27

28 ICTs play a role in adaptive responses to both short-term shocks and long-term trends associated with
29 climate change. Timely access to information (e.g. early warning, temperature and rainfall, agricultural
30 advice) through ICTs (e.g. mobile devices, SMS, radio, social media) can be crucial to respond and mitigate
31 the impact of emergencies such as floods and drought, for identifying pest and disease prevalence, and for
32 informing livelihood options, key in adaptation pathways of vulnerable (Devkota and Phuyal, 2018; Panda et
33 al., 2019).

34

35 In addition to contributing to the robustness and stability of the critical infrastructure in the event of
36 disasters, ICTs can strengthen other attributes of resilient urban systems by enabling learning and community
37 self-organization, cross-scale networks and flexibility, helping vulnerable stakeholders, in particular, to
38 adjust to change and uncertainty (Heeks and Ospina, 2015; Heeks and Ospina, 2019). Big data is being used
39 to inform responses to humanitarian emergencies (Pham et al., 2014; Ali et al., 2016), as well as to generate
40 new forms of citizen engagement and reporting (e.g. community-based maps of flood-prone areas) that can
41 help to inform coping and adaptive responses (Ogie et al., 2019).

42

43 The selection and use of ICTs for adaptation needs to be fairly grounded in the broader socio-cultural,
44 economic, political and institutional context, to ensure that these tools effectively help address existing,
45 emerging and future adaptive needs. Typically, ICT is inadequate on its own to make a significant difference
46 (Toya and Skidmore, 2015). The role of ICTs in adaptive pathways is influenced by; the availability of
47 locally relevant information (e.g. weather-based advisory messages, local market prices), the accessibility of
48 information by all members of the community (e.g. using various text, audio and visual content, local
49 languages, addressing gender-related exclusion, cost and digital competencies), and the applicability of
50 information at the appropriate scale (local, regional or national), including data quality and verification
51 (Namukombo, 2016; Haworth et al., 2018).

52

53 Information privacy and security, as well as the unintended impacts of ICTs on inequality, spread of
54 misinformation, and on widening existing gaps (e.g. due to poverty, gender and power differentials), can also
55 constrain the contribution of ICTs to urban adaptation (Haworth et al., 2018; Coletta and Kitchin, 2017;
56 Leszczynski, 2016) and are among the key challenges that need to be addressed in order to fully realize their
57 potential.

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 1

 2 6.3.5.4 Energy

 3

 4 A number of measures are available to adapt existing energy infrastructure to climate change. These
 5 typically involve changing engineering design codes and upgrading facilities to cope with new climatic
 6 conditions, building redundancy and robustness into systems, and preparation to ensure continued operation
 7 following extreme events. Adapting low carbon energy infrastructure improves its climate resilience whilst
 8 simultaneously delivering mitigation goals (Kemp, 2017; Feldpausch-Parker et al., 2018), benefitting all
 9 other sectors (Dawson et al., 2018; Pescaroli and Alexander, 2018; Kong, Simonovic and Zhang, 2019).

10

11 Hall et al. (2019) identified 4223GW of global power generation at risk of flooding. If these assets were
12 protected by 0.5m flood protection, ~700GW would be at risk from the 1 in 100-year flood. Many assets can
13 be strengthened, relocated, or replaced with new equipment built to higher standards. An example of this is
14 in the UK where a total of Ł172 million is being invested in between 2011-2023 to raise flood protection of
15 substations to be resilient to the 1 in 1000 year flood (ENA, 2015). Electricity cables can be upgraded in
16 anticipation of reduced efficiency in a warmer climate, although in many locations this may be achieved
17 autonomously to meet growth in electricity demand (Fu et al., 2017).

18

19 Fuels, including oil, natural gas, hydrogen, biomass, and CO2 prior to sequestration are delivered and
20 distributed by pipeline or transportation by road, rail and shipping. In addition to engineering improvements,
21 adaptation measures also include planning and preparation for service disruption by changing transport
22 patterns, increasing local storage capacities, and identifying and prioritising protection of critical transport
23 nodes (Wang et al., 2019b; Panahi, Ng and Pang, 2020).

24

25 Several options are available to reduce the impacts of reduced cooling water for thermoelectric power
26 generation, increases in water temperature, and lower flows for hydropower generation. These include (i)
27 switching from freshwater to seawater (if available) or air cooling; (ii) replacing once through cooling
28 systems with recirculation systems; (iii) replacing fuel sources for thermoelectric power generation; (iv)
29 increasing the efficiency of hydro and thermoelectric power plants; (v) relaxing discharge temperature rules
30 to allow warmer water to enter rivers; (vi) installation of screens to stop algae or jellyfish blooms clogging
31 intakes (vii) reducing power production and managing demand; and, (viii) changing reservoir operation rules
32 (where available). Shreshta et al. (2021) show that changing reservoir operation rules can offset reduced
33 water availability under RCP8.5 until 2050, but is insufficient by the 2080s. Van Vliet et al., (2016) showed
34 that a 10% increase in hydroelectric generation efficiency can compensate for reduced water availability in
35 most regions. Higher efficiency thermoelectric plans offset impacts under lower climate change scenarios but
36 are shown to be inadequate under RCP8.5 by the 2080s; whereas a switch to seawater and dry (air) cooling
37 provides a net increase under this scenario. However, these technologies can increase costs. Increasing the
38 temperature of water discharged from the power station can have negative environmental impacts (Thome et
39 al., 2016; Yang et al., 2015).

40

41 Longer term systemic strategies could include a combination of increased network redundancy and
42 decentralization of generation locations (Fu et al., 2017), or the use of `defensive islanding' which involves
43 splitting the network into stable islands in order to isolate components susceptible to failure and
44 subsequently trigger a cascading event (Panteli et al., 2016). Smart grids are being increasingly deployed
45 within municipalities to provide more efficient management of supply and demand and mitigate greenhouse
46 gas emissions, however, there is limited understanding of their performance and reliability during floods and
47 other extreme weather events (Vasenev, Montoya and Ceccarelli, 2016; Feldpausch-Parker et al., 2018).

48

49 Adaptation and preparedness at the household level can minimize impacts during power outages, but
50 neighbourhood level assistance may be more appropriate to ensure support for vulnerable households, and
51 coordination of action and information (Ghanem, Mander and Gough, 2016). More generally, it is important
52 for responder organisations integrate energy needs in disaster preparedness and response plans. Whilst over
53 the longer term, reducing household and industrial demand for energy supply will reduce the need for capital
54 investments and upgrades (Fu et al., 2017).

55

56 Providing a reliable and resilient power supply is crucial to economic and social development (Fankhauser
57 and Stern, 2016). Furthermore, there are co-benefits from the use of low carbon energy systems (Chapter 8,

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 1 WGIII AR6). For example, solar-charged street lamps and household lighting provides reliable nighttime
 2 lighting providing safety, security and resilience to disruption of network power supplies (Burgess et al.,
 3 2017). At larger scales, deploying solar power on building roofs, reduces energy demand for cooling by 12%
 4 and lowers the urban heat island and thereby has health benefits (Masson et al., 2014a). In the USA,
 5 construction of solar panels over 200millin parking spaces would generate a quarter of the country's
 6 electricity supply (Erickson and Jennings, 2017).

 7

 8 As shown in Table 6.3 access to energy supply varies considerably. In particular, many African countries
 9 require substantial energy infrastructure to support their economic development. The combination of smart
10 technologies with solar and other renewable generation provides a huge opportunity (Anderson et al., 2017;
11 Kolokotsa, 2017). However, care must be taken in rapidly developing cities as failure to ensure energy
12 access during urbanization can reduce resilience (Ürge-Vorsatz et al., 2018).

13

14 6.3.5.5 Transport

15

16 A wide range of adaptation options are available for transport infrastructure and most provide a good benefit
17 cost ratio (Doll, Klug and Enei, 2014; Forzieri et al., 2018). Options include upgrading infrastructure (which
18 can often be achieved autonomously as part of standard repair and replacement schedules), strengthening, or
19 relocating (critical) assets. Adaptation of road and rail networks in Australasia includes re-routing, coastal
20 protection, improved drainage, and upgrading of rails (Table 11.7. In areas with substantial infrastructure
21 deficits, such as much of Africa, investments in public transport and transit-oriented development are
22 highlighted as desired mitigation-adaptation interventions within cities of South Africa, Ethiopia, and
23 Burkina Faso (Section 9.8.5.3). Adapting low carbon transport infrastructure will be crucial to ensure
24 resilience to climate change impacts whilst simultaneously delivering mitigation goals (Shaheen, Martin and
25 Hoffman-Stapleton, 2019; Costa et al., 2018).

26

27 Wright et al. (2012) calculated that strengthening bridges in the USA would cost $140-$250bn by 2090 (or
28 several billion dollars a year), but costs are reduced by 30% if interventions are made proactively. Koks et al.
29 (2019) calculate a benefit cost ratio of greater than one for over 60% of the world's roads exposed to
30 flooding. The greatest benefits from adaptation of the global road network are in low- and middle-income
31 countries where reductions in flood risk are typically between 40-80%. Pregnolato et al. (2017) showed that
32 in the city of Newcastle upon Tyne (UK) two carefully targeted interventions at key locations to manage
33 surface water flooding reduced the impacts of the 1 in 50-year event in 2050 by 32%. In permafrost regions
34 geo-reinforcement, foundation and piles can be strengthened (Trofimenko, Evgenev and Shashina, 2017),
35 whilst passive cooling methods, including high-albedo surfacing, sun-sheds, and heat drains can cool
36 infrastructure (Doré, Niu and Brooks, 2016).

37

38 Hanson and Nicholls (2020) calculate the total global investment costs for port adaptation to sea-level rise
39 and provision of new areas US$223-768bn by 2050. However, adaptation of existing ports is only 6% of this.
40 Yesudian and Dawson (2021) estimate the cost of maintaining present levels of flood risk in 2100 for the
41 global air network will cost up to $57bn (Monioudi et al., 2018; Esteban et al., 2020b).

42

43 New technologies and design innovations can improve the resilience of cars, trains, boats and other vehicles
44 to cope with more extreme weather. Mobility transitions have the potential to improve mobility and
45 accessibility, to influence urban form and to reduce vehicular use (and thereby infrastructure degradation),
46 vehicle miles travelled and vehicle-based emissions (Sperling, Pike and Chase, 2018). For example, use of
47 electric vehicles, hydrogen vehicles, and greater uptake of public transport and other vehicles that reduce
48 exhaust head emissions reduces the urban heat island (Kolbe, 2019) Carsharing can reduce carbon emissions
49 by over 50% (Shaheen, Martin and Hoffman-Stapleton, 2019). Ride-hailing - matching nonprofessional
50 drivers of private vehicles with paying passengers - positively impacts low-income, low car ownership
51 households in Los Angeles (Brown, 2018), and fills market gaps in cities where public transit infrastructure
52 is inadequate, unreliable or unsafe (Suatmadi, Creutzig and Otto, 2019; Vanderschuren and Baufeldt, 2018),
53 but can also create a precarious and insecure job market that impacts wellbeing (Fleming, 2017). Whether
54 the resulting impacts are positive or negative, largely depends on local, national and international policy and
55 practices.

56

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 1 Safe and convenient walking and cycling (and public transport) infrastructure in cities reduces carbon
 2 emissions and urban heat island intensity, but also improve cardiovascular capacity which reduces heat stress
 3 (Schuster et al., 2017). In some regions warmer weather may bring opportunities for increased uptake of
 4 cycling and walking, though precipitation or thermal discomfort caused by high temperature and humidity
 5 can reduce the use of active travel modes for commuting and recreation (Chapman, 2015). Shaded
 6 pavements and lanes, and measures to mitigate the urban heat island can reduce risks to disruption of active
 7 travel thereby also enhancing mitigation (Wong et al., 2017).

 8

 9 Full system re-design may enable the greatest resilience but it does not usually have a good benefit cost ratio
10 (Doll, Klug and Enei, 2014). Moreover, Caparros-Midwood et al. (2019) show that transport infrastructure
11 planners will not always be able to resolve trade-offs between managing climate risks and mitigating
12 greenhouse gases without tackling other sectors. However, infrastructure planners should continually seek
13 opportunities for positive infrastructure lock-in where available (Ürge-Vorsatz et al., 2018).

14

15 6.3.5.6 Water and Sanitation

16

17 Adaptation to water scarcity can be through measures to increase supply (e.g. water storage, rainwater
18 harvesting, desalination, river basin transfers, increased abstraction, reduce pollution of water sources), or
19 manage demand (e.g. reduce leakage lower consumption, use of water efficiency devices, greywater reuse,
20 behaviour change). A combination of these measures is usually required (e.g. Ives, Simpson and Hall, 2018;
21 Dirwai et al., 2021; Wang et al., 2018a). Reliable, well adapted, water and sanitation services support
22 economic growth, public health, reduced marginalisation and poverty, can lower energy use and improve
23 water quality (Campos and Darch, 2015; Miller and Hutchins, 2017; Jeppesen et al., 2015; Hamiche,
24 Stambouli and Flazi, 2016).

25

26 Globally, water sector adaptation costs are estimated to be $20 billion per year by 2050 (Fletcher, Lickley
27 and Strzepek, 2019). Globally, the budget required by 2030 for water infrastructure (new and refurbishment)
28 is more than half of the budget required for all infrastructure (Koop and van Leeuwen, 2017). For OECD
29 countries water adaptation increases costs by 2%, but this proportion is far higher for developing nations
30 (Olmstead, 2014).

31

32 A number of adaptation actions are available to reduce the impacts of floods on water and sanitation
33 infrastructure. Active management reduces blockages in water infrastructure, and protect related services
34 such as roads and culverts which are essential to ensure the operation of onsite sanitation infrastructure
35 (Capone et al., 2020). The impact of floods for onsite or sewerage systems can be lowered by reducing or
36 eliminating excreta from the environment through regular maintenance, cleaning, and clearing of blockages
37 (O'Donnell and Thorne, 2020; Borges Pedro et al., 2020).

38

39 Infrastructure to protect key assets such as water and wastewater treatment plants or pumping stations has a
40 high cost but benefits all connected households and reduces pollution from flood events. In well-regulated
41 water sectors, there has been an increasing focus on such investments (Campos and Darch, 2015). Whereas
42 more diffused cheaper interventions can reduce flood water ingress to domestic toilets (Irwin et al., 2018).
43 Luh et al. (2017) found that protected dug wells were one of the least resilient technologies, whereas piped,
44 treated, utility managed surface water systems had higher resilience.

45

46 Protecting water sources from pollution is even more important in a warmer climate that increases the
47 frequency of algal blooms. Individual assets such as water intake pipes can be protected using screens (Kim
48 et al., 2020a), whereas basin scale land management is required to reduce nutrient load from runoff (Me et
49 al., 2018), whilst injecting water or installing barriers can protect coastal aquifers from salinization (Siegel,
50 2020).

51

52 More radical structural interventions may be needed in the longer term, but would need to be planned and
53 delivered in coordination with investments in other sectors, particularly housing (Lüthi, Willetts and
54 Hoffmann, 2020). As an interim measure, sanitation services with a lower reliance on fixed infrastructure, or
55 container based sanitation could be appropriate in many urban areas that are badly affected by flooding
56 (Mills et al., 2020).

57

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 1 Other actions include use of adaptive planning (Evans, Rowell and Semazzi, 2020), integration of measures
 2 of climate resilience into water safety plans (Prats et al., 2017), as well as improved accounting and
 3 management of water resources (Lasage et al., 2015). Policy prescriptions on technologies for service
 4 delivery, and changes in management models offer potential to reduce risks, particularly in low-income
 5 settings (Howard et al., 2016). Where formal sewerage provision is lacking, community based adaptation
 6 that incorporates both the function of the sanitation system as well as the vulnerability of users (e.g., women,
 7 children, elderly, ill or disabled) into the design is essential (Duncker, 2019).

 8

 9 6.3.5.7 Flood management

10

11 Cities are deploying a broad range of strategies to adapt infrastructure to flooding, with hard engineering
12 approaches (e.g. dikes and seawalls) increasingly complementing soft approaches, including planning and
13 use of nature based solutions, that emphasize natural and social capital (Jongman, 2018; Sovacool, 2011).
14 The infrastructure can alter downstream risks and lead to increased residual risk by encouraging more
15 floodplain construction (Miller, Gabe and Sklarz, 2019; Ludy and Kondolf, 2012). Physical infrastructure is
16 highly cost effective for large settlements, but not always for small settlements (Tiggeloven et al., 2020) and
17 can be inaccessible to poorer communities (Sayers, Penning-Rowsell and Horritt, 2018; Van Bavel, Curtis
18 and Soens, 2018). It is often inflexible once installed but new designs and adaptive pathways are emerging
19 (Anvarifar et al., 2016; Kapetas and Fenner, 2020).

20

21 As urban areas have expanded, so too have the number of vulnerable assets, and efforts may now emphasize
22 reducing construction in high risk regions (Paprotny et al., 2018a). The National Flood and Coastal Erosion
23 Risk Management Strategy for England, for example, calls for reductions in inappropriate developments in
24 floodplains (Kuklicke and Demeritt, 2016; UK Environment Agency, 2020). Because climate change
25 increases the flood risk profile of certain regions, reconsideration of design criteria has become more
26 common (Ayyub, 2018). New York City now requires the sewer system currently designed for hydraulic
27 capacity in 5-year design life should be designed for 50-year design life taking into account climate changes
28 over that period (NYC, 2019).

29

30 Adaptation strategies are diverse and often involve hybrid physical and nature-based solutions, and
31 increasingly integrated management plans that consider both flood prevention and designing infrastructure
32 and supporting people to cope with floods when they occur. Adaptation typically focuses on (i) increasing
33 the standard of protection to compensate for the increased magnitude of extreme events; (ii) increased
34 maintenance to cope with increased frequency of extremes and changes in ambient conditions; (iii) changed
35 maintenance regimes from narrower maintenance windows e.g. as assets are used more frequently (Sayers,
36 Walsh and Dawson, 2015); (iv) land use planning and management to reduce exposure and manage
37 hydrological flows, and (v) raising awareness, preparedness, and incident management. In high population
38 areas, hard interventions such as dikes and levees are generally cost effective (Jongman, 2018; Ward et al.,
39 2017).

40

41 Prevention or attenuation solutions include: rooftop detention, reservoirs, bioretention, permeable paving,
42 infiltration techniques, open drainage, floating structures, wet-proofing, raised structures, coastal defences,
43 barriers, and levees, and have been deployed in diverse configurations, and environments, around the world
44 (Matos Silva and Costa, 2016). Barcelona (Spain) by the 1980s reached 90% impermeable surface cover, and
45 has recently begun implementing artificial detention, underground reservoir, and permeable pavement
46 technologies (Favaro and Chelleri, 2018; Matos Silva and Costa, 2016). Florida Power and Light (USA)
47 which provides service to approximately 10 million people, is investing $3b in flood protection and the
48 hardening of assets (for example, upgrading wooden polls to steel and concrete) (Brody, Rogers and
49 Siccardo, 2019). The City of Seattle recommends increasing preventative maintenance activities, the regular
50 review of appropriate pavement technologies, and modifications to subgrades and drainage facilities for high
51 risk areas (City of Seattle, 2017), whilst also providing benefits to transport disruption (Arrighi et al., 2019).
52 Adaptation in African cities is often dominated by informal responses (Owusu-Daaku and Diko, 2018). In
53 the absence of centralized responses, low-income residents in Nairobi (Kenya) dig trenches and construct
54 temporary dikes to protect homes, and in Accra (Ghana) the community has developed a range of social
55 responses including communal drains and local evacuation teams, to help protect people and critical
56 valuables, although these innovations require connection to city-wide infrastructure to effectively reduce
57 widespread risk (Amoako, 2018).

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 1

 2 More recent developments include sensor arrays to catalogue a river's reach and how changing hydraulics
 3 interact with roadways (Forbes et al., 2019). Kuala Lumpur's (Malaysia) Stormwater Management and Road
 4 Tunnel (SMART) during extreme rain events transitions the motorway to a stormwater conduit, an example
 5 of multifunctionality enabling agility (Isah, 2016; Markolf et al., 2019). Smart stormwater control systems
 6 are starting to use real time control to dynamically manage the retention and movement of water during
 7 storms, though uptake at large scales which provide the greatest improvements in performance have been
 8 limited (Xu et al., 2020b).

 9

10 In contrast to a "fail-safe" approach to design which emphasises strengthening infrastructure against more
11 intense environmental conditions, "safe-to-fail" flood strategies allow infrastructure to fail in its ability to
12 carry out its primary function but control the consequences of the failure. Examples include the use of a
13 bioretention basin in Scottsdale (Arizona, USA) to accommodate excess runoff and help drain the city; a
14 subsidy for affected farmers for lost crop production as part of the Netherlands' Room for the River
15 program; targeted destruction of a levee to control flooding in the Mississippi River Valley in 2011 (Kim et
16 al., 2019). Water Sensitive Urban Design, Low Impact Development, Sponge Cities, Sustainable Urban
17 Drainage, and Natural Flood Management, involve deployment of systems and practices that use or mimic
18 natural processes that result in the infiltration, evapotranspiration or use of stormwater to protect water
19 quality and associated aquatic habitat. These are being designed and implemented at increasingly ambitious
20 scales. For example, China's Sponge City initiative sets a goal of 80% or urban land able to absorb or reuse
21 70% of stormwater through underground storage tanks and tunnels, and use of pervious pavements, in
22 addition to nature-based solutions (Chan et al., 2018; Muggah, 2019). Similarly, several thousand Water
23 Sensitive Urban Design interventions have been implemented across the city of Melbourne (Kuller et al.,
24 2018).

25

26 6.3.5.8 Coastal Management

27

28 Physical coastal management infrastructure has significant benefits in reducing flood and erosion losses and
29 damage from storms. Physical infrastructure includes seawalls, dikes, breakwaters, revetments, groynes, or
30 tidal barriers. Adapted infrastructure can alter risks in morphologically connected areas, and lead to
31 increased residual risk by encouraging more construction in the coastal zone (Miller, Gabe and Sklarz, 2019;
32 Ludy and Kondolf, 2012). The infrastructure is highly cost effective for large settlements, but not always for
33 small settlements (Tiggeloven et al., 2020) and can be inaccessible to poorer communities (Fletcher et al.,
34 2016; Pelling and Garschagen, 2019).

35

36 Anticipated costs for this vary widely. For example, Hinkel et al. (2014) calculate that adaptation costs to
37 maintain current global levels of coastal flood protection would be 1.2­9.3% of Gross World Product but
38 protect assets in human settlements of $US21-210bn; Tiggeloven et al. (2020) calculate the cost of
39 adaptation to be US$176bn (although this would provide a Benefit to Cost Ratio of 106 under RCP8.5);
40 while Nicholls et al (2019) estimate that global coastal protection would cost substantially more, up to $18.3
41 trillion between 2015 to 2100 for RCP8.5 (this includes ranges of unit costs and maintenance costs which
42 have often been ignored).

43

44 Coastal protection infrastructure such as dikes and sluice gates can inhibit salinity intrusion through careful
45 management of water levels, this can provide co-benefits for flood risk reduction and agricultural
46 productivity but can also have negative impact on ecosystems (Renaud et al., 2015). Managed aquifer
47 recharge can be effective if the objective is to secure freshwater drinking supply (Hossain, Ludwig and
48 Leemans, 2018).

49

50 Physical infrastructure can provide substantial benefits, can be constructed quickly, and has enabled coastal
51 cities and settlements around the world to flourish and grow. Multifunctional physical infrastructure can also
52 provide economic and social co-benefits. These include integration of transport, recreation, agriculture e.g.
53 cattle pasture, founding for wind turbines, housing, office or industry into the coastal management
54 infrastructure (Anvarifar et al., 2017; Kothuis and Kok, 2017). However, physical infrastructures can also
55 disrupt natural processes, often leading to undesirable impacts such as pollution, degradation of ecosystems,
56 and displacement of erosion and flood risk to other locations (Wang et al., 2018b; Dawson, 2015; Nicholls,
57 Dawson and Day, 2015). Coastal management strategies that take a hybrid approach, integrating physical

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 1 and natural infrastructure, provide the best opportunities for managing risk and achieving wider socio-
 2 economic and environmental benefits (Depietri and McPhearson, 2017; Morris et al., 2018; Schoonees et al.,
 3 2019; Powell et al., 2019).

 4

 5 6.3.6 Cross-Cutting Themes

 6

 7 This section builds on 6.3.4 to offer two entry points for assessing urban adaptation that extend beyond
 8 individual infrastructure types and that demonstrate the interdependent and dynamic natures of urban
 9 systems.

10

11 6.3.6.1 Equity and Justice

12

13 Questions of equity and justice influence adaptation pathways for cities, settlements and infrastructure (see
14 also Chapter 8). Although infrastructure, ranging from social to ecological and physical to digital, can help to
15 reduce the impacts of climate change (Stewart and Deng, 2014; Baró Porras et al., 2021), there is limited
16 evidence of how infrastructures, implemented to reduce climate risk also reduce inequality. Rather, there is
17 more evidence to suggest that both adaptation plans and associated infrastructure implementation pathways
18 are increasing inequality in cities and settlements (Chu, Anguelovski and Carmin, 2016; Anguelovski et al.,
19 2016; Romero-Lankao and Gnatz, 2019). Social, economic and cultural structures that marginalize people by
20 race, class, ethnicity and gender all contribute in complex ways to climate injustices and need to be urgently
21 surfaced in order for adaptation options to shift to benefit those most vulnerable rather than mainly
22 benefitting the already privileged and maintaining the status quo (Thomas et al., 2019; Porter et al., 2020;
23 Ranganathan and Bratman, 2019). Innovation and imagination are needed in adaptation responses to ensure
24 that cities and settlements shift from perpetuating structural domination and inequality to fairer cities (Porter
25 et al., 2020; Henrique and Tschakert, 2019; Parnell, 2016b). To support these possibilities, this section
26 explores adaptation through the lens of distributive and procedural justice. Although not expanded on here,
27 spatial and recognition injustices are equally important (Fisher, 2015; Chu and Michael, 2018; Campello
28 Torres et al., 2020). Recognition can be supported through a capabilities approach that helps to bring
29 attention to past cultural domination and enable citizens to develop the functioning life they choose
30 (Schlosberg, Collins and Niemeyer, 2017). This brings a focus on local action emphasizing the relevance to
31 vulnerability reduction and resilience building of individual and local/community capacities and supporting
32 structures. This blurs the distinction between climate change adaptation and community development with
33 the former firmly embedded in the latter. Struggles for recognition are deeply political and central to
34 adaptation responses, which requires increased focus on power to support more equitable and just adaptation
35 (Nightingale, 2017). Justice question are not static, Box 6.4 overviews the implications of COVID-19 for
36 urban justice and vulnerability.

37

38

39 [START BOX 6.4 HERE]

40

41 Box 6.4: Adapting to Concurrent Risk: COVID-19 and Urban Climate Change

42

43 COVID-19 impacts have highlighted the depth and unevenness of systemic social vulnerability and the
44 compounding characteristics of contemporary development models with direct relevance to climate change
45 risk accumulation and its reduction (Patel et al., 2020b; Manzanedo and Manning, 2020; Bahadur and
46 Dodman, 2020). This is plain at the global level: of the estimated 119 to 124 additional people induced into
47 poverty by COVID-19 in 2020, South Asia and sub-Saharan Africa each contribute two-fifths (Lakner et al.,
48 2021). These are rapidly urbanizing and highly climate hazard exposed world regions indicating COVID-19
49 impacts may further concentrate risk in these regions. Within cities, COVID-19 and climate change risk and
50 loss is concurrent by gender, race and income or livelihood. For example, when vulnerable elderly
51 populations are simultaneously exposed to COVID-19 and heatwave risk. Globally, in 2020, about 431.7
52 million vulnerable people were exposed to extreme heat during the COVID-19 pandemic, including about
53 75.5 million during a July and August 2020 European heatwave with an excess mortality of over 9,000
54 people arising from heat exposure (Walton and van Aalst, 2020).

55

56 The pandemic has demonstrated the multiple, often reinforcing ways in which specific drivers of
57 vulnerability interact both in generating urban risk and shaping who is more or less able to recover (Phillips

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 1 et al., 2020b; Honey-Rosés et al., 2020) (see Section 6.2). Again, this is not a new lesson for urban climate
 2 change adaptation, but it is a lesson that has not yet been seen to enter into routine practice for urban
 3 adaptation. Two key challenges for climate change adaptation are the associations between COVID-19 risk
 4 and urban connectivity and overcrowding. Connectivity has been presented in urban adaptation policy as a
 5 virtue, a means to share risk and diversity inputs (Ge et al., 2019; Kim and Bostwick, 2020), COVID-19 has
 6 surfaced the unevenness with which people and places are connected and also the need to balance
 7 connectivity against risk transfer ­ through the failure of food supply chains or remittance flows as well as
 8 by the direct transfer of disease (Challinor et al., 2018). High density living has advantages for urban
 9 resource efficiency including benefiting climate change mitigation. When high density living is not
10 supported by adequate access to critical infrastructure (sufficient internal living space, access to potable
11 water and sanitation, access to open green space) this exacerbates overcrowding and generates vulnerability
12 to multiple risks ­ including climate change hazards and communicable disease (Bamweyana et al., 2020;
13 Hamidi, Sabouri and Ewing, 2020; Peters, 2020; Satterthwaite et al., 2020). Where overcrowding coincides
14 with precarious livelihoods, for example in informal settlements, risk is further elevated (Wilkinson, 2020).
15 Neighbourhood associations (a benefit of high density living) have been an important source of resilience
16 through providing trusted information, access to food and water for washing during the pandemic, serving
17 populations unable to access government or market provision (Pelling et al., 2021). Here local organising has
18 not only met gaps in service provision but opened dialogue to vision and organise for alternative
19 development futures. These distinctly urban challenges should be read as a sub-set of wider cross-cutting
20 lessons for recovery from COVID-19 (see Cross-Chapter Box COVID in Chapter 7).

21

22 Where responses to COVID-19 include addressing inequities in social infrastructure this opens a
23 considerable and potentially society-wide opportunity to reduce social vulnerability to climate change risks.
24 (see Cross-Chapter Box COVID in Chapter 7).

25

26 [END BOX 6.4 HERE]

27

28

29 Distributive justice calls attention to unequal access to urban services, land, capital and technology. Related
30 to this, exposure to health, flooding and drought risks of people living in low-income and informal
31 settlements is a growing concern, as is disaster preparedness and the ability to support the needs of
32 vulnerable groups such as the elderly, children and disabled, where data is often lacking (Lilford et al., 2016;
33 Castro et al., 2017). There are also differences in who benefits from infrastructures, as they are inherently
34 political, embedded in social contexts, politics and cultural norms (McFarlane and Silver, 2017) and often
35 tend to benefit those already privileged (Henrique and Tschakert, 2019). As an example, fixing water leaks
36 can depend as much on the politics of who is involved and whose knowledge is prioritised, as on the
37 technical aspects (Anand, 2015).

38

39 The quality and maintenance of infrastructure is often unequal across cities benefiting some and increasing
40 vulnerability of others. Some property is seen as dangerous and of lower value if highly exposed to risk
41 (Wamsley et al., 2015). Similarly, areas suffering from disinvestment in infrastructure, might have a high
42 risk of flooding (Haddock and Edwards, 2013). Zoning and land use trade-offs have been seen to be
43 unequally skewed in favour of prime real estate and economically valuable assets (e.g., protecting factories
44 and refineries from flooding) (Anguelovski et al., 2016; Carter et al., 2015). Urban planning reforms are
45 therefore central to building a fairer urban adaptation response (Parnell, 2016b).

46

47 Infrastructure is often not adequately implemented in low-income urban areas and not equally accessible to
48 all (Meller et al., 2017). For example, low-income neighbourhoods often have less green space and therefore
49 less associated cooling benefits. Even in high-income areas, there is often unequal access to services. For
50 example, an assessment of sustainable urban mobility plans in Portugal showed that some areas have
51 considered equity in their plans and increased access for disadvantaged users including the elderly and
52 disabled, but in other cities this is lacking (Arsenio, Martens and Di Ciommo, 2016). Understanding who has
53 access to what infrastructure can help to redress the drivers of social vulnerability, that are central to just
54 urban adaptation (Michael, Deshpande and Ziervogel, 2018; Shi et al., 2016).

55

56 Changing land use and increasing green spaces to reduce climate risks and attract investments and job
57 opportunities has increased real estate values, triggered climate gentrification in some areas (Keenan, Hill

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 1 and Gumber, 2018) and decreased access to affordable housing in other areas (Larsen, 2015; Carter et al.,
 2 2015). Displacement through evictions and relocations linked to land use conversion and resettlement in the
 3 name of adaptation has also increased people's vulnerability (Anguelovski et al., 2016; Henrique and
 4 Tschakert, 2019).

 5

 6 Understanding social and economic elites and their investment in infrastructure has implications for
 7 distributive justice, particularly when there is secession from public infrastructure services that has financial
 8 implications for viability (Romero-Lankao, Gnatz and Sperling, 2016). In the case of the 2015-17 Cape
 9 Town drought, wealthy households secured their water needs through off-grid technologies such as rainwater
10 tanks and boreholes. Although this resulted in more water being available in the dams, it also led to less
11 revenue being collected for municipal water and less ability to cross-subsidize water for poor households
12 (Ziervogel, 2019b; Simpson, 2019; Bigger and Millington, 2019). More attention needs to be paid to how
13 shifts in infrastructure are serving the interests of urban elites, often driving by the state, and failing to
14 adequately consider the needs of the disadvantaged (Bulkeley, Castán Broto and Edwards, 2014; Ajibade,
15 2017; Shi et al., 2016). Equally, more risk-reducing infrastructure is needed across all urban areas (Reckien
16 et al., 2018a).

17

18 Procedural justice, which focuses on the institutional processes by which adaptation decisions are made,
19 brings attention to the lack of opportunity for engaging in political decision-making and limited
20 representation of diverse voices in cities and settlements, and in relation to investment in infrastructure
21 (Coates and Nygren, 2020; Henrique and Tschakert, 2019). Even when inclusive adaptation processes are
22 run, they seldom produce procedurally just outcome (Malloy and Ashcraft, 2020). Understanding who is
23 excluded and included is important (Sara, Pfeffer and Baud, 2017). One example, are the increasing numbers
24 of migrants who are confronted with lack of access to citizenship rights and housing tenure (Romero-Lankao
25 and Norton, 2018). Often, migrants are not allowed to formally claim public provisions in health, finance,
26 and shelter (Chu and Michael, 2018). Further, migrants and their settlements are likely unrecognized in
27 spatial or infrastructure development plans. In this context, social infrastructure, zoning and land use
28 planning for climate adaptation has triggered inequity through omission, as some planning process have been
29 racialized and excluded groups such as migrants and ethnic minorities (Anguelovski et al., 2016). Urban
30 adaptation policy-making processes that explicitly integrate multiple stakeholder interests can help to
31 balance top-down solutions (Reckien et al., 2018a).

32

33 Identifying who is least able to adapt to climate risks sufficiently is important (Thomas et al., 2019). Some
34 people may have few opportunities to relocate away from flooded areas in the long-term or to evacuate in the
35 short term. It is also harder for many from low-income areas to rebuild after an extreme event. Lack of
36 housing tenure and sub-standard housing has been shown to limit the ability of residents to improve and
37 manage their landscapes and therefore it is hard for them to enhance energy efficiency (Dempsey et al.,
38 2011). Access to information is critical for adapting to climate risk and reducing vulnerability to hazards, yet
39 access to this information is often not equally available (Ma et al., 2014). For example, low literacy can
40 hamper ability to respond to early warning information (Dugan et al., 2011). In other instances, racial
41 violence has surfaced during disasters, with black victims' lives being seen as less important than others
42 (Anderson et al., 2020).

43

44 When looking at justice issues in urban adaptation it is important to recognise that the adaptation of one
45 individual or household may lead to maladaptation and negative impacts elsewhere (Holland, 2017;
46 Limthongsakul, Nitivattananon and Arifwidodo, 2017; Atteridge and Remling, 2018). For example, the case
47 of an area of peri-urban Bangkok experiencing localized flooding due to unregulated private sector
48 development saw households take both individual action (building flood walls around homes, digging
49 temporary drainage swales in the carriageway) and collective action (petitioning authorities, pumping water
50 into vacant land). These actions, to a certain extent, merely displaced the flood water to other areas, or
51 created new problems by damaging the carriageway, creating negative impacts on other households and the
52 wider community. However, ultimately it was the actions of improperly-regulated private sector developers
53 driving the need for this autonomous adaptation (Limthongsakul, Nitivattananon and Arifwidodo, 2017).

54

55 One of the tensions that emerge when addressing injustice is that the global provision of modern
56 infrastructure is increasingly seen as unfeasible. It is unfeasible, both in terms of the current high emissions
57 associated with infrastructure (World Bank, 2017) as well as the centralized, high standard ideal (Lawhon,

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 1 Nilsson and Silver, 2018; Coutard and Rutherford, 2015). Decentralisation is increasingly needed, which the
 2 urban poor already engage in through their use of `informal' infrastructure technologies, given their limited
 3 access to infrastructure networks. Transformative adaptation pathways that reduce climate risk whilst
 4 reducing inequity require an approach that sees infrastructure as inherently social and political.

 5

 6 6.3.6.2 Mitigation and Adaptation

 7

 8 As analytical concepts, mitigation and adaptation have helped, over the years, to structure thinking and
 9 action around climate change. However, since AR5 there has been a growing debate about the adequacy of a
10 neat separation between adaptation and mitigation (Castán Broto, 2017).

11

12 The delivery of climate change action has revealed numerous co-benefits between adaptation and mitigation,
13 around diverse areas such as implementing nature-based solutions and delivering health and development
14 benefits (Ürge-Vorsatz et al., 2014; Suckall, Stringer and Tompkins, 2015; Puppim de Oliveira and Doll,
15 2016; Spencer et al., 2017). There has been a strong interest in delivering development benefits alongside
16 climate mitigation, thus benefiting the overall infrastructure base (Suckall, Stringer and Tompkins, 2015).
17 Some of these co-benefits have also emerged in experiences of urban planning, pointing towards the
18 dilemma of separating adaptation and mitigation in a context in which integration, rather than an analytical
19 differentiation, was seen as being required to transcend work in silos (Aylett, 2015). Because urban planning
20 needs to carefully consider long timescales, the neat separation between mitigation and adaptation runs
21 counter to integrated forms of planning that can consider scales (time and space) carefully and that are aimed
22 to deliver the sustainable city as a whole (Solecki et al., 2015; Grafakos et al., 2020).

23

24 For example, the ideas of climate resilient development and climate compatible development help planners
25 to consider the simultaneous wins that emerge between adaptation, mitigation, and development, requiring
26 institutional building and partnerships to deliver triple win solutions (Stringer et al., 2014; Seo, Jaber and
27 Srinivasan, 2017; Mitchell and Maxwell, 2010). While the evidence base for the actual possibility of
28 achieving such triple wins remains scarce (Tompkins et al., 2013; Sharifi, 2020), emerging examples show
29 important developments. For example, establishing safe and convenient walking and cycling infrastructure
30 can lead to improvements in population health, thereby highlighting the close interaction between urban
31 land-use, infrastructure and population health (Schuster et al., 2017); while clean cooking has the potential to
32 deliver positive health outcomes alongside improvements in air quality and emissions reductions and through
33 reducing pressure on woodland as a fuel source for expanding urban populations (Msoffe, 2017).
34 Furthermore, active transport infrastructure reduces air pollution and related health risk, and helps to mitigate
35 further climate change (Schuster et al., 2017). These are supported by city networks such as the C40 Clean
36 Air Cities Declaration and the Clean Air Coalition that complements WHO guidelines and standards for
37 example through the Breathe Life Campaign. In conclusion, in both urban environments and infrastructural
38 sectors, triple wins are only realizable through broader perspectives that link climate compatible
39 development to institutional change or the achievements of wider welfare objectives such as those enshrined
40 in the United Nations 2030 Agenda of Development (Castán Broto et al., 2015; England et al., 2018)
41 (medium evidence, high agreement).

42

43 The aspiration to deliver climate change action within a broader agenda of transformative change, introduced
44 in the SREX report, received renewed attention after the publication of IPCC Special Report on Global
45 Warming of 1.5°C, which argues for a focus on urban transformations and highlighted that informal
46 settlements were vital for understanding the delivery of these transformations. Deep decarbonization has
47 emerged as a new idea that regards the development of low or zero carbon pathways as a condition for good
48 adaptation in the long term. Decarbonization becomes urgent in the face of growing impacts attributable to
49 climate change (Ribera et al., 2015; Bataille et al., 2016; Wesseling et al., 2017). Urbanization opens
50 opportunities for deep mitigation in low impact developments, and hence, it is imperative to understand the
51 implications of those opportunities for climate action (Mulugetta and Broto, 2018). These gains are not
52 limited to urban areas. The reliance on connected urban-rural systems for water, food and fuel has led to city
53 government and urban based businesses supporting landscape adaptations in rural hinterlands with strong
54 potential for mitigation and rural development cobenefits. Water Funds bring downstream urban public and
55 private finance to support upstream, rural residents to make land-use and agricultural management decisins
56 to avoid damaging run-off, soil erosion and downstream sedimentation with reduction in water quality and
57 increased flood risk. There are more than 30 Water Funds in Latin America and sub-Saharan Africa. These

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 1 operate at landscape scale, the Upper Tana-Nairobi Water Fund, Kenya (Vogl et al., 2017) planned for a
 2 US$10 million investment in water fund-led conservation interventions with a projected return of US$21.5
 3 million in economic benefits over a 30-year timeframe (Apse and Bryant, 2015). However, these investments
 4 do not occur where communities lack funding or the institutions to direct funding from downstream
 5 beneficiaries to upstream residents (Brauman et al., 2019).

 6

 7 6.3.7 Climate Resilient Development Pathways

 8

 9 Table 6.6 represents the contribution of 21 adaptation measures identified in this chapter to 17 components
10 of Climate Resilient Development (CRD). Climate Resilient Development brings together the aims of
11 climate adaptation, climate mitigation, sustainable development and social justice (Singh and Chudasama,
12 2021). This provides a first assessment of the viability of adaptation to cities, settlements and key
13 infrastructure as a part of global transition to sustainability (see also Cross-Chapter Box FEASIB in Chapter
14 18).

15

16 Two overarching messages and one key consequence for planning arise from Figure 6.4. First, urban
17 adaptation measures can offer a considerable contribution to Climate Resilient Development. Second, this
18 potential is realised by adaptations that extend predominant physical infrastructure approaches to also deploy
19 nature based solutions and social interventions. The consequence for planning is support for comprehensive
20 monitoring and joined-up evaluation across the multiple components of Climate Resilient Development as
21 well as between the sectors that contribute to adaptation.

22

23 Table 6.6 shows adapting key grey/physical infrastructure (built form and design, ICT, energy, transport,
24 water and sanitation) is fundamental to Climate Resilient Development. This provides resilience to a range of
25 hazards, with benefits to livelihoods, social capital and health and provides benefits for the adaptation of
26 other, connected infrastructure systems. Challenges to the contributions of grey/physical infrastructure,
27 where adaptation through nature based solutions and social policy offer alternatives are: a lack of flexibility
28 post-deployment constraining ability to flex as climate and vulnerability change; risk transferred to other
29 people/places, not resolved; negative ecological consequences; and, limited evidence of targeting marginality
30 and inequality.

31

32 The significance of a Climate Resilient Development lens for the evaluation of adaptation strategy can be
33 seen in approaches to riverine and coastal flooding. This viewpoint brings physical (e.g. embankments and
34 defenses), nature based (e.g. mangrove stands) and social policy (livelihood and social protection) options
35 together. The benefits of physical infrastructure interventions for strengthening existing livelihoods and
36 protecting health, for being deployable at scale and supporting other infrastructures to adapt are recognised
37 and set these against challenges including hazard generation and risk transfer, limited flexibility, ecological
38 harm, carbon costs and an undermining of social inclusion and accountability. Final evaluations will be
39 determined by individual contexts raising the importance of comprehensive monitoring of existing urban
40 systems adaptation interventions and their association with ongoing development processes and outcomes
41 (see Section 6.4).

42

43 The most consistent limit for all urban systems infrastructure types is in risk transfer. Current adaptation
44 approaches in cities, settlements and key infrastructure have a tendency to move risk form one sector or
45 place to others. With the exception of social infrastructure the observed contribution of adaptation to social
46 transformation is also limited. There are consequences for equity and sustainability as the impacts of climate
47 change increase, and implications for evaluation and planning to work across adaptation interventions and
48 connect with social and environmental policy and practice.

49

50

51

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1 Table 6.6 Urban Climate Resilient Development

2

3

4 Table Notes:
5 Overall confidence: Medium agreement - medium evidence. Supplementary Material provides a detailed analysis
6 including definitions for each component of Climate Resilient Development and for each of the 357 entries an
7 underlying explanatory statement linked to key evidence. Analysis was by Chapter 6 Lead and Contributing Authors.

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 1 6.4 Enabling Conditions for Adaptation Action in Urban Areas, Settlements, and Infrastructure

 2

 3 This section assesses the effectiveness of efforts to create enabling conditions for adaptation. New policy
 4 innovations like National Urban Policies are emerging to address the multi-level governance demands of
 5 climate change (UN-Habitat, 2020; Kinyanjui, 2020). There is no one-size-fits-all approach to deliver
 6 adaptation that will fit every case because the local conditions of implementation bear a strong influence on
 7 adaptation's feasibility and impacts (Archer et al., 2014). Ways to foster adequate enabling conditions for
 8 adaptation are well-documented (Masson-Delmotte and Waterfield, 2018 Ch.4). These often include
 9 integrated planning, multi-agency working and multi-scale and sector action. Existing techniques can be
10 shared as well as new innovations taken-up (Maxwell et al., 2018).

11

12 Adaptation in urban areas and settlements can be incremental (when it addresses the causes of problems but
13 without fundamentally changing the social and political structures that drive it, for example through planning
14 or new regulations), reformist (when it changes the features that cause problems but without fundamentally
15 changing the structures), or transformative (when it addresses fundamental systems attributes and outcomes
16 such as reducing inequality, in political and socio-economic structures or enhancing wellbeing (Mendizabal
17 et al., 2018; Rosenzweig and Solecki, 2018) which change the situation completely) (Heikkinen, Ylä-Anttila
18 and Juhola, 2019; Roberts and Pelling, 2020; O'Brien, Selboe and Hayward, 2018). In the context of the
19 Sustainable Development Goals mission to leave-no-one behind, transformative adaptation addresses
20 fundamental systems' functions to enable enhanced social justice and socio-ecological wellbeing.
21 Incremental adaptation actions seeks to maintain the essence and integrity of a system or process at a given
22 scale (see glossary). Adaptation that seeks only to defend existing development status will not contribute to
23 enhanced wellbeing and is not transformative, even if fundamental infrastructure engineering or legislative
24 systems are changed to maintain the status quo in the face of increasing risk (Mendizabal et al., 2018).

25

26 City populations, and non-state actors together with local and regional governments can play an essential
27 role in creating enabling conditions for action, including for example civil society mobilizing concerns of
28 marginalized voices and future generations- as indicated in the worldwide student mobilizations against
29 climate change (Wood, 2019; Maor, Tosun and Jordan, 2017; Cloutier, Papin and Bizier, 2018; Prendergast
30 et al., 2021), which may then be prioritised by local and regional governments. National governments also
31 play a crucial role for example in facilitating resources and finance for urban adaptation actions, alongside
32 financial organizations and the business sector (see 6.4.5). The section starts assessing adaptation
33 experiences in cities, settlements, and infrastructures since the AR5, before reviewing evidence of how to
34 foster enabling conditions for adaptation through institutionalization, governance capacity, finance,
35 evaluation, and social learning.

36

37 6.4.1 Adaptation Experiences in Cities, Settlements and Infrastructures

38

39 Since AR5, there is increasing evidence that successful adaptation to climate change is context-specific and
40 responsive to the particular needs of urban locations. This section assesses the contributions of key urban
41 actors ­ local government, civil society and the local private sector ­ in enabling adaptation. Wider
42 influences from national government cross-cut this and discussed on international agencies, including
43 through finance is assessed in Section 6.4.5.

44

45 The literature on the governance of adaptation has grown since the AR5, though with few cases from cities
46 and settlements in the Middle East, North Africa, Central Asia, and former USSR countries. Potential
47 reasons for the continued lack of studies in these areas include the centralized character of decision-making
48 systems in countries in these regions and the early stage of adaptation planning in these urban areas (Clar,
49 2019; Mitchell and Laycock, 2019; Olazabal et al., 2019a).

50

51 Flexible institutions that allow for both top-down and bottom-up action can bring capacities together from
52 across levels of government and actors within a settlement (Sharifi and Yamagata, 2017). Predominant
53 planning and capacity-building strategies, however, lack the flexibility to address the needs of a rapidly
54 changing environment (Carter et al., 2015; Dhar and Khirfan, 2017b; Juhola, 2016). Efforts to adapt to new
55 challenges may have to speed up. This is especially in urban areas and settlements with lower levels of
56 development and experiencing rapid urbanization, growing inequality and exposure to multiple hazards
57 (Dulal, 2019; Grafakos et al., 2019; Solecki et al., 2018). Even within cities that share similar characteristics

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 1 there are considerable differences in the level of investment in adaptation (Georgeson et al., 2016). There is
 2 also a danger that uncoordinated actions for climate change mitigation and adaptation may constrain future
 3 adaptation opportunities or create maladaptation (Juhola et al., 2016). The evidence emerging since the AR5
 4 suggests that institutional change can be accelerated by closer collaboration between the diverse actors and
 5 deployment of the diverse approaches that can deliver adaptation.

 6

 7 6.4.1.1 Experiences of adaptation action in sub-national governments

 8

 9 The assessment of cases of local adaptation demonstrates that most urban adaptation is led by local
10 governments (although the local government is also a heterogeneous category and local governance
11 arrangements may vary across administrative and political contexts) (high confidence) (Amundsen et al.,
12 2018; Lesnikowski et al., 2021). Local government reform at different levels can improve local adaptation,
13 whether this is by strengthening specific teams or building cross-departmental linkages (high confidence)
14 (Paterson et al., 2017; Shi, 2019; Wamsler and Raggers, 2018). Adaptation success often depends on having
15 political champions driving the adaptation agenda alongside measures such as access to a knowledge base,
16 resources at hand, political stability, and the presence of dense social networks that can be supported through
17 local government reform (Pasquini et al., 2015). Aligning adaptation objectives with other potential benefits
18 of sustainable development also supports adaptation. Specifically, policies and plans that link adaptation to
19 the objectives of Agenda 2030 supports action at the local level (UN-Habitat, 2016b). Showing the economic
20 benefits of adaptation is a strategy for local institutions to gain support for adaptation action. For example,
21 local governments in Surat, Indore, and Bhubaneswar in India linked adaptation to local development needs
22 in experiments that facilitated accessing human and finance resources, at the local, national and international
23 levels (Chu, 2016b). However, linking adaptation to co-benefits may also divide efforts and reduce the
24 effectiveness of adaptation actions. For example, urban land use planning and management in Ambo town,
25 Ethiopia resulted in the implementation of urban greening projects, but these projects did not directly address
26 the climate-related disaster risks affecting the settlement, including urban flooding, water stress, and water
27 shortages, increased urban heat, wind and dust storms (Ogato et al., 2017).

28

29 Multi-level governance measures that support local governments can foster robust adaptation approaches and
30 address risks and vulnerabilities across scales (high confidence) (Westman, Broto and Huang, 2019; Hardoy
31 et al., 2014; Romero-Lankao and Hardoy, 2015). Effective action by local government requires national
32 government's support (medium confidence). For example, Araos et al (2017) documents the case of Dhaka,
33 Bangladesh where a national plan prioritizes measures for protecting coasts and agricultural production. In
34 this context, the local government has minimal access to human and financial resources. Without national
35 support, the local government struggles to coordinate action amongst different stakeholders. National urban
36 adaptation directives can influence municipal governments' action and planning but evidence suggests that
37 national policy alone is not sufficient to deliver action on the ground without understanding local conditions
38 (high confidence) (Archer et al., 2014; Lehmann et al., 2015).

39

40 There are barriers for municipal adaptation plans to deliver effective adaptation outcomes and implemented
41 actions often diverge from plans (see 6.4.6). For example, a comparison of adaptation plans and budget
42 expenditures of six metropolitan cities in South Korea between 2012­2016 showed that the implementation
43 of adaptation programs diverged substantially from the original plans, both in terms of total spending and
44 sector-specific spending (Lee and Kim, 2018). Often, a focus on institutional change and reform limits
45 attention to more practical aspects of adaptation that improve communities' resilience (Castán Broto and
46 Westman, 2020). Adaptation actions, even where financed effectively, do not always deliver positive
47 outcomes (high confidence) (Reckien et al., 2015; Woodruff and Stults, 2016; Uittenbroek, 2016; Aguiar et
48 al., 2018; Reckien et al., 2018a; Olazabal et al., 2019b; Campello Torres et al., 2021) (see also 6.4.7).

49

50 6.4.1.2 The role of non-state actors in local adaptation

51

52 There are multiple actors, other than local governments that can deliver adaptation action including
53 businesses, not for profit organizations and trade unions (high confidence) (Giordano et al., 2020; Eakin et
54 al., 2021). Empirical evidence since the AR5 highlights the role of communities, universities, the private
55 sector, and transnational networks in adaptation (Hunter et al., 2020; Bäckstrand et al., 2017). Non-state
56 actors are particularly important in enabling adaptation by linking government agencies with low-income

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 1 and marginalised communities including those living in informal settlements (Kuyper, Linnér and Schroeder,
 2 2018; Khosla and Bhardwaj, 2019).

 3

 4 Since AR5 civil society and private actors have emerged as core knowledge holders and drivers of
 5 experimentation, even succeeding in changing public policy in the process (Klein, Juhola and Landauer,
 6 2017; McKnight and Linnenluecke, 2016; Mees, 2017). Previous IPCC Assessment Reports noted that civil
 7 society actors enable local risk awareness, sensitization, adaptive capacity and generate locally-based
 8 innovation (e.g., through community-based adaptation programs).

 9

10 Community-based adaptation includes a range of initiatives that put communities at the centre of planning
11 for adaptation, often led by communities themselves (Reid, 2016). Community-based adaptation is a
12 comprehensive and effective strategy to deliver resilience at a human scale (Trogal et al., 2018; Greenwalt et
13 al., 2020). Many community-based responses to climate impacts represent coping strategies developed
14 within households with a small effect on adaptation capacities beyond incremental improvements. Residents
15 adopt private coping strategies to reduce exposure to and the impacts of heat, floods, flash floods, landslides,
16 storms, and diseases on their lives (Hambati and Yengoh, 2018). These coping strategies include the
17 construction of physical protection against flooding, through reforestation, the construction of terraces, flood
18 diversion measures, and interventions to protect houses (such as raised doorsteps or use of sandbags and
19 adoption of building techniques for making homes resilient to storms and landslides), ventilation of houses,
20 urban agriculture, and redefinition of daily practices and livelihoods (Navarro et al., 2020; Malabayabas and
21 Baconguis, 2017; Apreda, 2016; de Andrade and Szlafsztein, 2020; Sahay, 2018; Bausch, Eakin and Lerner,
22 2018).

23

24 Individual coping strategies are generally ineffective in reducing extreme risks and they rarely address the
25 underlying structural causes of vulnerability (high confidence) (Sahay, 2018; Rözer et al., 2016; Jay et al.,
26 2021). Expending resources on private coping strategies in some cases may divert resources and capacity for
27 wider community adaptation efforts (de Andrade and Szlafsztein, 2020). However, individual coping
28 strategies can provide foundations for the implementation of collaborative action in communities building on
29 people's experiences, in ways which may have a longer-term, durable impact on developing resilience (high
30 confidence) (McEwen et al., 2018). Community-based adaptation can be effective at different scales,
31 whether this is to manage transboundary issues (Limthongsakul, Nitivattananon and Arifwidodo, 2017),
32 support the replication of local solutions (Daničre et al., 2016), increase the uptake of adaptation measures
33 (Liang et al., 2017), or inform the design of more effective policies for resilience (Berquist, Daniere and
34 Drummond, 2015; Odemerho, 2015). Community action may be mediated by NGOs or third sector
35 organizations who play a coordinating or enabling role, particularly where other local government
36 mechanisms are absent.

37

38 6.4.1.3 The role of the private sector in local adaptation

39

40 There is weak evidence of private sector involvement in urban adaptation (Pauw, 2015; Heurkens, 2016).
41 The absence of private sector investment in adaptation is particularly visible in rapidly urbanizing countries
42 (Nagendra et al., 2018). Business continuity describing private sector preparedness notes firms underestimate
43 the impacts of climate risks on their business models (Goldstein et al., 2019; Forino and von Meding, 2021;
44 Korber and McNaughton, 2017; Crick et al., 2018b). There is little research on how businesses can play a
45 leading role in urban adaptation (Klein et al., 2018). A global assessment of the private sector's role in urban
46 adaptation using data from 402 cities shows that most adaptation projects focus on the public sector and do
47 not address private sector concerns or local people's participation (Klein et al., 2018). Recorded private
48 sector action is recognized through partnerships and participation (Peterson and Hughes, 2017; Hughes and
49 Peterson, 2018). There are a few examples of studies of private sector-led adaptation action which adopts a
50 national focus (Crick et al., 2018a; Crick et al., 2018b). This lack of evidence contrasts with a well-
51 developed body of literature on private sector-led mitigation (Averchenkova et al., 2016).

52

53 Businesses have an essential role in urban adaptation actions, through the collective formulation of
54 adaptation strategies, through the provision of critical adaptive interventions, and through collaboration in
55 partnerships. Businesses in the property sector, such as real estate developers, are on the frontline of climate
56 change impacts but display differing attitudes towards climate adaptation. A study of property businesses in
57 cities in Australia (Taylor et al., 2012) showed that speeding up planning approval processes facilitated

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 1 adaptation actions, and joint private-public decision making was the preferred mode of governance for
 2 responding to climate concerns. Property businesses in cities in Sweden had a limited and reactive
 3 engagement in climate issues and resisted regulation (Storbjörk et al, 2018). Corporate, private sector
 4 interventions in urban risk reduction more broadly remain limited with a mix of public and private
 5 responsibility for planning, implementing, and maintaining adaptations in the built environment and yet,
 6 limited engagement of private sector actors in providing healthcare measures for heat prevention (medium
 7 confidence) (Mees, 2017).

 8

 9 There is little published literature documenting the heterogeneity of business and the private sector's
10 responses to climate impacts (Linnenluecke, Birt and Griffiths, 2015; Doh, Tashman and Benischke, 2019).
11 Firms have varying abilities to introduce climate adaptation measures related to staff availability, levels of
12 awareness, perceptions of responsibility, and duration of contracts (short-term projects implies less interest
13 in adaptation outcomes) (Shearer et al., 2016). The impact of COVID-19 has serious but uncertain
14 implications for both access to finances for sustainable development by low and middle income countries
15 and sub-national governments, and the possibility of stimulating mal-adaptive infrastructure and policy
16 responses (OECD, 2020; Sovacool, Del Rio and Griffiths, 2020). The response of businesses to disasters
17 influences the resilience in the communities in which they operate (McKnight and Linnenluecke, 2016;
18 Linnenluecke and McKnight, 2017). However, at the same time there is a growing literature that warns
19 against the conflict interests that businesses may have in their adaptation strategies. For example, real estate
20 responses to flooding have led to processes of climate gentrification, whereby lower income populations are
21 displaced towards higher risk areas which stablishes racialized and class-based patterns of inequality of
22 exposure to risk, with hard evidence rapidly growing specially in US cities (Keenan, Hill and Gumber,
23 2018a; Shokry, Connolly and Anguelovski, 2020; De Koning and Filatova, 2020; Aune, Gesch and Smith,
24 2020). Private-sector participation in adaptation solutions depend on having mechanisms to enable
25 transparency and open reporting on the nature of support and the solutions proposed. For example,
26 businesses adopting `community-centric' disaster management strategies can assist local recovery efforts by
27 protecting employment, provision of emergency supplies, and participation in reparations (McKnight and
28 Linnenluecke, 2016). Private sector actors engaged in community climate responses can play a role in
29 funding and managing programs that address public health and education concerns. The potential of
30 ecopreneurship, social enterprises, cooperatives and other sustainability-oriented business models
31 (Schaltegger, Hansen and Lüdeke-Freund, 2016; Lopes et al., 2020; Battaglia, Gragnani and Annesi, 2020)
32 for urban adaptation remains under-explored in the literature on urban climate governance.

33

34 The private sector also constitutes a key stakeholder group involved in collaborative processes to develop
35 adaptation strategies. The inclusion of private sector actors in deliberative policy-making processes in urban
36 adaptation can lead to higher procedural legitimacy levels, as witnessed in Rotterdam's case (Mees, Driessen
37 and Runhaar, 2014). Rotterdam has created an institutional environment that favours eco-innovation (Huang-
38 Lachmann and Lovett, 2016). The municipal government works directly with the private sector to enhance
39 protection against flooding constructing a marketing strategy around a `floating city' concept. A `floating
40 housing' market has expanded, with benefits for the local real estate and construction industries and
41 knowledge-exporting businesses that provide consultation expertise, delta technologies, and architectural
42 models. Nevertheless, these new trends raise new governance challenges to deliver adaptation.

43

44 There are obstacles associated with reconciling private sector interests with public priorities and justice
45 agendas in local climate programs. The involvement of the private sector in adaptation actions may lead to
46 the appropriation of land and natural resources, and to the exclusion of vulnerable populations (Anguelovski
47 et al., 2016; Rumbach, 2017; Scoppetta, 2016) (see also section 6.4.4.2). Navigating the inclusion of
48 businesses in urban planning processes requires local authorities to engage in ongoing negotiations, to reflect
49 on constantly shifting power balances, and to move delicately between the role of regulator and facilitator in
50 the process of defining and maintaining long-term objectives (Storbjörk, Hjerpe and Glaas, 2019b; Storbjörk,
51 Hjerpe and Glaas, 2019a).

52

53 6.4.1.4 Partnerships for adaptation

54

55 Multi-level governance remains an influential paradigm that recognizes government institutions' influence at
56 different scales and the diversification of actors intervening in public issues from the private sector and civil
57 society (robust evidence, high agreement). Establishing linkages between multiple organizations can help

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 1 deliver coordinated action. Multi-level governance includes mechanisms for multiple actors to engage in
 2 local adaptation strategies through collaborative processes of planning, learning, experimentation, capacity
 3 building, construction of coalitions, and communication channel (Barton, 2013; Jaglin, 2013; Reed et al.,
 4 2015; Restemeyer, van den Brink and Woltjer, 2017; Melica et al., 2018). Many of these studies directly
 5 focus on institutional arrangements that facilitate interaction between communities and civil society, experts,
 6 government representatives, firms, and international organizations. Box 6.5 demonstrates the decisive role
 7 that community activists can play in building resilience over long periods.

 8

 9 Institutional fragmentation reduces the capacity to deliver adaptation (Den Uyl and Russel, 2018) Multi-level
10 governance shows a commitment to tackling fragmented and complex policy issues through collaboration
11 between national governments and non-state actors, as explained in the 2030 Development Agenda,
12 especially SDG17 ("Revitalize the global partnership for sustainable development"). Multi-level governance
13 is particularly important to deliver adaptation at the metropolitan scale, that require coordinating actions
14 across different institutions in inter-municipal institutions (Lundqvist, 2016). Gaps in knowledge remain
15 regarding the effectiveness of multi-level governance actions in different contexts and the extent to which
16 multi-level governance strategies transfer the brunt of responsibility for adaptation action to less-resourced
17 local governments (Hale et al., 2021).

18

19 Public-private partnerships are increasingly relevant for collaborative development of urban adaptation
20 (Klein et al., 2018). Partnerships can deliver infrastructure, coordinate policy, and support learning. The
21 main limitation of partnerships is scale, as partnership action is usually limited to discrete projects or
22 objectives. Partnerships tend to be linked to reactive (rather than proactive) adaptation projects and the
23 deviation of objectives away from adaptation concerns (Harman, Taylor and Lane, 2015). Partnerships can
24 support capacity building in public and private organizations and facilitate networking efforts that extend
25 beyond the private sector to communities and NGOs (Bauer and Steurer, 2014; Castán Broto et al., 2015b).
26 Public actors can benefit from the private sector's innovation and implementation capacity, and businesses
27 can de-risk investments. Still, partnerships can also strengthen the ideologies of growth and managerialism
28 within the operations of the local government (Taylor et al., 2012). Reconciling divergent norms and routines
29 within public and private organizations remains one of the challenges to establishing successful public-
30 private partnerships for adaptation (Lund, 2018). Administrative and political culture influences the nature of
31 interactions between public and private sector actors in urban adaptation agendas (Bauer and Steurer, 2014)
32 with negative consequences such as the imposition of vertical chains of commands on horizontal
33 collaborations, and the need to formalize contractual relations (Klein and Juhola, 2018).

34

35 Local authorities are an important enabling actor that can guide the private sector and communities to take
36 responsibility for creating policy and regulatory environments that encourage private sector participation
37 aligned with the Sustainable Development Goals' equity and ecological sustainability principles (high
38 confidence). For example Frantzeskaki et al (2014) report a port relocation project in the Netherlands where
39 sustainability principles drove private sector participation. Klein et al (2017) cite examples from two cities -
40 Helsinki and Copenhagen - where local authorities have shifted adaptation responsibilities to private actors
41 through regulation and public problem ownership. In Mombasa, private companies provide green
42 infrastructure to match local government requirements, in what has frequently been cited as an example of
43 nature-based solutions (Kithiia and Dowling, 2010; Kitha and Lyth, 2011).

44

45

46 [START BOX 6.5 HERE]

47

48 Box 6.5: Building Water Resilience in Urban Areas through Community Action and Activism

49

50 In Bengaluru, India, communities have traditionally managed a network of water tanks of immense
51 ecological importance. However, in the last half-century, urban development has increasingly threatened this
52 blue network (Unnikrishnan and Nagendra, 2015). Today's Bengaluru depends on long-distance water
53 transfers that create political conflict and a dense network of private boreholes that are depleting the city's
54 water resources. The restoration of the existing community-managed water tanks network offers a more
55 sustainable and socially just alternative for managing water resources.

56

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 1 Unnikrishnan et al (2018) have documented how the colonial and postcolonial history of water management
 2 in Bengaluru shapes the water infrastructure and provision systems today. Water access inequalities can be
 3 traced to the patterns of spatial development developed by colonial policies. Records from the 6th century
 4 onwards show how city rulers invested in an interconnected, community-managed network of tanks and
 5 open wells, regularly recharged through harvested rainwater. The water system was changed at the end of the
 6 18th century, as first the colonial state, then the post-independence government of Karnataka took
 7 responsibility for water management. Ideas of modernist planning influenced the development of new water
 8 infrastructure and piped networks, including the first piped infrastructure, bringing water from sources 30km
 9 away, including the Hesaraghatta and then the TG Halli reservoirs. The old network of tanks gradually
10 deteriorated as tanks became disused, polluted, or built over. More prolonged and costly water transfers took
11 place in the post-colonial period, delivering water from the Cauvery river in a massive engineering project
12 with a high energetic cost and enmeshed in inter-state conflicts over water use (Castán Broto and Sudhira,
13 2019). Scarcity is still a problem in Bengaluru. The citizen response has been an activist movement to
14 reclaim the city's tanks, accompanied by a plea to reconsider current water uses within the city, including
15 actions to protect and rejuvenate water wells (Nagendra, 2016). Unnikrishnan et al (2018) document
16 different actions led by citizen-led collectives, including projects for lake rejuvenation, filtering technologies
17 to treat sewage, recovering the value of lakes through a share of photos and art projects, and involvement of
18 local knowledge in-tank restoration. Those efforts suggest an untapped potential to deliver adaptive green
19 spaces through the recovery of Bengaluru's tanks.

20

21 [END BOX 6.5 HERE].

22

23

24 6.4.1.5 Trans-national municipal networks

25

26 Since the late 1990s, transnational municipal networks (TMNs) have increased awareness of climate change
27 and served as a bridge for cities to access critical financial resources from private and philanthropic sources
28 (Rashidi and Patt, 2018; Fünfgeld, 2015). Recently, transnational municipal networks have taken on more
29 programmatic functions, working with cities to strategize, plan, and incrementally improve their organization
30 functions in the face of climate change. For example, the Rockefeller Foundation's 100 Resilient Cities
31 program (2014-2019) provided a two-year salary for a Chief Resilience Officer (CRO) to be situated in a
32 municipal authority to bridge silos, incentivize change, and develop development strategies for resilience
33 (Bellinson and Chu, 2019; Spaans and Waterhout, 2017). In these cases, external actors have enabled broad
34 organization change, resource mobilization pathways, and alternative forms of agenda-setting in cities (Chu,
35 2018a; Hakelberg, 2014) (see also case study 6.2, Semarang).

36

37 A range of transnational municipal networks (TMNs) also support and encourage cities and settlements to
38 plan and implement adaptation actions. ICLEI-Local Governments for Sustainability has developed
39 protocols and implemented projects for member cities. The C40 Climate Leadership Group has facilitated
40 the coordination of both local governments and business actors at a global scale (Gordon, 2020). Policy
41 coordination has been central to the signatories of the Covenant of Mayors (Domorenok et al., 2020). Such
42 networks can encourage: the sharing of information about appropriate practices between urban areas;
43 contribute to goal-setting; support experimentation and development of new policy instruments; enhance
44 stakeholder engagement; institutionalize climate agendas; and encourage policy integration across
45 governance levels and sectors (Bellinson and Chu, 2019; Busch, Bendlin and Fenton, 2018; Fünfgeld, 2015;
46 Busch, 2015; Papin, 2019; Rashidi and Patt, 2018). However, participation in TMNs is biased towards cities
47 in the global North (Bansard, Pattberg and Widerberg, 2017; Haupt and Coppola, 2019). A recent
48 comparative study of 337 cities found out that cities that participation in TNMs are more likely to take
49 adaptation action and that being part of multiple networks leads to higher levels of adaptation planning
50 (Heikkinen et al., 2020).

51

52 6.4.2 Institutional change to Deliver Adaptation in Cities, Settlements, and Infrastructure

53

54 The main barriers to urban climate adaptation, and strategies to address them, relate to institutional change
55 (high confidence) (see Table 6.7). Institutions include legislative and policy frameworks and guidelines
56 intended to direct the action of government, civil society and private sector organisations and extend into
57 informal and customary practices that shape individual behaviour. Many of the barriers that inhibit

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1 institutions acting in ways that can support action for inclusive and sustainable adaptation have historical
2 roots, grounded in complex political and social relations and can be reinforcing (Table 6.7). Overcoming
3 these barriers requires coordinating the activities of multiple actors who can facilitate institutional and

4 political change (Eisenack et al., 2014).

5

6

7 Table 6.7 Barriers to climate adaptation

   Examples of barriers to Institutional changes to Examples                                     Evidence

   climate adaptation        overcome those barriers

   Lack of financial         Strategic combination of In European countries, large cities (Aguiar et al.,

   resources                 municipal, regional and tend to fund their own adaptation, 2018)

                             national level funds        while smaller settlements depend on (Moser et al.,

                             Access to multiple          regional or national funding            2019)

                             financing mechanisms

   Lack of human resources   Development of formal       International cooperation               (UN-Habitat,
   and capacities            and informal                programmes for adaptation in urban      2016b)
                             partnerships, cooperative   areas in the Global South are most
                             agreements and inter-       likely to succeed if they can align
                             agency arrangements         their objectives with local priorities
                                                         and capacities

   Political commitment      Use of policy windows       In Germany, responses to flooding       (Gawel et al.,
   and willingness to act    and extreme events to       were strongly shaped by public          2018; Di Giulio et
                             generate interest and       perceptions of safety during the        al., 2018)
                             create lasting responses    electoral cycle, leading to
                                                         inadequate responses

   Uncertainty about future  Develop institutional       Power plant operators and the           (Eisenack, 2016)
   impacts and dynamic       arrangements that           federal state of Baden-Württemberg      (Thaler et al.,
   interactions              acknowledge and reduce      negotiated the minimum power            2019)
                             uncertainty                 plant concept
                             Facilitate the              ("Mindestkraftwerkskonzept",
                             development of bottom-      MPP), a contract to establish more
                             up initiatives that relate  predictable and workable
                             directly to the context of  procedures for curtailment in the
                             action                      event of severe heat waves

   Institutional             Evaluation of existing      In settlements in Languedoc,            (Therville et al.,
   fragmentation and         institutions to diagnose    France, decentralisation adds           2019)
   unclear responsibilities  miscoordination             complexity to the ongoing
                                                         challenges of population growth and
                             Creation of policy          climate change
                             networks that address
                             emerging
                             interdependences

   Legal issues and          Address the legal hurdles   Policy makers in the San Francisco      (Ekstrom and
   regulations               to create frameworks that   Bay Area, US reported that minor        Moser, 2014)
                             allow for experimental      changes could have a definitive
                             action                      influence in delivering regulatory      (Fatori and
                                                         changes to support adaptation action    Biesbroek, 2020)
                                                         In The Netherlands, a lack of
                                                         climate change adaptation policy for
                                                         cultural heritage hamper adaptation
                                                         of cultural heritage to current and
                                                         projected climate risks

   Competition of            Prioritization and          In European cities, for example,        (Aguiar et al.,
   adaptation with other     development of              urban planning is strongly              2018)
   policy agendas and        synergies across sectors    correlated with water management        (Sieber, Biesbroek
   polarisation              Mainstreaming               strategies                              and de Block,
                             adaptation into other                                               2018)
   Lack of data, knowledge   sectors                     In Scotland, Hungary and Portugal
   generation capacity, and  Mobilise multiple           local decision makers use HECC          (Lourenço et al.,
   knowledge exchange        strategies for the use of   scenarios, but most often as            2019)
                             climate information in      background data                         (Herrmann and
                             local decision-making                                               Guenther, 2017)

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                Involve a wide range of       Sharing knowledge alongside the      (Gotgelf, Roggero
                stakeholders- with            supply chain favours adaptation for  and Eisenack,
                different values and          both multinationals and SMEs         2020)
                knowledge- in decision                                             (Wamsler, 2017)
                making

1

2

3 Institutional change, is needed to open new options for inclusive and sustainable adaptation and to integrate
4 adaptation and mitigation (robust evidence, high agreement) (see also Section 6.3.5).

 5

 6 Institutional change refers to processes that aim to shift existing norms and practices within organizations to
 7 deliver more effective action for adaptation. Institutional change at the local level can be achieved with
 8 diverse strategies (Patterson, de Voogt and Sapiains, 2019). Table 6.7 illustrates various instruments that
 9 enable the institutionalisation of climate adaptation concerns into policy and planning. As Table 6.7 shows,
10 institutional change is often used as synonymous with mainstreaming. Both terms refer to the integration of
11 climate adaptation concerns into other areas of work and as part of practical routines and arguments (Chu,
12 Anguelovski and Carmin, 2016; Storbjörk and Uggla, 2015; Runhaar et al., 2018; Uittenbroek et al., 2014).
13 Early assessments understood mainstreaming as activities that integrate climate adaptation into long-range
14 and sectoral plans (Anguelovski and Carmin, 2011; Aylett, 2015). Since then, efforts to mainstream climate
15 adaptation have grown into agendas around the community and economic development (Ayers et al., 2014),
16 climate mitigation (Göpfert, Wamsler and Lang, 2019), spatial and infrastructure planning (Anguelovski,
17 Chu and Carmin, 2014), urban finance (Musah-Surugu et al., 2018; Keenan, Chu and Peterson, 2019), public
18 health (Araos et al., 2015), environmental management (Wamsler, 2015; Kabisch et al., 2016), and multi-
19 level decision-making (Ojea, 2015; Visseren-Hamakers, 2015). Such efforts require various degrees of
20 regulatory or programmatic action to integrate adaptation with other concerns (Wamsler and Pauleit, 2016).
21 However, institutional change has a broader remit than mainstreaming adaptation, as it may include, for
22 example, changing the organizations already dealing with climate adaptation and make them more effective
23 including changes in inputs, procedures, and options (Patterson, de Voogt and Sapiains, 2019).

24

25 6.4.2.1 Input-driven institutional change

26

27 Input-driven institutional change creates incentives to deliver adaptation action. An input view focuses on
28 the intrinsic capacities of a given organization. Input indicators are often referred to as political capital
29 (Rosenzweig and Solecki, 2018; Diederichs and Roberts, 2016), existing or endogenous resources (Moloney
30 and Fünfgeld, 2015; Wamsler and Brink, 2014), or local drivers for adaptation (Dilling et al., 2017).
31 Research conducted across two municipalities in Western Cape, South Africa, showed the importance of a
32 dedicated environmental champion, access to a knowledge base, the availability of resources, political
33 stability, and the presence of dense social networks (Pasquini et al., 2015). Research from In Săo Paulo,
34 Brazil, showed how intrinsic political capacities and contextual factors ­ such as the political ideology of
35 elected officials ­shaped opportunities for embedding adaptation into ongoing urban agendas (Di Giulio et
36 al., 2018).

37

38 Networks, interactions, and actor coalitions shape options for institutional change. Aylett (2015) noted the
39 importance of internal networks between municipal departments, including informal communication
40 channels, cultivating personal contacts and trust between the person or team responsible for climate planning
41 and staff within other local government agencies. Internal networks can facilitate the commitment of local
42 elected officials (Hughes, 2015), support higher municipal expenditures per capita, and foster perceptions
43 that climate adaptation is needed (Shi, Chu and Debats, 2015). Collective decision making can integrate
44 multiple types of information with moral concerns and provide key rationales that enable adaptation action
45 (Carlson and McCormick, 2015). In urban areas in Africa, research on internal networks has also
46 investigated how informal arrangements shape action possibilities (Satterthwaite et al., 2020). For example,
47 in Zimbabwe, informal, traditional, and civil society institutions are core arenas for issue discussion due to
48 lower public sector capacities (Mubaya and Mafongoya, 2017). In Durban, South Africa, local governments
49 rely considerably on shadow systems and informal spaces of information and knowledge exchange across
50 their operations to introduce and sustain new ideas (Leck and Roberts, 2015). In the Metropolitan Area of
51 Styria, Austria, informal cooperation has supported the development of rural-urban partnerships for the

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1 formulation of common goals (Oedl-Wieser et al., 2020). In Arkansas, US, informal governance structures
2 support planning to manage wildfires (Miller, Vos and Lindquist, 2017).

3

4 Cities can leverage input driven institutional change even without national support for climate change

5 adaptation or mitigation. For example, where cities have defined policy making and budget raising powers,
6 city level political leadership can support adaptation action going beyond national policy (Hamin, Gurran
7 and Emlinger, 2014; Shi, Chu and Debats, 2015; Carlson and McCormick, 2015). Examples include the

8 Surat Climate Change Trust in Surat, India (Chu, 2016a) and Initiative for Urban Climate Change and

 9 Environment in Semarang, Indonesia (Taylor and Lassa, 2015). In Saint Louis, Senegal, support from
10 national and state-level actors enabled local institutional change (Vedeld et al., 2016). Processual levers may
11 be also mobilized in situations of political instability (which disrupts patterns in champions and networks),
12 clientelism (which can cause environmental projects to be discontinued) (Pasquini et al., 2015), or in
13 contexts where there are high political and socioeconomic inequalities (Harris, Chu and Ziervogel, 2018;
14 Chu, Anguelovski and Carmin, 2016).

15

16 6.4.2.2 Output-driven institutional change

17

18 Output-driven institutional change is shaped by organisational products such as strategies, plans, policies,
19 and evaluative metrics (Patterson and Huitema, 2019; Bellinson and Chu, 2019) (See table 6.8). There are
20 numerous examples of institutional change through planning outcomes. For example, Manizales, Colombia

21 has included climate adaptation into long-established environmental policy (Biomanizales) and a local

22 environmental action plan (Bioplan), which follows on from a long coherent trajectory of climate change
23 policy (Hardoy and Velásquez Barrero, 2014). A significant number of North American cities have
24 integrated adaptation into long-range plans, while fewer cities integrate adaptation in sustainable

25 development plans or sectoral plans (Aylett, 2015). Canadian cities are more likely to have a plan

26 specifically focused on adaptation than having adaptation integrated into municipal long-range planning
27 (Aylett, 2015). In the European Union, adaptation plans depended on national climate legislation or, in fewer
28 cases, the influence of an international climate network (Reckien et al., 2018b). A comparative report from
29 the Covenant of Mayors, however, suggests that the adaptation pillar needs development to demonstrate the
30 effectiveness of adaptation responses and their integration with mitigation goals (Bertoldi et al., 2020).
31 Municipalities in Sweden have been called `pre-reactive' because adequate strategic guidelines are in place
32 to frame the accessibility, aesthetics, and adaptability of waterfront developments (Storbjörk and Uggla,
33 2015). Some Asian cities also report high output effectiveness, where they are more likely to indicate senior

34 local government officials' performance management contracts, the budgeting procedures of local
35 government agencies, and the procedures that local government agencies use for budgeting infrastructure
36 spending (Aylett, 2015). Despite this evidence, there is a gap in understanding the general trends of planning
37 and institutional change in Africa, Asia, East Europe and the Middle East.

38

39

40 Table 6.8 Examples of institutional and policy instruments to enable adaptation

    Objective    Type of              Description            Examples               Assessment
                 instrument

    Policy       Information          A diverse range of     Urban-LEDS II Information instruments tend to be
                 Instruments          activities such as
                                      training, research     Capacity Building low-cost and low-risk options, but
                                      and development,
                                      awareness              Workshop for cities their impact is unpredictable and the
                                      campaigns to
                                      produce and share      in Laos arranged effects may be uneven (Henstra,
                                      information
                                                             for local              2016). In the example of the

                                                             government by          workshops in Laos (UN-Habitat,

                                                             ICLEI Southeast 2019), the result was to map

                                                             Asia Secretariat vulnerable sectors and build

                                                             and UN-Habitat capacity for mainstreaming

                                                             (UN-Habitat, 2019)

                 Voluntary            Practices such as      PUB, Singapore's A problem with voluntary
                 Instruments          codes, labeling,       National Water instruments is that implementation
                                      management             Agency's Voluntary varies. Uptake is likely to be more
                                      standards or audits,   Water Efficiency common among organizations self-
                                      voluntarily, that can  Labelling Scheme identifying as `champions' and less
                                                             (Voluntary WELS) effective among other actors to

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                                  provide incentives    (Tortajada and      bring about far-reaching change
                                  for adaptation        Joshi, 2013)        (Haug et al., 2010)
                                  Taxes or subsidies
             Economic             can be used to        US Office for       Economic incentives can be
             Instruments          promote adaptive      Coastal             effective as they "engage local
                                  activities
             Regulatory                                 Management          stakeholders and provide price
             Instruments          These include a
                                  range of mandatory    NOAA Coastal        signals that stimulate individual
             Visioning            requirements          Resilience Grants   adaptation" (Filatova, 2014).
                                  through controls,     Program (NOOA,      However, uptake of incentives may
             Baseline             bans, quotas,         2019)               be low (Sadink, 2013; Henstra,
             studies              licensing, standards                      2016) and resource intensiveness
                                  often applied when
             Development          a specific outcome                        and potential regressive effects
             priorities           is required
                                                                            (equity impacts) must be considered
             Profiles             Events that bring
                                  together different                        (Henstra, 2016).
                                  stakeholders to
                                  produce a city        Building codes to Regulatory instruments can be
                                  vision                enhance structural effective in changing and

                                  Focus on              stability for storm institutionalizing adaptation
                                  understanding the
                                  current conditions    resilience in       behaviours (Nilsson, Gerger
                                  in a neighbourhood
                                  or city from an       Moore, Oklahoma Swartling and Eckerberg, 2012;
                                  interdisciplinary     (US) (Ramseyer, Henstra, 2016), but outcomes
                                  perspective
                                                        Holliday and        depend on the strength of
                                  Specific methods to
                                  ensure an open        Floyd, 2016)        implementation (e.g. monitoring,
                                  definition of
                                  multiple priorities                       transparency, mechanisms for
                                  and contrasting                           accountability)
                                  values that will
Process                           inform the planning   Rotterdam           There may be challenges in
Planning                          process               Resilient City      translating complex climate science

                                  Develop a common      participatory       into understandable and meaningful
                                  understanding of
                                  how different         processes to create forms (Sheppard et al., 2011) and
                                  sectors interact
                                  with adaptation and   resilience strategies creating inclusive processes that
                                  the governance
                                  capacity              (Resilient          allow for co-creation of visions, for

                                                        Rotterdam, 2016) example, by involving new digital

                                                                            platforms (Baibarac and Petrescu,

                                                                            2019)

                                                        Flood Risks,        Baseline studies can be mobilized to
                                                        Climate             track the progress of adaptation
                                                        Change Impacts      actions in multiple sectors over
                                                        and Adaptation      time. In the example of the study in
                                                        Benefits            Mumbai (Hallegatte, Ranger and
                                                        in Mumbai, an       Bhattacharya, 2010), the analysis
                                                        OECD assessment     includes different climate scenarios
                                                        study (Hallegatte,  and quantification of how
                                                        Ranger and          adaptation could reduce economic

                                                        Bhattacharya,       loss

                                                        2010)

                                                        Participatory       Participatory planning can help
                                                        housing upgrading   navigate which action to take to
                                                        through the Baan    build resilience and, at the same
                                                        Mankong Program     time address prioritized social

                                                        in Bangkok          concerns (Cloutier et al., 2015). As

                                                        (Thailand)          with all participatory processes,

                                                        (Berquist, Daniere  issues of recognition,
                                                        and Drummond,       access/inclusion, and potential
                                                        2015)               capture of the process by actors in
                                                                            power must be considered

                                                        New York City As with baseline studies, the

                                                        Panel on Climate    development of profiles can inform
                                                        Change 2019         plans for adaptation action, which
                                                        Report (Nycpcc,     considers social priorities and

                                                        2019)               synergies across various sectors.

                                                                            Multiple forms of knowledge
                                                                            should be considered in the
                                                                            development of profiles (Codjoe,
                                                                            Owusu and Burkett, 2014)

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                Risk                 This includes a       Climate risk        Risk assessments can be a useful
                assessment           range of              assessment for      starting point for adaptation.
                                     instruments to        Buenos Aires,       However, assessments do not
                                     evaluate the impact   conducted by the    directly prescribe adaptation options
                                     of risk               World Bank          but must be seen as the basis for
                                                           (Mehrota et al.,    debate (Yuen, Jovicich and Preston,
                                                           2009)               2013). A common challenge is a
                                                                               lack of data at the city level
                                                                               (Maragno, Dalla Fontana and
                                                                               Musco, 2020; Cloutier et al., 2015)

                Impact               Tools such as         Economic Impact     Embedding climate risks into
                assessment           Strategic Impact      Assessment          impact assessment tools (either
                tools                Assessment or         of Climate Change   mandatory or voluntary) builds
                                     Sustainability        in Key              resilience by integrating climate
                                     Assessment provide    Sectors in Nepal    objectives into plans and specific
                                     a means to assess     (Government of      projects (Richardson and Otero,
                                     the impact of         Nepal, 2014)        2012), and they are seen as a
                                     specific policies                         legitimate tool in many contexts
                                     and programmes                            (Runhaar, 2016)
                                     concerning
                                     adaptive capacity

                Monitoring           Systems to take       Climate Change      Monitoring systems are essential to
                systems and          measurements at       Adaptation          make sure that formal objectives are
                indicators           regular intervals to  Indicators for      met. However, many urban climate
                                     specify progress      London (London      adaptations do not have monitoring
                                     against objectives    climate change      and evaluation components
                                     and revise the        partnership, 2018)  (Woodruff and Stults, 2016) and
                                     planning process                          there is no standard set of indicators
                                                                               to monitor adaptation or resilience
                                                                               (Brown, Shaker and Das, 2018;
                                                                               Ford and Berrang-Ford, 2016)

   Management Budgets and            Methods for the       Helsinki            As with monitoring, budgets and
                      audits         periodic revision of
                                     adaptation plans      Metropolitan area audits can be incorporated into the
                                     and policies
                                                           climate change      adaptation planning process to

                                                           adaptation          ensure reflexivity and

                                                           monitoring strategy accountability. Low levels of

                                                           (HSY, 2018)         implementation and monitoring of

                                                                               adaptation plans suggest that the

                                                                               uptake may be low (although the

                                                                               evidence is limited)

1

 2

 3 Institutional change processes are complex, contested, and sporadic (Patterson, de Voogt and Sapiains,
 4 2019). Such processes are often inhibited by unclear planning mandates, conflicting development priorities,
 5 lack of leadership, and resource and capacity shortfalls (Anguelovski et al 2014). There is no one size fits all
 6 approach to institutional change, which works in situ, and benefits from clearly defined plans and an
 7 incremental approach to revising new elements and addressing gaps or failures (Beunen et al, 2017). A
 8 longitudinal view of institutional change allows for assessing actors and dynamics involved in integrating
 9 adaptation into the sectoral agendas or governance arrangements mentioned above. (Patterson and Huitema,
10 2019).

11

12 6.4.3 Solution spaces to address the `policy action gap'

13

14 A policy action gap arises when administrative, communication, financial and other organisational blockages
15 and inertia interrupt implementation of policy, the intent of political leadership and delivery of adaptation
16 interventions on the ground (Ampaire et al., 2017; Bell, 2018; Shi, 2019). Political and policy confidence are
17 key enabling conditions for adaptation decision-making. As the AR5 already acknowledged, political
18 inaction can arise where there is low confidence that adaptation actions can deliver a safer future for all
19 (Chan et al., 2015a). For example, in some administrative jurisdictions (most of them local governments),
20 calls by social movements for the adoption of Climate Emergency Declarations were addressed, however,

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 1 practical outcomes in terms of adaptation have been limited, and may have foreclosed other future local
 2 actions (Nissen et al., 2020; Ruiz Campillo, Castan Broto and Westman, 2020), and raised concerns about
 3 maladaptation (Long and Rice, 2019). Political inaction for climate justice is particularly visible in contexts
 4 of informality (Ziervogel, 2020). Studies of city and local authority decision making in South America (Di
 5 Giulio et al., 2019), Asia (Araos et al., 2017) and Europe (Lesnikowski et al., 2021) indicate where there is
 6 insufficient political will (that is lack of prioritization of the issue, and inadequate allocation of resources
 7 including staffing and finance) and lack of inclusive, coordinated leadership, it can be difficult to overcome
 8 inaction, generating a policy action gap.

 9

10 Multiple actors contribute to deliver climate change adaptation (Chan et al., 2015a; Bäckstrand et al., 2017).
11 There are also multiple scales of action, from the provision of local services to large infrastructures of
12 national or even international significance. Figure 6.5 provides an insight into the challenges that shape the
13 policy action gap and a range of strategies that can help bridge policy action gaps. Effective adaptation
14 governance will depend on the compound impact of the actions of multiple agents operating at different
15 scales (medium confidence, medium agreement) (Di Giulio et al., 2019; Hale et al., 2021; Zwierzchowska et
16 al., 2019).

17

18

19

20 Figure 6.5 Solution spaces for the policy action gap. The categories in the outer circle represent the tension that shape
21 the policy action gap. On the one hand, there is a tension between the need to deliver action at scale (Multi-level) and
22 the need to mobilise the capacities in a given place (Place-bound). On the other hand, there is a tension between the
23 need to facilitate collaborations among multiple actors (Multi-actor) and the fundamental impact that leadership can
24 have in actor-led initiatives (Actor-led). These two tensions interact creating different possibilities for transformative
25 adaptation. The inner ring represents different areas of intervention that configure the solution space to tackle the policy
26 action gap, and that bridge these two tensions.

27

28

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 1 6.4.3.1 Delivers on the needs of the most vulnerable

 2

 3 Success in urban adaptation is most often understood as requiring measurable outcomes and evaluation (see
 4 also section 6.4.6). However, many adaptation outcomes are not measurable (medium evidence , medium
 5 agreement) (Béné et al., 2018). Adaptation action solely focused on action tends to ignore areas of action in
 6 the city for which there is no existing data even though they may play an essential role in shaping resilience
 7 and its limits. Informal settlements and informal economies which are integral in managing urban resources
 8 for effective climate adaptation are not routinely included in formal urban and national monitoring, including
 9 through tax receipts --are (Guibrunet and Castán Broto, 2016). The resulting understanding and monitoring
10 of city needs, capacities and actions that feed into policy is incomplete. The innovation as well as particular
11 concerns and capacities of the informal sector, which is often highly gendered are not always measured
12 (Brown and McGranahan, 2016). An emphasis on measurable adaptation outcomes may lead to prioritizing
13 techno-economic measures to adaptation at the local level. Technocratic approaches to environmental policy
14 continue to shape local sustainability politics (Bulkeley, 2015a). The deployment of such technocratic
15 approaches at the local scale is detrimental for democratic and collaborative practices (Metzger and
16 Lindblad, 2020). For example, China has received praise in terms of delivering urban policies that put
17 climate change at its core, thus suggesting its role providing leadership in climate change debates (Liu et al.,
18 2014; Wang and He, 2015; Fu and Zhang, 2017). However, a detailed analysis of case studies of sustainable
19 development in China's cities demonstrates that processes of planning only take into account certain groups
20 and interests (Westman and Broto, 2018). Urban sustainability policy may, as a result, fail to deliver
21 collaborative social and environmental objectives, and this is maladaptive in the terms of Climate Resilient
22 Development.

23

24 6.4.3.2 Moves from mainstreaming to transformative adaptation

25

26 Two forms of mainstreaming are usually found in urban policy: incorporating climate adaptation into
27 different sectors or incorporating climate adaptation in holistic sustainability or resilience plans, linking
28 climate adaptation objectives with other social and development objectives (Reckien et al., 2019; Fainstein,
29 2018). The integration of climate adaptation in local policies in cities and settlements has often been seen as
30 maintaining business-as-usual and not always aligned with transformative efforts to address structural drivers
31 of vulnerability (high confidence). For example, mainstream actions that seek to advance other development
32 objectives, as explained above, may reduce adaptation to `low-hanging fruits,' which may maintain business-
33 as-usual practices without any fundamental transformation of the social, institutional and economic systems
34 that drive vulnerabilities (Aylett, 2014). However, as explained above, mainstreaming can also generate
35 wider processes of institutional change (section 6.4.2). Mainstream strategies may help to demonstrate how
36 policy and frameworks can produce practical outcomes on the ground (Biesbroek and Delaney, 2020).
37 However, previous experiences in other sectors, such as gender mainstreaming, have shown the limitations
38 of the mainstreaming approach, particularly in terms of addressing the structural drivers of inequality and
39 vulnerability, and in achieving justice for those who suffer most (Moser, 2017). Local governments, in
40 particular, can link mainstreaming efforts with specific strategies that support justice in adaptation, including
41 redistribution efforts to address vulnerabilities (see section 6.3.2), representation in local institution and
42 deliberative processes, and recognition of the conditions for self-realization, including personal and
43 collective safety (Agyeman et al., 2016; Castán Broto and Westman, 2017; Castán Broto and Westman,
44 2019; Hess and McKane, 2021).

45

46 6.4.3.3 Facilitates coordination across separate actors and interests

47

48 Coordination of adaptation policy goals cuts across cities to integrate cities into international processes of
49 climate policy formulation; coordination in cities produces effective collective outcomes, cementation of
50 common standards and methodologies for climate action (e.g., emission inventories) (high agreement,
51 medium evidence) (Gordon and Johnson, 2017; Hsu and Rauber, 2021). A collective global response has
52 become a significant concern in international climate policy (Chan et al., 2015a). The UNFCCC has adopted
53 a role as an orchestrator including providing framework for city governments (Bäckstrand and Kuyper,
54 2017). Within cities, coordination can arise from active programming; for example, in Rotterdam and New
55 York City local authorities adopted long-term objectives and conditions for action, bringing together a
56 multiplicity of actors across sectors to orient contributions, share knowledge, and coordinate actions
57 (Hölscher et al., 2019). Where national politics is supportive, coordination between city and national

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 1 government is an asset (Chan and Amling, 2019; Inch, 2019). The use of social media and digital
 2 mechanisms for coordination with public interest is ambiguous: in China, Weibo has facilitated an expansion
 3 of public engagement, although it remains top down and dominated by a few individuals (Yang and Stoddart,
 4 2021). The pilot project #OurChangingClimate is one example of engaging youth with an understanding of
 5 their communities and their resilience or vulnerability to climate change (Napawan, Simpson and Snyder,
 6 2017).

 7

 8 6.4.3.4 Enables the coproduction of adaptation strategies with citizens

 9

10 Co-production can advance urban sustainability and social justice in cities and settlements to provide
11 infrastructure adapted to the human scale, and advancing SDGs (medium confidence) (McGranahan, 2015;
12 McGranahan and Mitlin, 2016; Chowdhury, Jahan and Rahman, 2017; Moretto and Ranzato, 2017; Nastiti et
13 al., 2017). Co-production involves the active involvement of citizens and citizens' organization in iterative
14 public service planning and delivery and has become increasingly central in climate change responses
15 alongside other bottom-up, community-led strategies (Bremer et al., 2019; Vasconcelos, Santos and Pacheco,
16 2013).

17

18 Coproduction builds on public participation that brings together diverse sets of citizen interests, values, and
19 ideas to inform change and solve problems relating to a collective adaptation challenge (Archer et al., 2014;
20 Bisaro, Roggero and Villamayor-Tomas, 2018; Sarzynski, 2015) and is increasingly important in
21 environmental policy more widely (McGranahan, 2015; Moretto and Ranzato, 2017). For example, in three
22 cities across the Czech Republic, stakeholder participation exercises were used to prioritize climate change
23 risks, provide impetus and opportunity for knowledge co-production, and support adaptation planning
24 (Krkoska Lorencová et al., 2018). In municipalities in Malaysia, stakeholders and citizens are active in the
25 adaptation policy cycle (Palermo and Hernandez, 2020). In Quebec, Canada, citizens collaborated with the
26 municipal authority to bring together climate science and `ordinary' urban management and design solutions
27 (Cloutier et al., 2015). Service coproduction enables integrating multiple actors in the management and
28 delivery of public services (Pestoff and Brandsen, 2013; Pestoff, Brandsen and Verschuere, 2013). Civil
29 society-driven, co-productive approaches can pioneer new forms of institutional relations and practices
30 filling gaps where the public sector is absent or retreating (Frantzeskaki et al., 2016).

31

32 A coproduction approach to climate change governance addresses the increasing public interest on climate
33 change (Davies, Broto and Hügel, 2021). Youth movements such as Forum for Future have joined forces
34 with other environmental and Indigenous organisations to lobby governments and institutions to action
35 (Kenis, 2021; Fisher and Nasrin, 2021; Davies and Hügel, 2021; Hayward, 2021). These movements have
36 built momentum moving local governments and other institutions to declare a climate emergency and have
37 supported the creation of new forums where climate change can be addressed collectively, such as citizens'
38 assemblies. In the UK, for example, initial scepticism has led to the proliferation of citizen-centric Climate
39 Assemblies at the local level (Sandover, Moseley and Devine-Wright, 2021).

40

41 Cooperative governance models provide insights for designing forms of participatory and collaborative
42 planning through which communities and state actors can identify concrete actions and resources to improve
43 services and mitigate structural vulnerabilities to disasters (Castán Broto et al., 2015b). Experiences of co-
44 production of sanitation services show how co-production may improve outcomes while at the same time
45 opening up avenues for grassroots organizations to claim political influence (McGranahan and Mitlin, 2016).
46 Coproduction may change institutions in response to external interventions (Das, 2016). Although there are
47 drawbacks in terms of the extent to which coproduction can be used to legitimize unfair interventions within
48 a given context, coproduction may also be a tool for improving the accountability of dominant groups to
49 vulnerable sectors of the population (Nastiti et al., 2017). There are limitations to coproduction. The city of
50 Barcelona, Spain used coproduction methodologies to develop the Barcelona Climate Plan. However, policy
51 makers and civil servants were reluctant to use lay knowledge from participants and political deadlines
52 constrained the time dedicated to deliberation (Satorras et al., 2020).

53

54 6.4.3.5 Addresses inequalities through intersectional perspectives

55

56 Inclusive and sustainable adaptation can address the causes of systemic vulnerability (medium evidence,
57 high agreement). This points to the fundamental requirements of adaptation action in line with the Universal

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 1 Declaration of Human Rights. Climate justice theories draw on the environmental justice movement
 2 experiences at the local level (Bickerstaff, 2012; Bickerstaff, Walker and Bulkeley, 2013; Perez et al., 2015;
 3 Hall, Hards and Bulkeley, 2013). Slogans such as `leave no one behind' embedded in international policy for
 4 cities and settlements recognize the connection between systems of oppression and exclusion that reproduce
 5 and perpetuate urban inequality and the delivery of urban services and security (Kabeer, 2016; Stuart and
 6 Woodroffe, 2016).

 7

 8 Intersectional strategies of action seek to consider the multiple forms of structural oppression experienced at
 9 the local level (Grunenfelder and Schurr, 2015) and, in the context of adaptation, explain how they produce
10 or exacerbate vulnerabilities. For example, intersectionality ties with the idea of how multiple deprivations
11 shape access to services (from sanitation to health and education) and the exposition to environmental risks
12 (Sicotte, 2014; Lau and Scales, 2016; Van Aelst and Holvoet, 2016; Lievanos and Horne, 2017; Raza, 2017;
13 Yon and Nadimpalli, 2017; European Environment Agency, 2020) (see Box 6.6 on the participation of
14 women in local decision making bodies). For example, fisherwomen in the western coast of India rely on a
15 complex arrangement of relationships around categories of class, caste, and gender that shapes their
16 possibilities to draw political resources to maintain their livelihoods, and hence, influence the dynamics of
17 transformation (Thara, 2016). Intersectionality is central to build resilience across communities, rather than
18 in particular areas (Khosla and Masaud, 2010; Reckien et al., 2017). Including intersectionality deliberately
19 in partnerships with communities can empower socially excluded groups and highlight justice issues while
20 aligning agendas with local development priorities (Castán Broto et al., 2015a). Despite the high confidence
21 on the growing importance of intersectionality concerns in the delivery of just environmental policies, there
22 is limited evidence of its explicit inclusion in adaptation policies.

23

24

25 [START BOX 6.6 HERE]

26

27 Box 6.6: Invisible Women: Lack of Women's Participation in Urban Authorities

28

29 Women are under-represented internationally in governance structures (Prihatini, 2019; Gonzalez-Eiras and
30 Sanz, 2018; Rashkova and Zankina, 2017; Koyuncu and Sumbas). This situation is reflected in urban
31 authorities where participation by those who identify as women is low (Williams, Devika and Aandahl,
32 2015; Kivoi, 2014). Das (2014) reports deep-rooted economic inequalities are barriers for women's
33 participation in Indore, India, and that women's collective empowerment could increase their bargaining
34 power within households as well as in the community and state. Kivoi (2014) draws a similar conclusion
35 presenting experience from Kenya. The big question is how to make women more visible in the urban
36 governance process?

37

38 What are the barriers women face and how do we increase their participation so that urban governance
39 become more inclusive? Escalante and Valdivia (2015) show the participatory tools that can be used at
40 different stages of planning for women's empowerment using bottom up planning models. Using these tools
41 makes planning process more inclusive. Araujo & Tejedo-Romero (2016) show from Spanish local councils
42 that women's political representation in municipalities has a positive influence on the level of transparency,
43 increasing information transparency and reducing information asymmetry. In Myanmar (Minoletti, 2014)
44 increased levels of women's participation in urban authorities helped to improve the quality of governance
45 such as reducing corruption and conflicts and improving service delivery.

46

47 [END BOX 6.6 HERE]

48

49

50 People traditionally excluded from climate change governance, such as children, are also more likely to have
51 their needs and priorities considered in urban planning for adaptation where there are national advocacy
52 bodies, for example, Commissions for Future, or Children's commissions (Nordström and Wales, 2019;
53 Watts et al., 2019; Hayward, 2021). An emphasis on procedural justice in decision making has potential to
54 produce transformational outcomes where these are defined as significantly reducing inequality (Holland,
55 2017). In this light emerging evidence suggests transformative adaptation is more likely to occur if people
56 have the agency to influence decisions and enact change (Archer and Dodman, 2015). Cities are also more
57 likely to build and develop infrastructure that serves the needs of disadvantaged groups, when urban climate

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 1 governance encourages wider community participation and inclusion (Ziervogel, 2019a; Hölscher et al.,
 2 2019; Anguelovski et al., 2016). This can help to stimulate innovation, shift power relations and address
 3 diverse needs (Martel and Sutherland, 2019; Chu, Schenk and Patterson, 2018). Experiments in including
 4 marginalized groups in adaptation planning are starting to emerge in places such as Quito (Ecuador), Lima
 5 (Peru), Manizales (Colombia) and Surat (India), where disadvantaged youth, informal settlers, and other
 6 vulnerable communities are included in discussions of short-/long-term adaptation needs and fair distribution
 7 of adaptation resources (Chu, Anguelovski and Carmin, 2016; Sara, Pfeffer and Baud, 2017; Hardoy and
 8 Velásquez Barrero, 2014). These processes can also support citizens to manage risks as they encounter them
 9 in their everyday life (Ziervogel et al., 2017).

10

11 In order to respond to urban injustices, attention needs to be paid to both the local level and to broader
12 system-wide governance issues (that are unpacked further in section 6.4). At the local level it is important to
13 understand who is most vulnerable to climate risk, which is likely to be related to class, race, gender, ability
14 and age (Wilby and Keenan, 2012; Ranganathan and Bratman, 2019; Thomas, Cretney and Hayward, 2019).
15 Factors such as age and levels of ability, as well as those pursuing outdoor livelihoods, have a direct link to
16 higher vulnerability to heat stress (Conry et al., 2015). In least developed countries, less than 60% of the
17 urban population have access to piped water which impacts on health and well-being, and emphasizes the
18 importance of alternative resources for these households (World Health Organization, Nations and Fund,
19 2017).

20

21 6.4.3.6 Supports visionary and imaginative design

22

23 The failure to deliver inclusive and sustainable adaptation contributes to a collective inability to mobilize the
24 power of creative community vision (medium evidence, high agreement). Urban design plays a central role
25 to support creative adaptation strategies (Box 6.7). Much adaptation action repeats previous experiences.
26 However, the potential for building resilience to deliver adaptation- especially transformative adaptation-
27 requires an articulation of collective visions of the future and the imagination of new or alternative urban
28 futures (Glaas et al., 2018) including through design and deliberate engagement with cultural artefacts,
29 technologies, and performances (Jordan, 2020). Social movements can be powerful sources of such
30 alternative visions of the future, as exemplified by recent Youth Climate Strikes and Extinction Rebellion
31 (limited evidence, medium agreement). Community protest including Youth Climate Strikes have influenced
32 urban climate policy agendas including the declaration of climate emergency in municipalities worldwide,
33 fostering a new debate on climate change, although their impact on local policy is ambiguous (Davidson et
34 al., 2020; Thomas, Cretney and Hayward, 2019; Prendergast et al., 2021; Ruiz Campillo, Castan Broto and
35 Westman, 2020). Social movements on climate mitigation, such as the Transition Movement and Transition
36 Towns (Feola and Nunes, 2014), and School strikes may serve as an example for mobilizations more
37 specifically about climate adaptation and the way new, networked, grassroots citizen activism and
38 community organizations can encourage urban institutional change (Gunningham, 2019; Jordan et al., 2018;
39 Wahlström et al., 2019). Other strategies such as cultural production and exhibitions may also have an
40 impact (Stripple, Nikoleris and Hildingsson, 2021).

41

42

43 [START BOX 6.7 HERE]

44

45 Box 6.7: The Role of Urban Design in Local Adaptation

46

47 Since AR5 there has been a growing literature about the role of urban design, creating new opportunities for
48 both incremental and transformative adaptive responses to climate change (medium evidence, high
49 agreement). For example some of these creative design approaches compliment and extend regulatory and
50 land use planning approaches such as form-based codes and established certifications like LEED-ND
51 (Leadership in Energy and Environmental Design ­ Neighbourhood Design) (Garde, 2018; Garde and Hoff,
52 2017) and the USA's Sustainable Sites Initiative (SITES) (Valente, 2014). Emphasis on sufficiency has also
53 influenced urban design, for example, with the mobilization of `doughnut' economics that emphasize both a
54 social foundation and an environmental ceiling, for example Amsterdam (Raworth, 2017). However, such
55 cases are rare, substantial public investment is often required (high confidence, high agreement) (see also
56 section 6.4.7 on finance and insurance). Other approaches underscore innovation and creativity, at the
57 essence of which are context-specific interventions that draw on a compendium of urban design principles

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 1 such as: indeterminacy (to accommodate climate uncertainty), polyvalency and diversity, and harmony with
 2 nature (Dhar and Khirfan, 2017a). Creative interventions include the daylighting of buried streams to create
 3 climate adaptive public realms (Khirfan et al., 2020; Khirfan, Mohtat and Peck, 2020). For example, the
 4 demolition of a major expressway and the restoration of the Cheonggyecheon stream reorganised downtown
 5 Seoul, South Korea and significantly contributed to climate change adaptation through stormwater
 6 management and reducing the urban heat island effect (Kim and Jung, 2019). Biomimicry and ecological
 7 infrastructure are design features that governance bodies can use to reshape space and contribute to place
 8 making (Santos Nouri and Costa, 2017; Prior et al., 2018). For example, urban metabolism and local
 9 ecological knowledge has constituted the essence of urban design interventions in the Island of Tobago in
10 ways that capitalize on the contiguous relationship between ecosystems (e.g., the mangrove forest) and
11 human actions (rainwater harvesting and grey water management) (Khirfan and Zhang, 2016). While lack of
12 funding, or design capacity, restrictive planning regulations, inequality and competing urban agendas can
13 create barriers for the implementation of creative design solutions, transition architecture movements are also
14 driving local urban adaptation experiments and exploring ways local learning can be scaled up (Tubridy,
15 2020; Irwin, 2019).

16

17 [END BOX 6.7 HERE]

18

19

20 6.4.4 Limits of Adaptation Capacity at the Institutional Level

21

22 In delivering adaptation in cities, settlements, and infrastructure, however, there is a need to understand and
23 measure the adaptive capacity and limits to manage future risks in communities, institutions, and
24 organizations (Filho et al., 2019). However efforts to track urban adaptation lack consistent methods, metrics
25 and data gathering (Olazabal et al., 2019b). The scale of complex, cascading challenges, limited finance and
26 governance capacity combined with the impacts of growing social inequality and sustainable development
27 priorities can result in both soft and hard limits on cities government's capacity to adapt to climate change
28 (Chanza, 2018; Sanchez Rodriguez, Ürge-Vorsatz and Barau, 2018; Lehmann et al., 2015; Di Giulio et al.,
29 2018). Hard limits to adaptation are identified when it is unfeasible to avoid severe risks while soft limits
30 exist when technological and socioeconomic options are not immediately deployable (Pachauri, Meyer and
31 Barros, 2014). In urban contexts soft limits may become hard limits when large numbers of people are
32 unable to avoid severe climate related risks of loss and damage (Mechler et al., 2020). Climate change-
33 related loss and damage that are intangible also require more caution in assessment processes (Roberts and
34 Pelling, 2018; Andrei et al., 2015; Barnett et al., 2016; Thomas and Benjamin, 2018). Incorporating
35 Indigenous knowledge can identify people-oriented and place-specific scenarios leading to developing urban
36 adaptation policies that foster identity, dignity, self-determination, and better collective decision-
37 making/capacity to act (McShane, 2017; Preston, 2017) and are sensitive to the local context and limits of
38 community adaptation (Makondo and Thomas, 2018).

39

40 Urban transformations represent forms of adaptation that challenge the principles in which a society is
41 established (Pelling, O'Brien and Matyas, 2015) and can be deployed to go beyond the existing limits of
42 development justice and climate change adaptation capacity. While not all adaptation will be transformative,
43 transformative capacities support both ongoing adaptation efforts and the broader systemic change processes
44 that align adaptation efforts with decarbonization requirements and the SDGs' delivery. `Urban
45 transformative capacity' focuses on understanding what elements of a system to respond to external
46 changing conditions in a manner that transforms the system towards a more sustainable state (Ziervogel,
47 Cowen and Ziniades, 2016). The capacities required to deliver adaptation action in cities and settlements are
48 `transformative capacities,' because they move away from thinking of adaptation as an adjustment to a
49 changing external environment to think instead of adaptation as a reconfiguration of infrastructures and
50 institutions to build resilience in the surrounding environment (Pelling, 2010; Matyas and Pelling, 2015).
51 Reflective and iterative learning is integral to fostering transformative capacity (c.f. Luederitz et al., 2017).
52 Transformative capacity extends across multiple agency levels or geographical locations, as well as various
53 domains (Wilson et al., 2013; Olsson, Bodin and Folke, 2010; Keeler et al., 2019b). The components of
54 transformative capacity in cities and settlements can be grouped into three categories (see Table 6.9): (1)
55 agency and forms of interaction, (2) development processes, and (3) relational dimensions (Wolfram, 2016).
56 Alongside different forms of technical expertise, there is a need to broaden the interventions of
57 disadvantaged populations in urban sustainability (Wolfram, Borgström and Farrelly, 2019).

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 1

 2 Table 6.9 presents a defined framework of ideas that local institutions- mostly local governments- can put
 3 into practice to improve their adaptive capacity. Enabling transformative capacity requires novel governance
 4 arrangements based on broad participation, a diversity of actor-networks, socially embedded leadership, and
 5 empowerment of communities, alongside an understanding of the system dynamics, which refers to system
 6 awareness, collective visions, practical experimentation, reflexivity, capacity building, and institutional
 7 mainstreaming, and the multiple levels of agency or scales (Ziervogel, Cowen and Ziniades, 2016; Ziervogel,
 8 2019a; Wolfram, 2019; Hölscher and Frantzeskaki, 2020; Castán Broto et al., 2018). Many of the
 9 transformative capacity components are already visible in local adaptation actions, but many efforts
10 emphasize one element at others' expense, without delivering a systemic perspective. In particular, measures
11 to facilitate the empowerment of communities, reflexivity, and social learning are rare but often point
12 towards heightened capacities for transformative, alongside incremental, adaptation (Castán Broto et al.,
13 2018). Transformative capacity frameworks may foster inclusive governance to deliver risk management that
14 works for the poor in countries such as South Africa (Ziervogel, 2019a).

15

16

17 Table 6.9 Components of urban transformative capacity with broader relevance for multiple forms of adaptation
18 (Wolfram, 2016).

    Component                                                Manifests in...

    Agency and Inclusive, multiform urban                    Citizens and/or civil society organizations participating directly
    interaction governance (C1)                              in planning and/or decision-making processes.

                       Participation / inclusiveness (C1.1)

                 Diverse governance modes /                  Different and various stakeholders working together and
                 Networks (C1.2)                             building connections between sectors in different manners.

                 Sustained intermediaries and                An intermediary positioned between the stakeholders of a
                 hybridization (C1.3)                        project.
                 Transformative leadership (C2)              Leadership acting as a collaborative driving force in an
                                                             initiative.
                 Empowered communities (C3)                  Either analysing or addressing social needs.
                 Social needs (C3.1)
                 Autonomous communities (C3.2)               Integrating into the design of the project different aspects of
                                                             community empowerment.

    Development System awareness (C4)                        Agendas aiming to tackle sustainability challenges after
    processes Baseline analysis and system(s)                deliberate analysis of urban systems.

                       awareness (C4.1)                      Explicitly tackling systemic barriers to change.

                       Recognition of path dependencies
                       (C4.2)

                 Foresight (C5)                              Involvement of various and multiple stakeholders in knowledge

                 Co-production of knowledge (C5.1) production processes.

                 A collective vision for change (C5.2) An explicit future vision shared among stakeholders as a means
                                                               for motivating partners and fostering commitments.

                 Alternative scenarios, future               Comparative scenarios that evaluate the mutual shaping of
                 pathways (C5.3)                             social, ecological, economic and technological dimensions.

                 Experimentation with disruptive             The deliberate use of experiments or ideas that seek to challenge
                 solutions (C6)                              the existing landscape of established policies, technologies or
                                                             social practices.

                 Innovation embedding (C7)                   Project stakeholders sharing resources for capacity development

                 Resources for capacity development outside the project to disseminate and multiply results.

                 (C7.1)

                 Mainstreaming transformative action Attempts to generalise the project operation or results beyond

                 (C7.2)                                      the initial context of an application.

                 Regulatory frameworks (C7.3)                A new regulation was established as a result of the project or as
                                                             part of the project activities.

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    Relational Reflexivity and social learning (C8) Stakeholders reflecting on learning and capacity building

    dimensions                                processes.

                 Working across human agency  Project activities contributing to capacity development across
                 levels (C9)                  human agency levels.

                 Working across levels and scales Project activities contributing to building capacity across

                 (C10)                        geographical or political-administrative levels.

1

2

3 6.4.5 Financing Adaptation in Cities, Settlements and Infrastructures

 4

 5 The amount invested in urban adaptation is limited. The Cities Climate Finance Leadership Alliance tracked
 6 USD 3.7 billion of investments in adaptation projects in 2017-2018, of which only 3-5% had an urban
 7 component (Richmond et al., 2021). Cities and settlements frequently face barriers of inadequate financing
 8 for climate adaptation and mitigation (Cook and Chu, 2018).Finance barriers interact with economic barriers
 9 and socio-economic conflicts and need to be considered within an integrated perspective (Hinkel et al.,
10 2018).

11

12 Many early leaders in climate adaptation are, therefore, perhaps unsurprisingly, political capitals or financial
13 centers in the global North with much larger resource envelopes and well-developed fiscal and financing
14 capacities (Westerhoff, Keskitalo and Juhola, 2011; Shi, Chu and Debats, 2015).

15

16 The funding required to deliver climate change adaptation will depend on choices made about climate
17 mitigation (Masson-Delmotte and Waterfield, 2018). Still, the cost of adapting to a global temperature
18 increase of 1.5°C will be a fraction of the cost of adapting to a global temperature increase exceeding 3oC
19 (Pörtner et al., 2019; Shukla et al., 2019; Hoegh-Guldberg et al., 2018). It will also depend on selected
20 adaptation options, as they have different capital requirements, operating costs, and returns on investment
21 (See 6.3). Finally, costs depend on financing sources and mechanisms selected.

22

23 Broadly, there are two options for adaptation investment: funding ­ direct expenditure in preparation for or
24 response to climate change impacts ­ and financing ­ the deployment of market-based instruments to attract
25 third-party resources to an adaptation action (Keenan, 2018; Banhalmi-Zakar et al., 2016). Using funding can
26 be a lower-cost strategy, as there is no third party expecting a return on investment. However, using
27 financing can expand the total resources available for adaptation (White and Wahba, 2019).

28

29 The choice of funding and financing mechanism is often based on implicit economic world views (Keenan,
30 Chu and Peterson, 2019) or on the technical support available to subnational governments, such as preparing
31 municipal bonds or contracting for public-private partnerships (Bisaro and Hinkel, 2018). The urban finance
32 literature has long called for critical interrogation of these choices, as adaptation finance has profound justice
33 implications (Khan et al., 2020). However, the literature on adaptation investments is limited (Harman,
34 Taylor and Lane, 2015; Keenan, Chu and Peterson, 2019). The use of municipal debt such as green bonds,
35 for example, intensify the financial and environmental risks borne primarily by the poor, the working class,
36 or people discriminate against because of race, sexual orientation, or ability (Bigger and Millington, 2019).

37

38 The climate imperative has not yet fundamentally changed urban infrastructure investment (White and
39 Wahba, 2019). Mobilizing adaptation investment in urban areas continues to depend on strengthening public
40 finance capacities (particularly evaluating and integrating climate risk into economic decisions) and meeting
41 private investors and lenders' expectations. Climate change creates new investment risks and physical risks
42 (Martimort and Straub, 2016), and highlights the limitations of current models to account for risk and
43 uncertainty when pricing investments (Keenan, 2018). Private investors and lenders do not seem ready to
44 provide adaptation finance on significantly easier or cheaper terms than conventional finance (White and
45 Wahba, 2019). However, a variety of means for financing climate change adaptation in urban areas exist
46 (Table 6.10).

47

48

49 Table 6.10 Finance instruments to deliver adaptation in urban areas (source: adapted from (Richmond et al., 2021) and
50 (UN-Habitat, 2016b)).

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   Type of      Finance source           Instruments              Examples of specific instruments in urban settings
   finance

   Public       Municipal                Local revenue            Utility fees
                government               generation               Open space funds/land value capture
   Public                                                         General obligation bonds
   finance      State/Provincial         Grants, incentives,      Local property, income, and sales taxes
                government               technical assistance     Insurance
                National government      funds                    Tax advantages
                                                                  Low-cost project debt
                National DFIs            Grants, project debt     Infrastructure investment funds
                Bilateral DFIs           (low-cost market         Shared taxes
                Multilateral DFIs        rate), technical         Intergovernmental funding transfers/revenue sharing
                                         assistance, risk         Risk mitigation support of PPP
                                         instruments              Project level debt
                                                                  Project preparation facilities and other technical
                                                                  advisory
                                                                  Insurance

                Climate funds            Grants, debt,            Dedicated climate fund

                                         equity, guarantees

   Private      Commercial FIs           Project debt and         Internal climate risk mitigation
                                         equity (market-          PPP Financing
                                         rate), guarantees        Climate loans

                PE/Infrastructure        Project equity           Direct urban infrastructure investments
                funds                    (market rate)            Corporate equity investment
                Institutional investors  Project debt and         Direct urban infrastructure investment
                                         equity (market-          Corporate debt and equity investments
                                         rate)

                Private insurance        Insurance                Public and private risk mitigation
                                                                  Catastrophe bonds
                                                                  Parametric insurance

                Corporate actors         Balance sheet            Internal risk mitigation
                Household                financing and            Leasing
                                         project equity           PPP
                                         (market rate)
                                         Balance sheet            Internal climate risk mitigation
                                         financing

                Non-profits,             Grants, technical        Microfinance
                philanthropies and       assistance,              Impact investment
                foundations              donations

                Communities              Grants and               Risk sharing
                                         collective support       Upgrading funds
                                                                  Community development funds
                                                                  Crowdfunding

1

2

3 6.4.5.1 Urban adaptation financing gap

4

5 Cities and settlements in higher-income countries typically have access to funding that could be used to
6 enhance resilience and build adaptive capacity; this includes both the private resources of individual
7 households and firms (which varies significantly within and among cities) and public budgets of different
8 government tiers (see Table 6.10).

9

10 Depending on fiscal devolution levels within a country, public revenues may be collected and managed
11 primarily at the national, state, metropolitan, or local level. In federal countries, subnational governments

12 collect an average of 49.4% of public revenues compared to only 20.7% in unitary countries (OECD/UCLG,

13 2019). For example, subnational revenues represent over a quarter of total public revenues in Belgium,

14 Canada, and Denmark, but less than 5% in Greece, Ireland, and New Zealand (OECD/UCLG, 2019). The
15 share of the national revenue transferred to subnational governments also varies significantly among
16 countries: grants and subsidies account for over three-quarters of subnational government revenue in Malta,

17 but less than a quarter of subnational revenue in Iceland (OECD/UCLG, 2019). A local government's

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 1 capacity to collect revenues is further mediated by incomes within a city (which dictates the prospective tax
 2 base) and the capacity of civil servants to administer taxes, fees, and charges. The result is that metropolitan
 3 and local governments' budgets vary dramatically, across and within countries. For example, per capita
 4 municipal budgets vary from $1,114 in Saskatoon and $2,682 in Peterborough (Canada), $2,635 in Leipzig
 5 and $3,638 in Freiburg (Germany), to $4,907 in Bristol and $5,612 in Aberdeen (the United Kingdom)
 6 (Löffler, 2016).

 7

 8 Revenue streams are often insufficient relative to the scale of adaptation requirements. For example, Kano,
 9 Nigeria, is a large urban area that urgently needs investment in human development and climate resilience,
10 but where a fragmented local government has little capacity to finance their climate plans (Mohammed,
11 Hassan and Badamasi, 2019). Many local governments are unable to mobilise funds for adaptation as they
12 face competing priorities, meaning that resources for resilience must be allocated by higher levels of
13 government (Hughes, 2015) ­ which also perceive opportunity costs to adaptation investments. Funding
14 from non-state actors is, therefore, proving important. For example, in the U.S., private foundations and non-
15 profit organizations account for 17% and 16% of adaptation support in urban areas (Carmin, Nadkarni and
16 Rhie, 2012). However, tapping into these funding sources raises complex questions about accountability and
17 ownership of urban adaptation (Chu, 2018a). Land reclamation may foster real estate markets and mobilize
18 finance for adaptation, as shown in Germany, the Netherlands, and the Maldives (Bisaro et al., 2019).

19

20 City governments need to anticipate climate shocks and stresses and design their operating models and
21 investment plans accordingly to ensure financial resilience (Clarvis et al, 2015). Climate risks threaten fiscal
22 models, for example, a drought may disrupt water revenues by reducing total water consumption and
23 incentivizing households and firms to invest in independent water storage or supply infrastructure (Simpson
24 et al., 2019). Storm surges and sea-level rise may threaten sunk investments in revenue-generating
25 infrastructures, such as toll roads or electricity generation and transmission systems. .

26

27 6.4.5.2 Barriers to adaptation investments

28

29 Common sources of adaptation finance might include donor agencies including the Green Climate Fund;
30 sovereign funds (e.g. the Bangladesh Climate Change Resilience Fund) and private finance from commercial
31 banks, investment companies, pension funds and insurance companies (Floater et al., 2017). These capital
32 sources have different risk-return expectations and investment horizons, so they will suit different types and
33 stages of projects. Many subnational governments in the global North have access to well-developed
34 domestic, if not global, capital markets to raise and steer finance for urban investment (Banhalmi-Zakar et
35 al., 2016).

36

37 However, investments in ex-ante urban climate adaptation may prove less attractive to these financiers than
38 other opportunities because of their long maturities and high risk (Keenan, Chu and Peterson, 2019) (see also
39 Table 6.11). Many generate economic returns primarily through avoided losses from climate impacts, which
40 are difficult to measure and are, in any case, more attractive to funders than financiers (Kaufman, 2014). Ex
41 post, insurance already plays a critical role in protecting urban households, firms, and other stakeholders
42 from the full economic costs of high-severity, low-frequency events by sharing risk over time and space.
43 Insurance can also be designed to incentivize risk-reducing behaviours and investments (Banhalmi-Zakar et
44 al., 2016; Paddam and Wong, 2017). Some researchers suggest that, in urban environments, insurance
45 practices are helping to establish adaptation and risk as a new area of public health and public protection. For
46 example, local governments are using new risk transfer instruments, such as reinsurance and catastrophe
47 bonds, to fund investments in resilience projects and disaster recovery (Collier and Cox, 2021). However,
48 private-sector insurance's commercial feasibility depends on more robust estimates of current and future
49 risks, and premiums commensurate with the ability and willingness of consumers to pay. Therefore, ex-ante
50 investments must complement insurance schemes to improve climate modeling and reduce climate risk
51 (Surminski, Bouwer and Linnerooth-Bayer, 2016). The private sector also faces practical barriers to invest in
52 adaptation.

53

54

55 Table 6.11 Barriers to finance adaptation in urban areas (Richmond et al., 2021)
         Barrier Application to urban adaptation
         Barriers to adaptation finance

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    Poor policy Environment                  Municipal policy environment lacks conditions supportive to private
                                             adaptation investment (e.g., lack of requirements that private sector
    Poor institutional environment           organizations operating in cities implement climate risk mitigation
                                             strategies or invest in systemic resilience).
    Poor market environment                  Legal and regulatory infrastructure in the city lacks clarity of purpose
                                             towards addressing urban climate risks (e.g., no limitations on
    High cost of projects and unknown value  development in high climate risk areas).
    add                                      Market environment is unsupportive towards adaptation investment
    Lack of technical capacity               (e.g., lack of creditworthy partner municipalities for private sector
                                             engagement).
    Limitations of private                   The value or benefit of the technology is uncertain; private sector actors
    insurance                                do not sufficiently consider climate risk in decisions; upfront costs of
                                             technology are high.
                                             Prospective users of technology do not have technical capacity to
                                             implement (e.g., limited or siloed expertise in implementing resilient
                                             urban infrastructure solutions).
                                             Insurance has to date largely not been engaged in cities to efficiently
                                             transfer risk or incentivize adaptive action and the private insurance
                                             industry is facing considerable risk associated with the accelerating
                                             impacts of climate change in

1

2

3 National governments typically determine the fiscal transfers that subnational governments receive and the
4 taxes, fees, and charges they permit to collect (see for example (CBO, 2016)). Local governments may
5 strengthen their own-source revenue collection and management capacities to exploit these funding streams
6 better and improve their balance sheets, but their total budget will be limited to these funding sources
7 (Ahmad et al., 2019). The amount of local public funding available for urban adaptation depends on the
8 relationships across different government levels.

 9

10 Similarly, mobilizing private finance for urban adaptation projects demands robust institutional, fiscal, and
11 regulatory frameworks, which are typically national authorities' responsibility. For local governments to
12 access private finance for adaptation may require national (or in federal countries, state) governments to
13 reform policies and rules governing municipal borrowing, public-private partnerships, land value capture
14 instruments, and other financing mechanisms (Ware and Banhalmi-Zakar, 2017). Such fiscal reforms tap into
15 fundamental political and policy issues, such as local governments' autonomy or the tariff-setting powers of
16 national ministries (Gorelick, 2018; White and Wahba, 2019).

17

18 Access to private finance can support infrastructure development through private provisioning, public-
19 private Partnerships (PPP), and public debt arrangements (high confidence) (see also 6.4.1.2). Private
20 provisioning attracts coastal adaptation investment when returns are high (e.g., when there is a real estate
21 market associated with it) (Bisaro and Hinkel, 2018). Public-private partnerships attract investments from
22 dredging and construction companies that involve a large share of operational costs (Bisaro and Hinkel,
23 2018). Public debt instruments appear less successful in supporting investment in adaptation infrastructure.
24 Real estate firms focus on adaptation actions if they perceive climate change impacts such as flooding may
25 impact their activity, mostly focusing on adaptation action as a means to gain competitive advantage
26 (Teicher, 2018).

27

28 There have been numerous attempts to innovate in climate finance, for example, mobilising community and
29 cooperative forms of finance, or crowdfunding which have already proven effective in the context of
30 mitigation (De Broeck, 2018). A well-studied instrument in urban environments is land-value capture. Land-
31 value capture refers to communities' ability to capture the benefit of increased land values that result from
32 public investment or other government actions (Germán and Bernstein, 2020). There is considerable
33 potential to mobilize land-value capture for adaptation (limited evidence, medium agreement), but its
34 potential remains unexplored (Dunning and Lord, 2020). While there are numerous examples of the
35 mobilization of land-value capture to finance sustainable development action (Li and Love, 2019; Wang,
36 Samsura and van der Krabben, 2019), there is limited evidence of its use in climate adaptation (see case
37 study 6.2). These innovations are particularly important in contexts were resources are very constrained,
38 such as in the financing of adaptation in African cities (See box 6.7).

39

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 1 Corruption in urban adaptation and disaster risk management finance is a considerable but little researched
 2 challenge observed from all world regions (Sanderson et al., 2021). Corruption generates maladaptation
 3 increasing risk, for example where infrastructure is constructed with faulty design, substandard materials and
 4 inadequate maintenance (Kabir et al., 2021). More widely, corruption increases vulnerability and reduces
 5 capacity by damaging the body politic, distorting markets and reducing economic growth (Alexander, 2017).
 6 The construction and infrastructure industries are repeatedly identified as sources of corruption (GIACC,
 7 2020; Chan and Owusu, 2017; Sanderson et al., 2021). Corruption and misuse of climate finance is
 8 exacerbated by limited public access to information, political considerations in finance decision-making and
 9 lack of accountability for decisions and actions (Kabir et al., 2021). In construction Owusu et al (2019) found
10 causes included too-close relationships, poor professional ethical standards, negative industrial and working
11 conditions, negative role models and inadequate sanctions throughout the phases of construction. Post-
12 disaster response and reconstruction, and periods of surge funding following international or national policy
13 priorities are especially vulnerable to corruption with increased funding and pressure to lower norms of
14 financial management (Imperiale and Vanclay, 2021). Mixed delivery mechanisms have been shown to
15 reduce corruption, for example where civil society organizations are involved in project approval stages.
16 Though there is also a risk that civil society organisations will themselves become entangled in corruption.
17 International donors have a role to play in working with government and civil society to promote wider
18 scrutiny and transparency of financing processes and project delivery through promoting media and press
19 freedom and legislation for access to information to reduce corruption by enhancing transparency and
20 accountability (Kabir et al., 2021).

21

22 Expanding the resource envelope available for adaptation investment is often beyond the authority or
23 competency of city governments. Sovereign and state governments have critical roles to play in providing
24 funding or securing finance for adaptation investments. Such role is particularly important where the impacts
25 of climate change are distributed inequitably across a country so that the costs borne by a city may exceed
26 local budgets.

27

28

29 [START BOX 6.7 HERE]

30

31 Box 6.8: Challenges to Investment in Adaptation in African Cities

32

33 In Africa, new investment in institutions and other enabling conditions for climate-resilient urban
34 development (Robins, 2018) While several studies reveal the net economic benefit of climate-resilient, low-
35 carbon African cities (Global Commission on Economy and Climate, 2017), structural impediments remain
36 to the mobilization of investment for the types of public good infrastructure that would unlock this benefit
37 (Dodman et al., 2017).

38

39 Since the 1960s, Gross Capital Formation (sometimes called Gross Domestic Investment) has been less than
40 22% in Africa, whilst in East Asian countries, it has risen to 42% (OECD, 2016). Africa faces an estimated
41 40% infrastructure financing gap, but this gap is almost certainly higher in the continent's rapidly growing
42 cities (Baker & McKenzie, 2015). Relative poverty, weak or absent local fiscal systems, and contested tenure
43 that prevents land being used as collateral, have restricted investment in African cities (Berrisford, Cirolia
44 and Palmer, 2018; Dodman et al., 2017). Sub-Saharan African countries are reaching the 40%-urban
45 threshold at national per capita incomes of around $1,000 per annum, significantly poorer than South-East
46 Asian and Latin American cities at the same level of urbanization (Freire, Lall and Leipziger, 2014).
47 Absolute poverty, in conjunction with weak revenue collection and low levels of investment, render
48 conventional infrastructure finance difficult (Smolka, 2013; Global Commission on Economy and Climate,
49 2017; Berrisford, Cirolia and Palmer, 2018; Cirolia and Mizes, 2019). Sprawled urban development in Africa
50 might make the provision of public services, both more energy-intensive and three times more expensive
51 than high-density developments (Collier and Venables, 2016).

52

53 Data on private finance in African cities are inadequate (OECD, 2017), but all of Africa secured just 3.5%
54 ($46 billion) of global FDI, despite a 10.9% increase in 2018 (UNCTAD, 2019). Mining and the extraction
55 and processing of fossil fuels accounted for almost a third of greenfield FDI in Africa in 2018 (UNCTAD,
56 2019). The FDI secured by cities has tended to serve an urban elite and has been used to build shopping
57 malls, housing settlements, and airlines (Watson, 2015). It is also unevenly distributed across the continent

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1 and within cities. Five countries, Egypt, South Africa, Congo, Morocco, and Ethiopia accounted for more
2 than half the total FDI in 2018 (UNCTAD, 2019), leaving large parts of Africa's growing cities described by
3 financiers as "high risk" and their citizens deemed "unbankable" (UCLG, 2016).

4

5 Private financiers have begun entering public-private partnerships with African cities, often supported by
6 bilateral agreements between the respective countries, including the growing number of Asian and Middle-
7 Eastern countries contributing to infrastructure in African cities (Cirolia and Rode, 2019). In the absence of

8 enforceable spatial plans and strong urban governance, the risk remains that individual investment projects

 9 that are completed will aggregate to create urban systems that are at risk from climate change through the
10 locking-in of inequality, urban sprawl, flooding and greenhouse gas emissions (Dodman et al., 2017;
11 Wachsmuth, Cohen and Angelo, 2016). These risks will constitute a future burden for asset owners,
12 financiers, and insurers and cause a progressive hemorrhaging of economic opportunities in Africa's urban
13 centres (UCLG, 2016).

14

15 Securing climate finance for urban development is contingent upon robust multi-level governance
16 arrangements (Tait and Euston-Brown, 2017; OECD/UN-Habitat, 2018). Such investments are needed for
17 cities that do not yet have the balance sheets or rate-paying citizens required to enter financial markets on

18 favourable terms. Similarly, Central Banks have a crucial role in managing the transition risks within cities
19 and limiting the systemic impact of stranded urban assets due to technology shifts or sea-level rise
20 (Safarzyska and van den Bergh, 2017).

21

22 New energy, water, and sanitation technologies alter the public good nature of urban services and offer novel
23 opportunities for private sector financiers and blended finance. Still, financial sector innovation remains
24 necessary if technological innovation is to be scaled (Cities Climate Finance Leadership Alliance, 2015;

25 European Environment Agency, 2020). UNEP has cited anecdotal evidence of a "quiet revolution" towards a

26 more developmental and sustainable global finance sector, in part due to global Environmental, Social, and
27 Governance requirements, and industry initiatives within the financial and insurance sectors (UNEP, 2015).
28 Scope remains to strengthen Development Finance Institutions programmes such as the World Bank's City
29 Creditworthiness Programme and the activities of China's ExIm Bank with a bespoke urban climate
30 dimension.

31

32 [END BOX 6.7 HERE]

33

34

35 6.4.6 Monitoring and Evaluation Frameworks for Adaptation used in Cities, Settlements and

36  Infrastructures

37

38 Urban adaptation plans can focus attention on the needs of marginalised or vulnerable communities

39 including the elderly, children and the disabled (Dahiya and Das, 2020; Yang, Lee and Juhola, 2021).
40 However, monitoring and evaluation (M&E) frameworks for adaptation are far from being fully developed

41 and operationalized both in theory and in practice for cities, settlements, and infrastructures. See also Section

42 17.5 for an assessment of monitoring and evaluation in climate adaptation. Despite significant experience on

43 the application in other sectors (e.g., health, water, industry, or business) or with other climate change
44 objectives (e.g., emissions reduction), the assessment of adaptation efforts has been to date under-theorized
45 in current urban adaptation literature (Berrang-Ford et al., 2019; Leiter et al., 2019; Olazabal et al., 2019b).

46 There is also limited evaluation of new social innovations of the last two decades, including participatory
47 budgeting, social financing, crowdfunding, and low-cost urban infrastructure that can be enabling conditions
48 for transformative urban adaptation (Dahiya and Das, 2020; Caprotti et al., 2017).

49

50 The challenges related to the evaluation of adaptation progress (lack of methods, agreed metrics, data, and

51 definitions, including the ambiguity of the concept of "adaptation") have been widely recognised after the
52 Paris agreement by multiple organisations, including the OECD, the World Bank, the European Environment
53 Agency, the Global Environment Facility (Ford et al., 2015; Magnan, 2016; Bours, McGinn and Pringle,
54 2014). Monitoring and evaluation systems in urban areas will necessarily be incremental and additive, and

55 will have to build on existing indicator systems (Solecki and Rosenzweig, 2020). There is a need to develop

56 practical and efficient frameworks to assess adaptation progress across all levels of public and private
57 decision-making. This should include the assessment and consideration of top-down adaptations alongside

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 1 informal, bottom-up, community actions, or corporate-led programs developed to reduce vulnerabilities and
 2 climatic risks and increase resilience (high confidence, high agreement).

 3

 4 On the one hand, there is a need to guarantee that planned adaptation actions are efficient, just and equitable
 5 (Olazabal et al., 2019b), including being able to disaggregate for example by gendered impacts. On the other
 6 hand, there is a need to observe if and how environmental, social and economic vulnerability and climatic
 7 risk conditions evolve with time. Surveillance, monitoring and evaluation facilitate adaptation decision-
 8 making by linking three aspects (Berrang-Ford et al., 2019): (1) changing vulnerabilities and risks, (2)
 9 established adaptation goals and targets, and (3) adaptation efforts put in place. The process will help
10 evaluate whether current adaptation efforts are sufficient or adequate, thus, enabling the learning process that
11 adaptation action requires (Haasnoot, van't Klooster and Van Alphen, 2018; Klostermann et al., 2018).

12

13 Monitoring and evaluation of Government led urban adaptation in major cities around the globe is largely
14 missing (Araos et al., 2016; Olazabal et al., 2019a). This reveals: (1) a lack of awareness by local adaptation
15 managers about the critical importance of monitoring and evaluation systems in adaptation decision-making,
16 (2) inadequacy, irrelevancy, or underuse of available monitoring and evaluation resources, or (3) a lack of
17 knowledge, capacity, and resources to make monitoring and evaluation work in practice at city scale.

18

19 Olazabal et al (2019b) argue that six components are at least required to make monitoring and evaluation
20 operational for urban adaptation planning: (1) the definition of a context-specific tailored system adapted to
21 existing local institutions, (2) the definition of a responsible party (public authority, department, group or
22 organization) that will be in charge of monitoring and evaluation system management, (3) the definition and
23 assignation of the appropriate budget over time, (4) the identification of monitoring objectives and
24 indicators, (5) the definition of a method and process to evaluate outcomes of the monitoring process and
25 eventually, (6) the reporting process (how and who the outputs will be reported to). Klostermann et al.
26 (2018) emphasize the importance of learning through iterative cycles of selection of monitoring objectives,
27 procedures, data collection and evaluation, and inputs to adaptation policy and planning processes (see also
28 discussion of evaluation and learning in section 17.5.1.7). Yet, practical exemplary approaches are still
29 missing.

30

31 The IPCC's Fifth Assessment Report acknowledged the lack of standard metrics to measure and monitor
32 success in urban adaptation and suggested a list of indicators that could be developed, while also taking note
33 of the localized nature of adaptation (see also (Rufat et al., 2015)). However, predominant approaches are
34 typically not conducted at the appropriate scale to inform adaptation decision making (Ford et al., 2018).
35 While some scholars advocate the use of a unifying indicator of social vulnerability (Spielman et al., 2020),
36 other scholars propose to develop flexible sets of comparable indicators that can be adjusted to different
37 contexts (Leiter et al., 2019). Risk-based approaches are seen as an alternative in a context where the
38 monitoring of decision-relevant variables in urban climate adaptation planning is essential to link climatic
39 risk assessment and action (Hallegatte and Engle, 2019; Kingsborough, Borgomeo and Hall, 2016;
40 McDermott and Surminski, 2018). Because of the need to define normative frameworks for risk evaluation -
41 what is acceptable, for what purpose and for how long (Galarraga et al., 2018) - these approaches may offer
42 an opportunity for the generation of a shared understanding on goals and limitations of adaptation
43 (McDermott and Surminski, 2018). However, risk-based indicators may also create a bias towards
44 quantifiable variables that tend to be based on climatic modelling outputs, engineering, or financial
45 assessments. Based on this and various examples of urban development projects, Hallegatte and Engle
46 (2019) claim it is important to consider output-based indicators and process-based indicators that talk about
47 government, voice, and empowerment. Overall, dozens of indicator-based approaches to assess climate
48 adaptation have been proposed across the scientific and policy literature, especially in the broader framework
49 of (community) resilience assessment tools (Sharifi, 2016; Feldmeyer et al., 2019), and in different sectors,
50 e.g., the climate benefits of nature-based solutions (Kabisch et al., 2016; Donatti et al., 2020). Although these
51 efforts may help to mainstream the evaluation of adaptation in current city evaluation initiatives, the
52 development of comprehensive monitoring and evaluation systems is lacking.

53

54 There is little evidence on how best to make monitoring and evaluation approaches practical at the local
55 scale. Cities worldwide face important social, environmental, and economic conflicts related to resource
56 inequality, poverty, environmental pollution, and social tensions that coexist with climatic risks. It makes
57 sense to integrate climate change adaptation assessment goals and needs into existing frameworks for the

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 1 sake of efficiency. This will benefit small urban areas and cities in developing regions that often face data
 2 scarcity and may also find available indicators irrelevant to their realities and, thus, be required to adjust
 3 them (Simon et al., 2016). Efforts to coordinate frameworks for the assessment of sustainability (e.g., Local
 4 Agenda, sustainability appraisals), resilience (e.g., 100 Resilient Cities, new standards for urban resilience),
 5 GHG emissions reporting (e.g., Global Covenant of Mayors for Energy & Climate) can be deployed to learn
 6 about contexts. However, they need to be applied with caution as enforcing external requirements may lead
 7 to local tensions during their application (see for example (Roberts et al., 2020)). In a context where
 8 adaptation efforts need to be aggregated and evaluated across nations (Magnan, 2016) and their implications
 9 on wider objectives such as sustainable development and social justice need to be assessed (Long and Rice,
10 2019), urban adaptation monitoring and evaluation can inform national and international processes that
11 enable a global stocktake of adaptation.

12

13 6.4.7 Enabling Transformations

14

15 Growing awareness of the interlocking of drivers of urban change and vulnerability has motivated an interest
16 in transformational approaches to adaptation action in cities, settlements, and infrastructure. While the idea
17 of transformation has been adopted across the field, there is no consensus about what an urban
18 transformation that addresses adaptation means. There is no one single transformative solution or approach
19 relevant in every case (Chu, Schenk and Patterson, 2018; Shi, 2019; Goh, 2019). What constitutes `urgent'
20 and `far-reaching' transformation depends on the local community's expectations and ideas (Choko et al.,
21 2019).

22

23 Transformation is often approached as a process of institutional transformation, akin to the process described
24 in section 6.4.2 (see, for example (Duijn and van Buuren, 2017)). Transformation engages with critiques of
25 adaptation or risk reduction as an individual responsibility (Sou, 2018). The idea is to use transformation to
26 focus on coordinating collective efforts (Haque et al, 2014). The coordination of multiple actors is a
27 condition to enable transformative institutions (Torabi et al, 2018) and link adaptation action to development
28 efforts (Chu et al, 2017; Roberts and O'Donoghue, 2013). The role of communities and citizens in such an
29 approach to transformation is ambiguous. Sometimes communities and citizens are presented as critical
30 agents of transformation (Limthongsakul et al, 2017). Other times, however, they are simply situated within
31 strong and durable networks that provide the institutional setting to build resilience (Daničre et al., 2016).
32 Despite the political nature of transformative approaches and the evidence that transformative approaches
33 rely on protest and political activism, few authors recognise this strategy (but see (Bahadur and Tanner,
34 2014; Chu, Anguelovski and Roberts, 2017; Dierwechter and Wessells, 2013)).

35

36 Transformation is also more than a single instance of institutional change. Historical perspectives on
37 transformation enable an understanding of the chain of institutional changes that ultimately lead to
38 significant or far reaching reconfiguration of infrastructure and service provision (Rojas et al, 2015)..
39 Paradigm changes, such as new engagements with nature and green infrastructure, will improve adaptation
40 outcomes (Roberts et al., 2012). Changes of paradigms, however, are not inherently positive and may clash
41 with existing interests or involve trade-offs with other priorities. When care is taken to ensure greater
42 inclusion in urban decision making, disadvantaged, vulnerable communities are less likely to be
43 disadvantaged. For example, indigenous traditions of nature management provide entry points for the
44 sustainable management of resources, such as seed banks, urban agriculture, and the local management of
45 watersheds and floods, may be at odds with conventional structures of expert knowledge (Cid-Aguayo, 2016;
46 Chandra and Gaganis, 2016). These traditions are vital both because of the solution space that they open in
47 the local context and how they serve to create resilience through collective and intergenerational learning
48 (Chandra and Gaganis, 2016).

49

50 While aspects of transformative capacity identified in the literature may facilitate far-reaching change, there
51 is limited evidence of actual transformations as an outcome of adaptation. While community-led resilience
52 agendas may tackle poverty-related issues, they struggle to tackle city-wide structural forms of inequality
53 (Chu, 2018b). Processes of shared learning and co-production of knowledge can reinforce existing power
54 dynamics and be limited by technical framings of vulnerability that marginalize political issues (Orleans
55 Reed et al., 2013). These issues are especially acute in relation to land-use decisions where short-term fiscal
56 and commercial interests conflict with long-term vulnerability reduction objectives (Brown, Dayal and
57 Rumbaitis Del Rio, 2012). It can be difficult for adaptation actions to target cities' underlying political-

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 1 economic structure, such as entrenched political-economic interests, elite influence over decision-making, or
 2 neoliberal planning logics that maintain and reproduce inequality (Chu, Anguelovski and Roberts, 2017).
 3 Urban resilience plans may be formulated in disconnection from broader development strategies, which leads
 4 to a limited ability to tackle underlying structures of political power and urban development practices
 5 (Weinstein et al, 2019). Evidence from Kolkata demonstrates the limitations of resilience plans to address
 6 underlying conditions of vulnerability, including the commodification of hazardous land, under-provision of
 7 informal settlements, and spatial segregation of the urban poor (Rumbach, 2017).

 8

 9 Planning for transformative adaptation is more likely where communities can learn collectively (medium
10 evidence, medium agreement) (Restemeyer, van den Brink and Woltjer, 2017; Kabisch et al., 2017; Fraser et
11 al., 2017; Putri, Dalimunthe and Prasojo). Greater citizen engagement facilitates implementing specific
12 measures for radical policymaking or the mainstreaming of environmental knowledge into adaptation
13 practices (Reed et al, 2015). DIY planning, in which stakeholders focus on creating and improving specific
14 urban spaces they inhabit, has led to urban greening experiments led by civil society that change paradigms
15 of urban and environmental management (Cloutier, Papin and Bizier, 2018). Social learning may occur
16 through combinations of activism and collaboration with and between informal settlement dwellers, as
17 shown in adaptation experiences in informal settlements in Hanoi and Bangkok (Daničre et al., 2016).. The
18 adaptation process can benefit from the inclusion of multiple sources of knowledge for social learning,
19 including universities but also communities and citizens (Chu, 2018b). Citizens assemblies are increasingly
20 recognized as spaces for transformative adaptation (Muradova, Walker and Colli, 2020), although their
21 potential influence at different government levels is still not fully understood.

22

23 The integration of multiple forms of knowledge leads to social learning (medium evidence, high agreement).
24 Indigenous knowledge and local knowledge can provide essential insights into community needs and
25 experiences of housing and urban infrastructure to inform climate adaptation, including improper waste
26 disposal, inadequate drainage, and poor sanitation, but there is significant variation in community knowledge
27 networks (Roy et al., 2018b; Douglas et al, 2018; Waters and Adger, 2017). It is important to identify and
28 address barriers to the incorporation of Indigenous knowledge and local knowledge, such as the dominance
29 of scientific knowledge, oppression and/or racism and fragmentation of knowledge including gender and
30 generational divides (see Burke and Heynen, 2014; Whyte, 2017; Victor, 2015; Lövbrand et al., 2015; Kelly,
31 2019).The incorporation of Indigenous knowledge in urban decision making requires a constructive dialogue
32 with scientists and urban planners.

33

34 Indigenous knowledge and local knowledge have an important role to play in urban planning and
35 management. They can support impact detection and evaluation in urban areas (Codjoe et al, 2014), weather
36 forecasting in urban areas (Magee et al., 2016; Ebhuoma and Simatele, 2019), climate change adaptation in
37 urban agriculture (Wahab and Popoola, 2018; Solomon et al., 2016), urban food security (Simatele and
38 Simatele, 2015), planning and managing urban solid waste (Kosoe et al, 2019), urban flood management
39 (Thorn et al, 2015; Jameson and Baud, 2016; Hooli, 2016), drought perception and coping strategies
40 (Saboohi et al., 2019), and ecological restoration and urban commons management (Nagendra, 2016;
41 Nagendra and Mundoli, 2019). They can help define baselines for past climate and ecological change
42 providing an historical perspective on changes in urban commons such as lakes and trees (Nagendra, 2016)
43 as well as past climatic changes or climate baselines (Ajayi and Mafongoya, 2017) and Shifting Baseline
44 Syndrome (Fernández-Llamazares et al., 2015; Soga and Gaston, 2018) (see Businger et al., 2018 for a
45 review of Hurricane history in Hawaiian newspapers; also Wickman, 2018). Incorporating Indigenous
46 knowledge and local knowledge can help generate more people-oriented and place-specific approaches
47 leading to adaptation policies that foster identity, dignity, self-determination, and better collective decision-
48 making and capacity to act (Preston, 2017; McShane, 2017) (see also 6.1).

49

50 Envisioning development alternatives through adaptation as a first step towards transformative adaptation
51 can leverage social learning. Experiences of migration, length of residence, and the density of local social-
52 networks impact social learning opportunities and underscore why context-specific social education is vital
53 (Waters and Adger, 2017; Karunarathne and Lee, 2020). Learning across and between communities can be
54 enhanced when care is taken to understand local challenges. Given power relationships, cultural needs, and
55 community aspirations, a top-down approach to information sharing is generally less effective than
56 community partnerships and co-created knowledge at surfacing visions and strategies for getting past baked-
57 in, unequal and unsustainable development assumptions and practices (medium evidence, high agreement)

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1 (Clemens et al., 2016; Thi Hong Phuong, Biesbroek and Wals, 2017; Fitzgerald and Lenhart, 2016; Fisher
2 and Dodman, 2019). Social learning in formal and informal urban contexts is also enhanced when care is
3 taken to ensure multiple stakeholders have opportunities to understand a variety of viewpoints, values,

4 resources, and ideals, and that these view-points are clearly identified in decision making (Thi Hong Phuong,

5 Biesbroek and Wals, 2017). However much social learning still happens only after a crisis, for example in
6 urban water adaptation and new knowledge is often frustrated by the lock in of powerful local institutions
7 and groups (Johannessen et al., 2019). Social learning is, however, only one component of the development

8 of climate-resilient pathways. System perspectives theorize the possibility of tipping points, leverage points,

 9 or disruptive technologies to challenge the stable regime to create a broader reconfiguration (Chapter 17;
10 O'Neill et al., 2018).

11

12

13 Case Studies

14

15 Case Study 6.1: Urbanization and Climate Change in the Himalayas ­ Increased Water Insecurity for the

16  Poor

17

18

19 Figure 6.6 Urbanisation in Hindu-Kush Himalayan Region Figure based on (Singh et al., 2019b)

20

21

22 The Hindu Kush Himalayan region extends roughly over 3,500 km covering eight countries - Afghanistan,
23 Pakistan, Nepal, China, India, Bhutan, Bangladesh, and Myanmar. Projections show that by 2050, more than
24 50% of the population in Hindu Kush countries will live in cities (UNDESA, 2014). The region is home to
25 10 major river basins that feed south and south-east Asia. In 2017, the total population in the ten major river
26 basins with their headwaters in the region was around 1.9 billion, including 240 million in the mountain and
27 hills of the Hindu Kush (Wester et al., 2019). The region is characterized by unique mountain topography,
28 climate, hydrology, and hydrogeology. Each one of these factors plays an important role in determining the
29 availability of water for people living in the Himalayas (Nepal, Flügel and Shrestha, 2014; Scott et al., 2019;
30 Prakash and Molden, 2020). The total landmass that can support physical infrastructure for towns to develop
31 is much less in the Hindu Kush Himalayan region as compared to the plains. Due to this physical constraint,
32 the process of urbanization is slow in the region. Only 3 per cent of the total population in the region live in
33 larger cities and 8 per cent in smaller towns (Singh et al., 2019b). However, there has been an increase in

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 1 urbanization largely due to regional imbalances in providing economic opportunities for the poor. People
 2 from rural areas are flocking to the nearest urban centres in search of employment and other economic
 3 opportunities (Singh and Pandey, 2019). As a result, the share of urban population is increasing in the region,
 4 while that of the rural population is declining.

 5

 6 One of the major challenges of urbanization in the Himalayas is sprawling small towns with populations of
 7 under 100,000 (see Figure 6.6). These towns are expected to become major urban centres with a decade due
 8 to high growth rate. A recent study by Maharjan et al. (2018) on migration documented that 39% of rural
 9 communities have at least one migrant, of whom 80% are internal and the remaining 20% are international.
10 Around 10 per cent of the migration is reported as environmental displacement. Most of the migration is of
11 male which forms an important aspect of gendered vulnerability (Sugden et al., 2014; Goodrich, Prakash and
12 Udas, 2019). The ever-expanding urban population in the Himalayas generates many challenges especially in
13 the context of climate change adaptation. First, unplanned urbanization is causing significant changes in land
14 use and land cover with recharge areas of springs being reduced. Most of the towns in Hindu Kush
15 Himalayan region meet their water needs using supplies from springs, ponds, and lakes which largely
16 interlinked systems, Water insecurity in hill towns are becoming an order of the day (Virk et al., 2019; Bharti
17 et al., 2019; Singh et al., 2019a; Sharma et al., 2019). Second, climate-induced changes in the physical
18 environment include increased rainfall variability. Due to this, heavy rains are becoming frequent and are
19 leading to more landslides. Third, global warming has increased the average temperature in the Himalayas
20 which has caused glacier melt and subsequent change in hydrological regimes of the region. One of the
21 contributing factors of glacial decline is also the deposition of black carbon (Gautam et al., 2020; Gul et al.,
22 2021) which is contributed by burning of crop residue in Punjab (Kant et al., 2020). These critical stressors ­
23 climatic and non-climatic, are adversely affecting the socio-ecology of urban conglomerations in the region
24 (Pervin et al., 2019). Encroachment or degradation of natural water bodies and the disappearance of
25 traditional water systems such as springs are evident (Shah and Badiger, 2018; Sharma et al., 2019). While
26 water availability in these towns has been adversely affected by the climatic and socio-economic changes,
27 demand for water has increased greatly (Molden, Khanal and Pradhan, 2018). Some of the towns are major
28 tourist attractions that create a floating population in peak tourist seasons challenging the carrying capacities
29 of the towns. The residents must cope with water scarcity as the demand for water increases in peak seasons
30 and water distribution through the public water supply systems becomes highly inequitable (Raina, Gurung
31 and Suwal, 2018). The usual challenges of utilities being inefficient applies in these areas too though it
32 becomes much more critical as the sources of water are limited and the local geology limits the ability to
33 access groundwater. All these processes are resulting in increased water insecurity for the poor and
34 marginalised in urban towns of Hindu Kush (Prakash and Molden, 2020). To cope with the scarcity situation,
35 people are adapting through various means such as rationing of intra-household water access, groundwater
36 extraction to access water supply (Virk et al., 2019; Bharti et al., 2019; Sharma et al., 2019). This is due to
37 lack of long-term strategies and options provided by utilities.

38

39 Case Study 6.2: Semarang, Indonesia

40

41 The City of Semarang, on the northern coast of Central Java in Indonesia, has a population of nearly 1.8
42 million (CBS, 2019). The city has experienced rapid urbanization over last three decades, with the
43 population almost doubling and density reaching 4,650 people per square kilometre (Handayani and
44 Rudiarto, 2014; Handayani et al., 2020b). Semarang is vulnerable to sea level rise, tidal flooding, and
45 inundation (Suhelmi and Triwibowo, 2018; Yuniartanti, Handayani and Waskitaningsih, 2016), risks which
46 are worsened by land subsidence along the coast (Abidin et al., 2013). Globally, land subsidence is a notable
47 compounder of climate change-induced sea level rise and coastal flooding (Bagheri et al., 2021). In
48 Semarang, the land subsidence rate is projected to be up to 60 millimetres per year (Abidin et al., 2013; Bott
49 et al., 2021). Approximately 20% of the city's coastline is characterized as extremely vulnerable due to sea
50 level rise and enhanced land subsidence (Husnayen et al., 2018), with the north-eastern portions of the city
51 experiencing larger subsidence than the rest (Yastika, Shimizu and Abidin, 2019). Associated public health
52 and sanitation risks are also evident, including increasing outbreaks of dengue fever and diarrhoea (Pratama
53 et al., 2017; Indonesia Ministry of Health, 2020).

54

55 The City of Semarang first engaged with climate change in 2009, when the Rockefeller Foundation launched
56 the Asian Cities Climate Change Resilience Network (ACCCRN), an initiative to develop resilience capacity
57 across secondary and rapidly growing cities in South and Southeast Asia (Reed et al., 2015). Semarang was a

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 1 pilot city for ACCCRN from 2009 to 2016, when it introduced a participatory approach to planning and
 2 decision-making that challenged the government-dominated tradition in the city, and in turn played a key
 3 role in Semarang's climate adaptation and resilience planning process (Orleans Reed et al., 2013; Moench,
 4 2014; Kernaghan and Da Silva, 2014). A City Team was formed in 2010 consisting of City Environmental
 5 Agency (BLH ­ Badan Lingkungan Hidup), Regional Disaster Management Agency (BPBD - Badan
 6 Penanggulangan Bencana Daerah), Water Resources Management Office (PSDA - Kantor Dinas
 7 Pengelolaan Sumber Daya Air), Regional Planning and Development Agency (BAPPEDA - Badan
 8 Perencanaan Pembangunan Daerah), local universities, and NGOs such as the Bintari Foundation, with
 9 technical support from Mercy Corps Indonesia (Nugraha and Lassa, 2018).

10

11 The City Team was first established within the City Environment Agency (BLH) but was then transferred to
12 the Development and Planning Agency (BAPPEDA) (Lassa, 2019). This corresponded to a shift in framing
13 of climate change from an environmental priority to encompassing broader development issues such as
14 economic development, housing, and infrastructure delivery. By asserting that climate change affects the
15 operations of every critical sector across the city, the number of municipal agencies involved in climate
16 change programming increased significantly (Setiadi, 2015). Most notably, this approach helped the
17 municipal health agency to recognize the relationship between climate change and health (Setiadi, 2015),and
18 helped to shift the emphasis of dengue fever management towards a more proactive community-based health
19 early warning system (Pratama et al., 2017). In 2017, these measures helped to reduced dengue fever
20 infection rates by 56% compared to 2011-2016 levels (Indonesia Ministry of Health, 2020). ACCCRN also
21 supported policy experimentation through implementing rainwater harvesting facilities and a community-
22 based flood early warning system (Archer and Dodman, 2015; Yuniartanti, Handayani and Waskitaningsih,
23 2016; Sari and Prayoga, 2018). These projects were designed in conjunction with national government
24 investments in flood management infrastructure, which led to a reduction in the city's inundated area by 24%
25 or approximately 1% of the total urban area (Semarang City Government, 2016).

26

27 Building on Semarang's ACCCRN experience, the city then became a member of the Rockefeller
28 Foundation's 100 Resilient Cities (100RC) program between 2016 and 2018. As in ACCCRN, this new
29 process emphasized stakeholder involvement, with the previous City Team recast as a team of City
30 Resilience Officers (CRO), which was in turn led by the City Mayor and received strategic advisory support
31 from the City Secretary. Semarang synthesized its experiences in climate adaptation planning through the
32 Resilient Semarang Strategy published in May 2016 (Semarang City Government, 2016). The Resilient
33 Semarang Strategy (2016) acknowledged that urban resilience must be pursued in a comprehensive and
34 inclusive manner and highlighted 18 strategies across 6 themes ­water and new energy, new economy,
35 disaster and disease, integrated mobility, transparency of public information, and competitive human
36 resource ­ to be mainstreamed into the revision of the Mid-Term Regional Development Plan (RPJMD -
37 Rencana Pembangunan Jangka Menengah Daerah) of 2016-2021. City Resilience Officers were formally
38 appointed to serve on the RPJMD team, thereby formalizing climate resilience as a critical item on the
39 RPJMD program list.

40

41 100RC engagement allowed Semarang's resilience programs to appear on 100RC's "marketplace" of
42 municipal projects, allowing them to be connected with bi-/multi-lateral donor resources, while continuing to
43 align projects with goals articulated within the Mid-Term Regional Development Plan. The 100RC
44 marketplace is a resilience platform that showcases particular initiatives of 100RC network cities to potential
45 resilience partners, thereby attracting investment and donor support to Semarang's resilience programs.
46 Examples include the Water as Leverage (WaL) project that has been working to conserve urban water
47 resources in the face of climate change since 2018 (Handayani et al., 2020a; Laeni et al., 2021) and the
48 Transboundary Flood Risk Management Through Governance and Innovative Information Technology
49 Program (TRANSFORM) that has been helping Semarang tackle flood risks beyond city boundaries through
50 reforestation, development of dry wells and swales in upstream areas, as well as promoting cross-region
51 dialogue (Global Resilience Partnership, 2018). Other collaborations focused on developing resilience
52 indicators (ARUP, 2018; Rangwala et al., 2018). For example, the Zurich Flood Resilience Program
53 implemented resilience measurement tools in 16 sub-districts along the West Flood Canal. Results of the
54 assessment were then used to develop local disaster contingency plans.

55

56 The conclusion of the Rockefeller Foundation's formal engagement in Semarang in 2018 has brought forth
57 questions about continued financial and institutional support for climate adaptation action in the city.

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 1 Increasing land subsidence will also likely overwhelm current efforts to incrementally adapt to sea level rise
 2 and coastal flooding (Abidin et al., 2013). Still, the Semarang case study does highlight several key lessons
 3 for urban climate governance in secondary rapidly urbanizing cities in the Global South. First, transnational
 4 institutions and partnerships are critical enablers (Aisya, 2019; Setiadi, 2015; Chu, Hughes and Mason, 2018;
 5 Handayani et al., 2020a). Institutions such as the Rockefeller Foundation foster programmes and investment
 6 in the city, leverage access to adaptation funding, accelerate climate mainstreaming into wider urban sectors,
 7 and promote better knowledge management (Setiadi, 2016). However, such opportunities are also supported
 8 by the city's ability to further mobilize its own resources in the long-term and remove its dependency on the
 9 national government and transnational supporters (Handayani et al., 2020a). Second, scaling up of
10 programmes and replication of adaptation actions are increasingly important to close the gap between
11 planning and implementation (Setiadi, 2016). It is evident that increased community empowerment and
12 participation can help fill this gap (Hadi, 2018; Miladan, 2016) but this must also be evidence-based to
13 ensure its applicability and effectiveness (Suarma et al., 2018). Questions remain around how to determine
14 and assess evidence-based participatory adaptation at the local level. Third, sustainable financing (from both
15 external and internal sources) to support proposed adaptation strategies is essential as it allows for more
16 capacity building, technology transfer, and program implementation in the long run (Handayani et al., 2020a;
17 Laeni et al., 2021; Hadi, 2017). An example is the development of a water retention on the eastern coast of
18 Semarang using a collaborative financing model, which helped further adaptation by protecting water
19 resources for local industries as well as promote the idea of land value capture for community residents.

20

21 Case study 6.3: Institutional Innovation to Improve Urban Resilience: Xi'xian New Area in China

22

23 Located in Northwest China and the Silk Road Economic Belt, Xi'Xian covers a total of 882 square
24 kilometres of the border zone of two cities of Xi'an and Xianyang, Shaanxi province. Xi"xian accommodates
25 a registered population of 1.06 million with a planned area of 272 square kilometers reserved for urban
26 development. As a new engine for promoting the West Development Strategy and people-centred
27 urbanization in the northwest China, Xi'xian has paved the way for China's ecological city agenda since
28 January 2014.

29

30 Xi'xian aims to build a 'modern garden city' when it was selected as national demonstration sites for Sponge
31 City (SC) during 2015-2018 and Climate Resilient City (CRC) during 2017-2020. Under the changing
32 climate, the old cities of Xi'xian suffers urban heat island, drying and water scarcity, heavy rains and
33 waterlogging, thunderstorm and so on, which bring adverse effects to transportation, construction, cultural
34 relics tourism resources, and other industries (Ma, Yan and Zeyu, 2021). Sponge City status requires
35 innovation to reduce flood risk through design to absorb, store, and purify rainfall and storm water in an
36 ecologically friendly way that reduces dangerous and polluted runoff. When required, the stored water is
37 released and added to the urban water supply (MoHURD, 2014). As Climate Resilient City the aim is to
38 adapt to climate risk and environmental change, by integrating climate resilience into urban renewal and
39 revitalization.

40

41 In practice, building ecological cities in China has focused more on hard measures than institutional
42 innovation (Li et al., 2020). Among one of nineteen national-level New Areas in China, Xi'xian enjoys
43 special preferential policies in the fields of fiscal autonomy, investment and tax policy and permission in
44 land utility for industrial development purpose. These policy freedoms allow Xi'Xian to explore adaptation
45 options. This has opened engagement with business through an urban construction investment group
46 sponsored and invested in jointly by Xi'Xian Management Committee (administrative authority) and local
47 enterprises (Wei and Zhao, 2018). Second, the municipal government has simplified administrative systems
48 to reduce the project waiting period from evaluation to approval to 50 days. Third, a green financial
49 mechanism creates a leverage effect for national funding, including the first provincial Green Sponge
50 Development Fund (1.2 billion RMB) and in Shaanxi, special funding from the Urbanization Development
51 Fund (2.64 billion RMB). Furthermore, a public-private partnership model with a whole-lifecycle-
52 management approach has been introduced, raising funding of 1.24 billion RMB with a packaged project
53 including public pipelines and sewage water treatment facilities.

54

55 Such institutional and financial support have allowed Xi'xian to implement a Pilot Construction Plan and
56 Three-year Action Plan for Adapting to Climate Change. In 2020, Xixian formed an urban ecology system
57 including 21 square meters of green space per capita. The old cities' underground drainage pipe network has

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 1 been replaced by sponge designs such as green corridors, grass ditches, water storage gardens, and recessed
 2 green spaces. The 10 waterlogging prone points in Xi'xian New Area have been eliminated and the green
 3 area has alleviated urban heat, with average temperature about 1 degree lower than the neighboring densely
 4 populated mega-cities of Xi'an and Xianyang. Groundwater in the New Area has also risen by 3.43 meters
 5 compared with 2015.

 6

 7 At the end of 2020, Xi'xian New Area has built 2.4 million square meters of modern garden cities, more than
 8 50 kilometers of sponge roads, 1.4 million square meters of resilient park green space and established a
 9 green coverage of more than 50% of the urban space. The target of becoming a green city in which everyone
10 can "see green in 100 meters, step into garden every 300 meter" has been realized (Ma et al., 2021). The
11 urban parks and green spaces play a role in regulating local microclimate and also improve the urban
12 environmental amenities for residents. In a comprehensive performance assessment for the Climate Resilient
13 Cities facilitated by the Climate Change Department of the Ministry of Ecology and Environment (MEE),
14 the Xi'xian ranked the No.9 among all of the twenty eight pilot cities.

15

16 Case Study 6.4: San Juan: Multi-Hazard Risk and Resilience in Puerto Rico and its Urban Areas

17

18 This case study illustrates multi-hazard risk and reviews the formation of a multi-stakeholder adaptation
19 governance regime as one response to this.

20

21 In two weeks in 2017 Puerto Rico experienced two powerful hurricanes, Irma (category 5) and María
22 (category 4). The compound effects decimated the island's power, water, communications, and
23 transportation infrastructure and an estimated 2,975 people lost their lives (Irvin-Barnwell et al., 2020;
24 Santos-Burgoa et al., 2018). Soon after, while many homes still had no electricity or roofs and the tree
25 canopy was still bare, Puerto Ricans were faced with cascading effects including environmental health
26 impacts from air pollution, extreme heat and mosquitoes (Ortiz et al., 2020). In 2020, while still recovering
27 Puerto Ricans experienced earthquakes, extreme African dust events, intense coastal and urban floods, and
28 the COVID-19 pandemic (Keck, 2020; NASA Explore Earth, 2020; NASA/JPL-Caltech, 2020). These
29 events continue to unveil unresolved conditions of social vulnerability and its root causes in economic
30 poverty, social inequities, aged and deteriorating infrastructure, and population loss (Bonilla and LeBrón,
31 2019). Combined with limited past investment in climate change adaptation and underlying governance
32 challenges including corruption, bankruptcy, and political crisis (Holladay et al., 2019) this has constrained a
33 more climate resilient development for Puerto Rico.

34

35 It is in this context that government, academic institutions and local civil society have taken important steps
36 and often joint action towards mitigation and adaptation. Federal funding included US$20 billion of disaster
37 recovery funding with US$8 billion allocated for adaptation and resilience projects, such as flood risk
38 mitigation. During the year 2020, the Federal Emergency Management Agency (FEMA) approved US$13
39 billion to rebuild the power grid and education system (Delgado, 2020). These programs allow communities
40 and local governments to plan and implement strategies and build new infrastructure that reduces risks and
41 builds long-term adaptive capacities. The Government of Puerto Rico also approved two key climate
42 adaptation policies in 2019. The Puerto Rico Mitigation, Adaptation and Resilience to Climate Change Law
43 (Law 33, Senate Bill PS 773) established, for the first time in the island's history, a legal framework that
44 acknowledges that the climate is changing and threatens the quality of life. The law recognizes important
45 scientific projections for the island, including an increase of 0.5 to 1 meter in sea levels by 2015 and
46 maximum temperatures of up 2.5 C and precipitation decrease of up to 50% by 2100 (Gould et al., 2018).
47 The law generated the formation of an Expert and Advisory Committee on Climate Change to develop the
48 plan with specific recommendations and present it to the Legislature within a year of the passing of the law
49 in 2020. Along with strategies to specifically protect and build the resilience of urban and rural communities
50 to future climate disasters, the law establishes sustainable development goals, including water and food
51 security, urban planning and densification, and transition to renewable and alternative forms of energy. The
52 energy target is reinforced by another key state policy approved in 2019 in response to the failed energy
53 infrastructure during Hurricane María, the Puerto Rico Energy Public Policy Act (Senate Bill PS 1121). This
54 law calls for a transition to 100% renewable and alternative energy by 2050.

55

56 Puerto Rico has a strong science base that produced extensive knowledge on climate change and
57 sustainability long before Hurricane María. The Puerto Rico Climate Change Council has collected and

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 1 synthesized scientific information for Puerto Rico since before its formation in 2009. Many Puerto Rican
 2 scientists were also editors and authors on Chapter 20: US Caribbean Region for 4th US National Climate
 3 Assessment (Gould et al., 2018). The National Institute of Island Energy and Sustainability (INESI in
 4 Spanish) recently published a catalog with more than 60 scientists and experts working on energy and
 5 sustainability innovations in the University of Puerto Rico (UPR) system. The scientific community became
 6 very active after the hurricane in efforts to empower local groups and communities to build more sustainable
 7 and resilient futures. UPR Environmental Health scientists worked with communities to design and
 8 implement risk reduction action plans, including nature-based solutions, through the Community Climate
 9 Actions Plans and the Puerto Rico Community Resiliency Initiative sponsored by Fundación Comunitaria de
10 Puerto Rico and Education Development Center-Regional Education Laboratories, Northeast and Islands. A
11 successful example of these alliances is the development of the First Solar Power Community in Toro Negro,
12 Puerto Rico. These initiatives were inspired by principles of human-centered design, a problem-solving
13 approach that starts with the people impacted the most by the problem to be solved. In San Juan, the capital
14 and major urban centre of the island, scientists from UPR and the US Forest Service International Institute of
15 Tropical Forestry worked with local stakeholders and communities to develop sustainable and transformative
16 urban futures with the support of the Urban Resilience to Extreme Events Sustainability Research Network
17 (UREx SRN). The UREx SRN is a knowledge network of ten cities in the US and Latin America and twenty
18 other institutions building scientific knowledge, models, and participatory tools to build resilience and
19 transformative capacities for cities.

20

21 Perhaps the greatest source of adaptive capacity that emerged after the hurricane came from the civic sector
22 and community-based organizations and local residents. Hundreds of non-profit and grassroots organizations
23 became active in disaster recovery and are now catalyzing actions to advance social transformation and
24 sustainable development. In the energy sector, numerous communities and NGOs developed new action
25 plans to promote transitions to renewable energy and community-based micro grids, such as the Queremos
26 Sol initiative (https://www.queremossolpr.com/), and the establishment of solar panels in community centers
27 and residences by the Puerto Rico Community Foundation and Resilient Power Puerto Rico. The San Juan
28 Bay Estuary Program, an NGO in the San Juan metropolitan area, launched alongside the Clinton Global
29 Initiative the development of a Watershed-Based Mitigation Plan, the first watershed-based plan for the
30 metro region. The organization has established resilience hubs to support the community with critical
31 resources, communications, and energy supply during an emergency. In many of the most isolated areas
32 across the island where government aid did not reach them for months, the communities that self-organized
33 during recovery are also leading examples of community social-ecological resilience. In Utuado, one of the
34 hardest hit areas by the hurricane, their main community organization known as COSSAO (Corporación de
35 Servicios de Salud y Desarrollo Socioeconómico, El Otoao) emerged from the hurricane with a strong and
36 holistic sustainable development vision - the Tetuan Reborn initiative - to improve the socio-economic status
37 and health of community members while building capacity for disaster resilience through various initiatives.
38 The long-term outcome of this initiative is to support efforts toward self-empowerment within
39 neighbourhoods by identifying and designing viable solutions to hurricane- related and economic
40 development challenges specific to the local context including constructing a primary health care clinic, a
41 public health promoter programme, pursuing farms rehabilitation, promoting agritourism, agro-therapy and
42 education (Holladay et al., 2019).

43

44 Adaptation efforts, however, continue to face many governance hurdles. Up to 2020, only 2-3% of the
45 US$20 million Federal Government recovery funds had been spent with hundreds of families that lost their
46 homes or roofs in 2017 yet to receive the help they need (Colón Almenas, 2020). Lack of administrative
47 capacities, coordination across sectors and efforts, transparency and accountability are some of the
48 governance barriers that keep recovery and transformation efforts from materializing (Lamba Nieves and
49 Marxuach, 2020). Puerto Ricans are now contending with the reality that the disaster they are experiencing is
50 not an outcome of a singular event but of multiple hazards converging with pre-existing vulnerabilities and
51 low adaptive capacities creating severe multi-hazard risk to the island (Eakin, Muńoz-Erickson and Lemos,
52 2018; Gould et al., 2018). Many Puerto Ricans now question when the disaster began and when it ended
53 because they have been living in a state of chronic crisis (Bonilla and LeBrón, 2019).

54

55 Case Study 6.5: Climate-resilient Pathways in Informal Settlements in Cities in Sub-Saharan Africa

56

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 1 Informal settlements account for over three-quarters of residential areas in sub-Saharan Africa and have
 2 grown rapidly over the last three decades (Visagie and Turok, 2020). Informal settlements will remain home
 3 to a significant proportion of the urban population of this region which is projected to grow by 2.5 times
 4 between 2020 and 2050 (UNDESA, 2018), driven by a complex set of underlying factors including socio-
 5 economic conditions, inadequate planning systems, local and foreign investment patterns, and rural to urban
 6 migration (De Longueville et al., 2020). Yet residents of informal settlements are often excluded from
 7 macro-level visions and policies that seek to make cities safer and improve resilience (Adenle et al., 2017;
 8 Pelling et al., 2018b). This case study compares the experience of collective action to manage risk in the
 9 informal settlements of Freetown, Sierra Leone with other cases in Sub-Saharan Africa. These examples
10 show how local knowledge and capacity, engagement of policy makers in meaningful ways with residents of
11 informal communities, and institutional change, can combine to deliver adaptation outcomes at a city scale
12 (Kareem et al., 2020).

13

14 Despite their diversity and differences across the continent (Kovacic et al., 2019), informal settlements are
15 frequently located in hazard-prone areas, with residents living in precarious housing conditions on marginal
16 lands (Badmos et al., 2020; Kironde, 2016), lacking essential services and risk reducing infrastructure, and
17 often developing outside the legal systems intended to record land tenure and ownership (Satterthwaite et al.,
18 2020; Adelekan et al., 2015). Consequently, they are particularly vulnerable to climate change, and the urban
19 poor residents suffer disproportionate burdens and losses from natural hazards, which undermines urban
20 resilience (Williams et al., 2019). Recent impacts from flooding have brought wide-spread devastation to
21 urban poor residents in major coastal urban centres including Accra, Lagos, Freetown, Maputo, and Dar es
22 Salaam, resulting in injury and death, displacement of people, loss of assets, destruction of public
23 infrastructure, and disruption to livelihoods and economies (Douglas et al., 2008; Adelekan, 2010; Yankson
24 et al., 2017; Allen et al., 2017). Flooding and long-term inundation also lead the spread of diseases and
25 health risks (Sverdlik, 2011; Zerbo, Delgado and González, 2020). Climate change will also bring stresses
26 such as city-wide reductions in freshwater availability, and heat waves that have particularly severe
27 consequences for residents of poorly built homes in informal settlements (Pasquini et al., 2020; Kayaga et
28 al., 2021; Wilby et al., 2021).

29

30 In response to these risks, a wide range of adaptation efforts have been implemented in cities across sub-
31 Saharan Africa (Hunter et al., 2020). In Freetown, informal settlement residents have led data generation
32 efforts that capture the value of local knowledge in understanding climate risk. Through partnerships with
33 NGOs and research institutions, informal settlement residents have mapped climate hazard hotspots using
34 geo-referenced tools, producing both digital and hardcopy outputs that serve as a blueprint for climate-
35 informed community development discourses (Allen et al., 2020b; Visman et al., 2020). Similarly, residents
36 of informal settlements in Dar es Salaam, Tanzania, have profiled community climate and health risks by
37 using an adaptation of the 'Action at the Frontline' methodology developed by the Global Network of Civil
38 Society Organisations for Disaster Reduction (GNDR). Locally-informed risk profiles support the
39 development of community action plans based on prioritization and ranking of scaled-down interventions
40 that communities can collectively do on their own (Osuteye et al., 2020). This process highlights the lived
41 experiences of climate change, and allows communities to develop deliberation spaces, communal solidarity
42 and cohesion, and share adaptation strategies (Sakijege et al., 2014). Such sharing and peer-to-peer learning
43 is particularly useful because adaptive capacities are unevenly distributed among exposed populations
44 (Ajibade and McBean, 2014). The community-generated assessments and data consider the range of
45 environmental, socio-economic, and political factors that contribute to a better understanding of how climate
46 change affects the vulnerability of low-income urban residents, and how this changes over time.

47

48 Data that is generated and owned by residents of informal settlements provides a basis for making the risks
49 facing these neighbourhoods more visible to city planners, and for enabling collaboration between a range of
50 urban stakeholders (Dobson, 2017). In Freetown, this process has been led by the Federation of the Urban
51 and Rural Poor (FEDURP) and the Centre for Dialogue on Human Settlement and Poverty Alleviation
52 (CODOHSAPA). The FEDURP belongs to the global Slum Dwellers International network, committed to
53 empowering poor residents in urban spaces and has a presence in several other African cities (Macarthy et
54 al., 2017). With the support of CODOHSAPA, FEDURP coordinates Community Development Committees
55 (CDC) and Community Disaster Management Committees (CDMC) in nearly all the informal settlements in
56 the city. Both CODOHSAPA and FEDURP work closely with the local research institution, the Sierra Leone
57 Urban Research Centre (SLURC). SLURC has played an essential role in curating spaces for continuous

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 1 learning and relationship-building between FEDURP and community residents, including the formation of
 2 "Community Learning Platforms" (CLP) for mixed groups of community actors (City Learning Platform,
 3 2019) to build their capacities to address climate risk collectively. This is done by drawing on the data,
 4 agency and mobilisation potential of community organizations in informal settlements. In the coastal
 5 settlement of Cockle Bay at the western end of the city, uncontrolled traditional land reclamation ("banking")
 6 along the shores progressively exposed residents to perennial floods from tidal surges, and the settlement
 7 received regular threats of evictions from city authorities. However, residents have drawn on their climate
 8 risk knowledge and hazard profiling to self-manage a process of action planning resulting in a decision to
 9 prohibit further land reclamation. It also identified and demarcated an exterior boundary of the settlement
10 and planned and constructed new drainage channels to carry away run-off water within the community
11 (Allen et al., 2017). The community organizations have subsequently successfully negotiated with the
12 Ministry of Environment to formalise this new exterior boundary, which has led to the authorities dropping
13 their threats of evictions.

14

15 The approach taken in Freetown demonstrates a pathway to adaptation that is based on a more people-
16 centred approach to urban planning that understands the aspirations of urban residents, addresses climate
17 risk, and advances sustainable development (Woodcraft et al., 2020; Fraser et al., 2017). It further provides
18 an example of the ways in which different sources and scales of data can be co-produced (Kovacic et al.,
19 2019) and targeted interventions can be co-designed with community residents (Musango et al., 2020). The
20 community-generated data on climate and health risks and the subsequent strategic action plans developed
21 through local community organizations' work have been recognized and incorporated into a new city-wide
22 initiative led by the Office of the Mayor, dubbed Transform Freetown (Allen et al., 2020a). The action has
23 expanded the political space for the urban poor's collectives to strategically engage in urban resilience
24 planning, highlighting the value and potential of participatory processes and community-generated data.

25

26

27 [START CROSS-WORKING GROUP BOX URBAN HERE]

28

29 Cross-Working-Group Box URBAN: Cities and Climate Change

30

31 Authors: Xuemei Bai (Australia), Vanesa Castan Broto (United Kingdom/Spain), Winston Chow
32 (Singapore), Felix Creutzig (Germany), David Dodman (Jamaica/United Kingdom), Rafiq Hamdi (Belgium),
33 Bronwyn Hayward (New Zealand), iir Kilki (Turkey), Shuaib Lwasa (Uganda), Timon McPhearson
34 (USA), Minal Pathak (India), Mark Pelling (United Kingdom), Diana Reckien (Germany), Karen Seto
35 (USA), Ayyoob Sharifi (Japan/Iran), Diána Ürge-Vorsatz (Hungary)

36

37 Introduction

38

39 This Cross-Working Group Box on Cities and Climate Change responds to the critical role of urbanisation as
40 a megatrend impacting climate adaptation and mitigation. Issues associated with cities and urbanization are
41 covered in substantial depth within all three Working Groups (including WGI Box TS.14, WGII Chapter 6
42 `Cities, settlements and key infrastructure'; WGII regional chapters; WGII Cross-Chapter Paper `Cities and
43 settlements by the sea'; WGIII Chapter 8 `Urban systems and other settlements'). This Box highlights key
44 findings from Working Groups II and III and substantial gaps in literature where more research is urgently
45 needed relating to policy action in cities. It describes methods of addressing mitigation and adaptation in an
46 integrated way across sectors and cities to advance sustainable development and equity outcomes; and
47 assesses the governance and finance solutions required to support climate resilient responses.

48

49 Urbanisation: A Megatrend Driving Global Climate Risk and Potential For Low-Carbon and Resilient
50 Futures

51

52 Severe weather events, exacerbated by anthropogenic emissions are already having devastating impacts on
53 people who live in urban areas, on the infrastructure that supports these communities and those of many
54 other distant places (high confidence) (Cai et al., 2019; Folke et al., 2021). Between 2000 and 2015, the
55 global population in locations that were affected by floods grew by 58-86 million (Tellman et al., 2021). The
56 direct economic costs of all extreme events reached 210-268 billion USD in 2020 (Aon, 2021) or about $0.7
57 billion per day ­ this figure does not include knock-on costs in supply chains or days off work lost so that the

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 1 actual economic costs could be far higher. Depending on RCP, between half (RCP2.6) and three-quarters
 2 (RCP8.5) of the global population could be exposed to periods of life-threatening climatic conditions arising
 3 from coupled impacts of extreme heat and humidity by 2100 (see WGII 6.2.2.1; WGII Figure 6.3; (Mora et
 4 al., 2017a; Zhao et al., 2021; Huang et al., 2019)).

 5

 6 The interdependencies between infrastructure, services and networks driven by urban production and
 7 consumption mean that urban systems are now global ­ remittance flows and investments reach into rural
 8 places shaping natural resource use far from the city and bring risk to the city when these places are
 9 impacted by climate change. This urbanization megatrend (Kourtit, Nijkamp and Scholten, 2015) amplifies
10 as well as shapes the potential impacts of climate events. It provides the economic and institutional
11 framework for integrating the aims and approaches that can deliver mitigation, adaptation and sustainable
12 development (medium evidence, high agreement) (Zscheischler et al., 2018; Dawson et al., 2018;
13 Tsavdaroglou et al., 2018). For cities facing flood damage wide-ranging impacts have been recorded on other
14 urban areas (Simpson et al., 2021; Carter et al., 2021) as production and trade is disrupted (Shughrue et al.,
15 2020). In the absence of integrated mitigation and adaptation across and between infrastructure systems and
16 local places, impacts that bring urban economies to a standstill can extend into supply chains or across
17 energy networks causing power outages.

18

19 Urban settlements are drivers of climate change, generating about 70 percent of global CO2eq emissions
20 (high confidence) (WGI Box TS.14; WGIII 8 ES; WGII 6.1, WGII 6.2). This global impact feeds back to
21 cities through the exposure of infrastructure, people and business to the impacts of climate related hazards. In
22 especially the larger cities this climate feedback is exacerbated by local choices in urban design, land-use,
23 building design, and human behaviour (Viguié et al., 2020) that shape local environmental conditions. Local
24 and global conditions influence the nature of hazards in urban centres: urban form can add up to two degrees
25 to warming, concretisation of open space can increase run-off, and building height and orientation influences
26 wind direction and strength (WGII 6.3).

27

28 Building today for resilience and lower emissions is far easier than retrofitting tomorrow. As urbanisation
29 unfolds its legacy continues to be the locking in of emissions and vulnerabilities (high confidence) (Ürge-
30 Vorsatz et al., 2018; Seto et al., 2016). Retrofitting, disaster reconstruction and urban regeneration
31 programmes offer scope for strategic direction changes to low-carbon and high resilience urban form and
32 function if they are inclusive in design and implementation. Rapid urban growth means new investment, new
33 buildings and infrastructure, new demands for energy and transport and new questions about what a healthy
34 and fulfilling urban life can be. The US$90 trillion expected to be invested in new urban development by
35 2030 (NCE, 2018), is a global opportunity to place adaptation and mitigation directly into urban
36 infrastructure and planning, social policy including education and health care and environmental
37 management (Ürge-Vorsatz et al., 2018). If this opportunity is missed, if business as usual urbanisation
38 persists, then social and physical vulnerability will be not be so easily confronted.

39

40 The benefits of actions taken to reduce GHG emissions and climate stressors diminish with delayed action,
41 indicating the necessity for rapid responses. Delaying the same actions for increasing the resilience of
42 infrastructure from 2020 to 2030 is estimated to have a median cost of at least US$1 trillion (Hallegatte et
43 al., 2019) while also missing the carbon emissions reductions required in the narrowing window of
44 opportunity to limit global warming to 1.5°C (WGI). In contrast, taking integrated actions towards
45 mitigation, adaptation and sustainable development will provide multiple benefits for the health and
46 wellbeing of urban inhabitants and avoid stranded assets (WGII 6.3, WGII 17; WGIII 5; WGIII 8.2; Cross-
47 Chapter Box FEASIB in Chapter 18).

48

49 The Policy-Action Gap: Urban Low-Carbon and Climate Resilient Development

50

51 Cities are critical places to realize actions on both adaptation and mitigation simultaneously with potential
52 co-benefits that extend far beyond cities (medium evidence high agreement) (Grafakos et al., 2020; Göpfert,
53 Wamsler and Lang, 2019). Given rapid changes in the built environment, transforming the use of materials
54 and the land intensiveness of urban development including in many parts of the Global South in the next
55 decades will be critical, as well as mainstreaming low-carbon development principles in new urban
56 development in all regions. Much of this development will be self-built and `informal' - and new modes of
57 governance and planning will be required to engage with this. Integrating mitigation and adaptation now

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 1 rather than later, through reshaping patterns of urban development and associated decision-making
 2 processes, is a prerequisite for attaining resilient and zero carbon cities.

 3

 4 While more cities have developed plans for climate adaptation and mitigation since AR5, many remain to be
 5 implemented (limited evidence, high agreement) (Araos et al., 2017; Olazabal and De Gopegui, 2021; Aguiar
 6 et al., 2018). A review of local climate mitigation and adaptation plans across 885 urban areas of the
 7 European Union suggests mitigation plans are more common than adaptation plans, and that city size,
 8 national legislation, and international networks can influence the development of local climate plans with an
 9 estimated 80% of cities with above 500,000 inhabitants having a mitigation and/or an adaptation plan
10 (Reckien et al., 2018b).

11

12 Integrated approaches to tackle common drivers of emissions and cascading risks provide the basis for
13 strengthening synergies across mitigation and adaptation and managing possible trade-offs with sustainable
14 development (limited evidence, medium agreement) (Grafakos et al., 2019; Landauer, Juhola and Klein,
15 2019). Analysis of 315 local authority emission reduction plans across the European Union reveals that the
16 most common policies cover municipal assets and structures (Palermo et al 2020). Estimates of emission
17 reductions by non-state and sub-state actors in ten high-emitting economies projected GHG emissions in
18 2030 would be 1.2­2.0 GtCO2e/year or 3.8%­5.5% lower compared to scenario projections for current
19 national policies (31.6­36.8 GtCO2e/year) if the policies are fully implemented and do not change the pace
20 of action elsewhere (Kuramochi et al 2020). The value of integrating mitigation and adaptation is
21 underscored in the opportunities for decarbonizing existing urban areas, and investing in social, ecological,
22 and technological infrastructure resilience (WGII 6.4). Integrating mitigation and adaption is challenging
23 (Landauer, Juhola and Klein, 2019) but can provide multiple benefits for the health and wellbeing of urban
24 inhabitants (Sharifi, 2020).

25

26 Effective climate strategies combine mitigation and adaptation responses, including through linking adaptive
27 urban land use with GHG emission reductions (medium evidence, high agreement) (Xu et al., 2019;
28 Patterson et al., 2021). For example, urban green and blue infrastructure can provide co-benefits for
29 mitigation and adaptation (Ürge-Vorsatz et al., 2018) and is an important entry point for integrating
30 adaptation and mitigation at the urban level (Frantzeskaki et al., 2019). Grey and physical infrastructure such
31 as sea defences can immediately reduce risk, but can also transfer risk and limit future options. Social policy
32 interventions including social safety nets provide financial security for the most at risk and can manage
33 vulnerability both determined by specific hazards or independently. Hazard independent mechanisms for
34 vulnerability reduction ­ such as population wide social security - provide resilience in the face of
35 unanticipated cascading impacts or surprise and novel climate related hazard exposure. Social interventions
36 can also support, or be led by ambitions to reach the Sustainable Development Goals (Archer, 2016).
37 Climate resilient development invites planners to plan interventions and monitor the effectiveness of
38 outcomes beyond individual projects and across wider remits that reach into sustainable development.
39 Curbing the emission impacts of urban activities to reach net zero in the next decades while improving the
40 resilience of urban areas necessitates an integrated response now.

41

42 Key gaps in knowledge include urban enabling environments; how smaller settlements, low-income
43 communities living in slums and informal settlements ­ but also those in rental housing spread across the
44 city; and actions to reduce supply chain risk can be supported to accelerate equitable and sustainable
45 adaptation in the face of financial and governance constraints (Birkmann et al., 2016; Shi et al., 2016; Dulal,
46 2019; Rosenzweig et al., 2018b).

47

48 Enabling Action

49

50 Innovative governance and finance solutions are required to manage complex and interconnected risks across
51 essential key infrastructures, networks and services and meet basic human needs in urban areas (medium
52 confidence) (Moser et al., 2019; Colenbrander, Dodman and Mitlin, 2018). There are many examples of
53 `ready-to-use' policy tools, technologies and practical interventions for policy makers seeking to act on
54 adaptation and mitigation (Keenan, Chu and Peterson, 2019; Bisaro and Hinkel, 2018; Chirambo, 2021). Tax
55 and fiscal incentives for business and individuals can help support city-wide change behaviour towards low
56 carbon and risk reducing choices. Change can start where governments have most control ­ in public sector
57 institutions and investment but the challenge ahead requires partnership with private sector and community

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 1 actors acting at scale and with accountability. Urban climate governance and finance needs to address urban
 2 inequalities at the forefront if the urban opportunity is to realise the ambition of the Sustainable Development
 3 Goals.

 4

 5 Increasing investment at pace will put pressure on governance capability and transparency and accountability
 6 of decision making (medium confidence) (WG II 6.6.4.5). Urban climate action that actively includes local
 7 actors and is built on an evidence base open to independent scrutiny is more likely to avoid unintended,
 8 negative maladaptive impacts and mobilise a wide range of local capacities. In the long-run this is also more
 9 likely to carry public support, even if some experiments and investments do not deliver the intended social
10 benefits. Legislation, technical capacity and governance capability is required to be able to absorb additional
11 finance. About US$ 384 billion of climate finance has been invested in urban areas per year in recent years.
12 This remains at about 10% of the annual climate finance that would be necessary for low-carbon and
13 resilient urban development (Negreiros et al., 2021). Rapid deployment of funds to stimulate economies in
14 recovery from COVID-19 have highlighted the pitfalls of funding expansion ahead of policy innovation and
15 capacity building. The result can be an intensification of existing urban forms ­ exactly the kinds of choices
16 and preferences that have contribute to risk creation and its concentration amongst those with little public
17 voice or economic power.

18

19 Iterative and experimental approaches to climate adaptation and mitigation decision-making co-generated in
20 partnership with communities, can advance climate resilient decarbonisation (medium evidence, high
21 agreement) (Caldarice, Tollin and Pizzorni, 2021; Culwick et al., 2019; van der Heijden and Hong, 2021).
22 Conditions of complexity, uncertainty and constrained resources require innovative solutions which are both
23 adaptive and anticipatory. Complex interactions among multiple agents in times of uncertainty makes
24 decision making about social, economic, governance, and infrastructure choices challenges and can lead
25 decision-makers to postpone action. This is the case for those balancing household budgets, residential
26 investment portfolios and city-wide policy responsibilities. Living with climate change requires changes to
27 business-as-usual design making. Codesign and collaboration with communities through iterative policy
28 experimentation can point the way towards climate resilient development pathways (Ataöv and Peker, 2021).
29 Key to successful learning is transparency in policy making, inclusive policy processes and robust local
30 modelling, monitoring and evaluation which are not yet widely undertaken (Ford et al., 2019; Sanchez
31 Rodriguez, Ürge-Vorsatz and Barau, 2018).

32

33 The diversity of cities' experiences of climate mitigation and adaptation strategies brings an advantage for
34 those city government and other actors willing to `learn together' (limited evidence, high agreement)
35 (Bellinson and Chu, 2019; Haupt and Coppola, 2019). While contexts are varied, policy options are often
36 similar enough for the sharing of experiments and policy champions. Sharing expertise can build on existing
37 regional and global networks, many of which have already placed knowledge, learning and capacity building
38 at the centre of their agendas. Learning from innovative forms of governance and financial investment, and
39 strengthening coproduction of policy through inclusive access to knowledge and resources, can help address
40 mismatches in local capacities, strengthen wider Sustainable Development Goals and COVID-19 Recovery
41 agendas (limited evidence, medium agreement). Perceptions of risk can greatly influence the reallocation of
42 capital and shift financial resources (Battiston et al., 2021). Coupling mitigation and adaptation in an
43 integrated approach offers opportunities to enhance efficiency, increases the coherence of urban climate
44 action, generates cost savings and provides opportunities to reinvest the savings into new climate action
45 projects to make all urban areas and regions more resilient.

46

47 Local governments play an important role in driving climate action across mitigation and adaptation as
48 managers of assets, regulators, mobilizers and catalysts of action, but few cities are undertaking
49 transformative climate adaptation or mitigation actions (limited evidence, medium agreement) (Heikkinen,
50 Ylä-Anttila and Juhola, 2019). Local actors are providers of infrastructure and services, regulators of zoning,
51 and can be conveners and champions of an integrated approach for mitigation and adaptation at multiple
52 levels 9Limited evidence high confidence). New opportunities in governance and finance can enable cities to
53 pool resources together and aggregate interventions to innovate ways of mobilizing urban climate finance at
54 scale (White and Wahbah, 2019; Simpson et al, 2019; Colenbrander et al, 2019). However, research
55 increasingly points towards the difficulties faced during the implementation of climate financing in situ, such
56 as for example, the fragmentation of structures of governance capable of managing large investments
57 effectively (Mohammed et al, 2019).

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1

2 Scaling up transformative place-based action for both adaptation and mitigation requires enabling conditions
3 including land-based financing, intermediaries and local partnerships (medium evidence, high agreement)

4 (Chaudhuri et. al, 2021, Tirumala and Tiwari, 2021(Chu et al., 2019). Governance structures that combine

5 actors working at different levels with different mix of tools are effective in addressing challenges related to
6 implementation of integrated action while cross-sectoral coordination is necessary (Singh et al., 2020). Joint
7 institutionalization of mitigation and adaptation in local governance structures can also enable integrated

8 action (Göpfert et al., 2020; Hurlimann et al., 2021). However, the proportion of international finance that

 9 reaches local recipients remains low, despite the repeated focus of climate policy on place-based adaptation
10 and mitigation (Manuamorn, 2019). Green financing instruments that enable local climate action without
11 exacerbating current forms of inequality can jointly address mitigation, adaptation and sustainable
12 development. Climate finance that also reaches beyond non-state enterprises, including SMEs, communities
13 and NGOs, and is responsive to the needs of urban inhabitants, including disabled individuals and different
14 races or ethnicities is essential for inclusive and resilient urban development (Colenbrander et al, 2019;
15 Gabaldon-Estevan et al, 2019; Frenova, 2020). Developing networks that can exert climate action at scale is
16 another priority for climate finance.

17

18 The urbanisation megatrend is an opportunity to transition global society. Enabling urban governance to
19 avert cascading risk and achieve low-carbon, resilient development will involve coproduction of policy and
20 planning, rapid implementation and greater cross sector coordination, monitoring and evaluation (limited

21 evidence, medium agreement) (Grafakos et al., 2019; Di Giulio et al., 2018). New constellations of

22 responsible actors are required to manage hybrid local-city or cross-city risk management and
23 decarbonisation initiatives (limited evidence, medium agreement). These may increasingly benefit from
24 linkages across more urban and more rural space as recognition of cascading and systemic risk brings

25 recognition of supply chains, remittance flows and migration trends as vectors of risk and resilience. Urban

26 governance will be better prepared in planning, prioritizing and financing the kind of measures that can
27 reduce GHG emissions and improve resilience at scale and pace when considering a view of cascading risks
28 and carbon lock-ins globally, while acting locally to address local limitations and capacities, including the
29 needs and priorities of urban citizens (Udelsman Rodrigues, 2019; Colenbrander et al, 2018).

30

31 [END CROSS-WORKING GROUP BOX URBAN HERE]

32

33

34 [START FAQ6.1 HERE]

35

36 FAQ6.1: Why and how are cities, settlements, and different types of infrastructure especially

37  vulnerable to the impacts of climate change?

38

39 Cities, settlements and infrastructure become vulnerable when investment decisions fail to take the risks of
40 climate change fully into account. Such failures can result from a lack of understanding, competing

41 priorities, a lack of finance or access to appropriate technology. Around the world, smaller cities and poorer

42 populations are often most vulnerable and suffer the most over time, while large cities can register the

43 greatest losses to individual events.

44

45 The world is urban. Billions of people live in towns and cities. Hardly anyone, even in remote rural

46 locations, is separated from the flows of trade that connect the world and are held together by networks of
47 transport and communication infrastructure systems. Connected networks once broken can cascade out,
48 multiplying impacts across urban and rural areas. When major manufacturing centres or regionally important
49 ports are impacted, global trade suffers. For example, flooding in Bangkok in 2011 led to a global shortage
50 in semiconductors and a slowdown in the global computer manufacturing.

51

52 Despite cities generating wealth, additional vulnerability to climate change is being created in urban areas
53 every day. Demographic change, social and economic pressures and governance failures that drive inequality
54 and marginality mean that increasing numbers of people who live in towns and cities are exposed to

55 flooding, temperature extremes and water or food insecurity. This leads to an adaptation gap, where rich

56 neighbourhoods can afford strategies to reduce vulnerability while poorer communities are unable to do the
57 same. Although this would be so even without a changing climate, climate change increases the variability

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1 and extremes of weather, exposing more people, businesses and buildings to floods and other events. The
2 combination of rising vulnerability and increasing exposure translates to a growth in the number of people
3 and properties at risk from climate change in cities worldwide.

4

5 Around the world, vulnerability is rising but differs considerably between and within urban areas.
6 Settlements of up to 1 million people are the most rapidly expanding and also amongst the most vulnerable.
7 These settlements often have limited community level organisation and might not have a dedicated local

8 government. Coping with rapid population growth under conditions of climate change and constrained

 9 capacity is a major challenge. For large cities, multiple local governments and well organised community-
10 based organisations interact with large businesses and national political parties in a complicated cocktail of
11 interests that can interfere with planning and action to reduce vulnerability.

12

13 For the poorest living in urban slums, informal settlements or renting across the city, lack of secure tenure
14 and inadequate access to basic services compound vulnerability. But even the wealthy in large cities are not
15 fully protected from climate change related shocks. Just like breaks in infrastructure between towns and rural
16 settlements, big city infrastructure can be broken by even local landslides, floods or temperature events with
17 consequences cascading across the city. Electricity blackouts are the most common and can affect water

18 pumping, traffic regulation, streetlights as well as hospitals, schools and homes. Still, it is the urban poor and
19 marginalised who experience the greatest exposure, most vulnerability and least capacity to cope.

20

21 Rounds of exposure and impact can reduce the capacity of survivors to cope with future events. As a result,

22 the already vulnerable and exposed become more vulnerable over time, increasing urban inequalities. But
23 this need not be the case. Focussing on vulnerability reduction is not easy, it requires joined up action across
24 social and economic development sectors together with critical infrastructure planning. It often also means

25 partnering local government with informal and community-based actors. But there is considerable

26 experience globally on what works and how to deliver reduced vulnerability for the urban poor and for cities
27 as a whole. The challenge is to scale up this experience and accelerate its application to keep pace with
28 climate change and address the adaptation gap.

29

30 [END FAQ6.1 HERE]

31

32

33 [START FAQ6.2 HERE]

34

35 FAQ6.2: What are the key climate risks faced by cities, settlements, and vulnerable populations today,

36  and how will these risks change in a mid-century (2050) 2°C warmer world?

37

38 Climate change will interact with the changing physical environment in cities and settlements to create or

39 exacerbate a range of risks. Rising temperatures and heat waves will cause human illness, morbidity as well
40 as infrastructure degradation and failures, while heavy rainfall and sea-level rise will worsen flooding. Low-

41 income groups and other vulnerable populations will be affected most severely because of where they live

42 and their limited ability to cope with these stresses.

43

44 Cities and settlements are constantly changing. Their populations grow and shrink, economic activities
45 expand or decline, and political priorities shift. The risks that cities and their residents face are influenced by

46 both urban change and climate change. The seriousness of these risks into the 21st Century will be shaped by
47 the interactions between drivers of change including population growth, economic development and land use
48 change.

49

50 In a warming world, increasing air temperature makes the Urban Heat Island effect in cities worse. One key

51 risk is heat waves in cities that are likely to affect half of the future global urban population with negative
52 impacts on human health and economic productivity. Heat and built infrastructure such as streets and houses
53 interact with each other and magnify risks in cities. For instance, higher urban temperatures can cause
54 infrastructure to overheat and fail, as well as increase the concentration of harmful air pollutants such as

55 ozone.

56

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1 The density of roads and buildings in urban areas increases the area of impermeable surfaces, which interact
2 with more frequent heavy precipitation events to increase the risk of urban flooding. This risk of flooding is
3 greater for coastal settlements due to sea level rise and storm surges from tropical cyclones. Coastal

4 inundation in the Miami-Dade region in Florida, USA, is estimated to have caused over USD465 million in

5 lost real estate value between 2005 and 2016, and it is likely that coastal flood risks in the region beyond
6 2050 will increase without adaptation to climate change.

7

8 Within cities, different groups of people can face different risks. Many low-income residents live in informal

 9 settlements alongside coasts or rivers, which greatly heightens exposure and vulnerability to climate-driven
10 hazards. In urban areas in Ghana, for example, risks from urban flooding can compound health risks, and
11 have resulted in outbreaks of malaria, typhoid and cholera. Those outbreaks have been shown to
12 disproportionately affect poorer communities.

13

14 Severe risks in cities and settlements also arise from reduced water availability. As urban areas grow, the
15 amount of water required to meet basic needs of people and industries increases. When increased demand is
16 combined with water scarcity from lower rainfall due to climate change, water resource management
17 becomes a critical issue. Low-income groups already face major challenges in accessing water, and the

18 situation is likely to worsen due to growing conflicts over scarce resources, increasing water prices, and
19 diminishing infrastructure provisions in ever-expanding informal settlements.

20

21 These key risks already differ greatly between cities, and between different groups of people in the same

22 city. By 2050 these discrepancies are likely to be even more apparent. Cities with limited financial resources,
23 regulatory authority and technical capacities are less equipped to respond to climate change. People who
24 already have fewer resources and constrained opportunities face higher levels of risk because of their

25 vulnerability. As a result of this, key risks vary not only over time as climate change is felt more strongly.

26 They also vary over space ­ between cities exposed to different hazards and with different abilities to adapt ­
27 and between social groups, meaning between people who are more or less affected and able to cope.

28

29 [END FAQ6.2 HERE]

30

31

32 [START FAQ6.3 HERE]

33

34 FAQ6.3: What adaptation actions in human settlements can contribute to reducing climate risks and

35  building resilience across building, neighbourhood, city, and global scales?

36

37 Settlements bring together many activities, so climate action will be most effective if it is integrated and

38 collaborative. This requires (i) embedding information on climate change risks into decisions; (ii) building

39 capacity of communities and institutions; (iii) using both nature-based and traditional engineering
40 approaches; (iv) working in partnership with diverse local planning and community organisations; and, (v)

41 sharing best practice with other settlements.

42

43 Settlements bring together people, buildings, economic activities and infrastructure services, and thus
44 integrated, cross-sector, adaptation actions offer the best way to build resilience to climate change impacts.
45 For example, actions to manage flood risk include installing flood proofing measures within and outside

46 properties, improving capacity of urban drainage along roads, incorporating nature-based solutions within
47 the urban areas, constructing flood defences, and managing land upstream of settlements to reduce runoff.

48

49 Adaptation actions will be more effective if they are implemented in partnership with local communities,
50 national governments, research institutions, and the private and third sector. Climate action should not be

51 considered as an additional or side action to other activities. Rather, climate action should be mainstreamed
52 into existing processes, including those that contribute to the UN Sustainable Development Goals (2015) and
53 New Urban Agenda adopted at the UN Conference on Housing and Sustainable Urban Development (Habitat
54 III) in 2016. Cities are already coming together through international networks to share good practice about

55 adaptation actions, speeding up the dissemination of knowledge.

56

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1 This integrated approach to adaptation in human settlements needs to be supported by various other actions,
2 including potential co-benefits with carbon emissions reductions, public health, and ecosystem conservation
3 goals. First, information on climate risks needs to be embedded into the architectural design, delivery and

4 retrofitting of housing, transportation, spatial planning and infrastructure across neighbourhood and city

5 scales. This includes making information on climate impacts widely available, updating design standards,
6 and strengthening regulation to avoid development in high-risk locations. Second, the capacity of
7 communities needs to be strengthened, especially amongst those in informal settlements, the poorest and

8 other vulnerable groups including minorities, migrants, women, children, elderly, disabled, and people with

 9 serious health conditions such as obesity. This involves raising awareness, incorporating communities into
10 adaptation processes, and strengthening regulation, policies and provision of infrastructure services. Third,
11 nature-based solutions should be integrated to work alongside traditional `grey' or engineered infrastructure.
12 Vegetation corridors, greenspace, wetlands and other green infrastructure can be woven into the built
13 environment to reduce heat and flood risks, whilst providing other benefits such as health and biodiversity.

14

15 Although even the largest city covers only a small area of the planet, all settlements are part of larger
16 catchments from which people, water, food, energy, materials, and other resources support them. Actions
17 within cities should be mindful of wider impacts and avoid displacing issues elsewhere.

18

19 [END FAQ6.3 HERE]

20

21

22 [START FAQ6.4 HERE]

23

24 FAQ6.4: How can actions that reduce climate risks in cities and settlements also help to reduce urban

25  poverty, enhance economic performance, and contribute to climate mitigation?

26

27 If carefully planned, adaptation actions can reduce exposure to climate risk as well as reduce urban poverty,
28 advance sustainable development and mitigate greenhouse gas emissions. When adaptation responses are
29 equitable, and if a range of voices are heard in the planning process, the needs of the disadvantaged are
30 more likely to be addressed and wider societal benefits can be maximized.

31

32 Urbanization is a global trend which is interacting with climate change to create complex risks in cities and
33 settlements, especially for those that already have high levels of poverty, unemployment, housing

34 informality, and backlogs of services. Many cities and settlements are seeing increasing action to manage
35 climate risks. On top of reducing communities' exposure to climate risk, adaptation actions can have benefits
36 for reducing urban poverty and enhancing economic performance in ways that reduce inequality and advance
37 sustainability goals. Adaptation actions, however, can also have unintended consequences. That is why care

38 needs to be taken to ensure climate adaptation planning and development of new infrastructure does not

39 exacerbate inequality or negatively impact other sustainable development priorities. Climate adaptation
40 planning is most effective when it is sensitive to the diverse ways that low-income and minority communities

41 are more likely to experience climate risk, including women, children, migrants, refugees, internally

42 displaced peoples, racial/ethnic minority groups, among others.

43

44 Adapting to climate change can have benefits for reducing greenhouse gas emissions and urban inequalities.
45 In cities where growing numbers of people live in informal settlements, introducing risk-reducing physical

46 infrastructure such as piped water, sanitation, drainage systems can enhance the quality of life of the
47 community. At the same time, those measures can increase health outcomes and reduce urban inequalities by
48 reducing exposure to flooding or heat impacts. In less developed countries, less than 60% of the urban
49 population have access to piped water which, in turn, impacts their health and well-being. Increasingly,
50 housing is being built better to manage heat risk through insulation, changing building orientation or to flood

51 risk by raising structures, which then contributes to wellbeing and ability to work. Improvements to early
52 warning systems can help people evacuate rapidly in case of storm surges or flooding. Although the most
53 vulnerable often do not get these warnings in time.

54

55 Carefully planned nature-based solutions, such as public green space, improved urban drainage systems and

56 storm water management, can deliver both health and development benefits. When these adaptation actions
57 succeed, water, waste and sanitation can be improved to better manage climate risk and provide households

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1 and cities with better services. Many nature-based solutions entail bringing back plants and trees into cities
2 which also helps to reduce the concentration of heat-trapping greenhouse gases in the atmosphere.

3

4 When care is taken to ensure that adaptation responses are equitable, and that a range of voices are heard in

5 planning, the needs of the disadvantaged are more likely to be addressed. For example, a study that looked at
6 transport plans across 40 cities in Portugal saw that some urban communities have prioritised the needs of
7 disadvantaged users such as the elderly and disabled, while at the same time reducing urban transport

8 emissions while enhancing public wellbeing and equity of transport. On the other hand, in some cities, there

 9 is evidence of emerging trade-offs associated with climate adaptation actions where sea walls and temporary
10 flood barriers were erected in economically valuable areas and not is less well-off areas. Going forward, it is
11 important to ensure that vulnerable groups' needs are carefully considered both in terms of climate and other
12 risks as this has not been sufficiently done in the past.

13

14 [END FAQ6.4 HERE]

15

16

17 [START FAQ6.5 HERE]

18

19 FAQ6.5: What policy tools, governance strategies, and financing arrangements can enable more

20  inclusive and effective climate adaptation in cities and settlements?

21

22 Inclusive and effective climate adaptation requires efforts are all levels of governance, including the public
23 sector, the private sector, the third sector, communities and intermediaries such as universities or think
24 tanks. Inclusive and effective adaptation requires action fit for the diverse conditions in which it is needed.

25 Collaborative dialogues can help to map both adaptation opportunities and potential negative impacts.

26

27 There is no one-size-fits-all approach to ensure that climate adaptation efforts have positive results and
28 include the concerns of everyone affected. Cities and local communities are diverse, and thus they have
29 diverse perspectives on what responses to prioritize. Moreover, adaptation efforts may impact people's lives
30 in very different ways. Policy tools, strategies and financial arrangements for adaptation can include all
31 society sectors and address socio-economic inequalities. Planning and decision-making must respond to
32 marginalized voices and future generations (including children and youth).

33

34 Efforts to adapt to climate change can be incremental, reformist, or transformational, depending on the scale
35 of the change required. Incremental action may address specific climate impacts in a given place, but do not
36 challenge the social and political institutions that prevent people from bouncing back better. Reformist action
37 may address some of the social and institutional drivers of exposure and vulnerability, but without

38 addressing the underlying socio-economic structures that drive differential forms of exposure. For example,

39 social protection measures may improve people's capacity to cope with climate impacts, but that improved
40 capacity will depend on maintaining such protection measures. Transformative action involves fundamental

41 changes in political and socio-economic systems, oriented towards addressing vulnerability drivers (e.g.,

42 socio-economic inequalities, consumption cultures). All forms of adaptation are relevant to deliver resilient

43 futures because of the variability of conditions in which adaptation action is needed.

44

45 Local and regional governments play an essential role in delivering planning and institutional action suited to

46 local conditions in cities and settlements. Potential strategies can span multiple sectors and scales, ranging
47 from land use management, building codes, critical infrastructure designs and community development
48 actions, to different legal, financial, participatory decision-making and robust monitoring and evaluation
49 arrangements. NGOs or third sector organisations can also play a coordinating role by building dialogues
50 across governments, the private sectors, and communities through effective communication and social

51 learning. Local action tends to falter without the support of national governments as they are often
52 facilitators of resources and finance. They can create institutional frameworks that facilitate (rather than
53 impede) local action. National governments also play a crucial role in the development of large-scale
54 infrastructures.

55

56 Private actors can also drive adaptation action. The evaluation of private-led infrastructure and housing
57 projects suggests that the prioritization of profit, however, may have a detrimental impact on the overall

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 1 resilience of a place. New institutional models such as public-private partnerships respond to the
 2 shortcomings of both the public and private sectors. Still, the evidence of them facilitating the inclusion of
 3 multiple actors is mixed.

 4

 5 The private sector can mobilize finance. However, the forms of finance available for adaptation are limited
 6 and directed to huge projects that do not always address local adaptation needs. Private actors tend to join
 7 adaptation projects when there is an expectation of large profits, such as in interventions that increase real
 8 estate value. Private-led adaptation can lead to `gentrification' whereby low-income populations are
 9 relocated from urban centres and safer settlements. Models that enable the collaboration between public,
10 private and civil society sectors have greater potential to mobilise adaptation finance in inclusive ways.

11

12 Forms of collaborative planning and decision-making can create dialogues for a sustainable future in cities,
13 settlements and infrastructure systems. Adaptation action needs multiple approaches. For example,
14 adaptation needs both actions that depend on dialogues between multiple actors (e.g., urban planning and
15 zoning) and action that follows strong determination and leadership (e.g., declarations of emergency and
16 target commitments). There are adaptation actions that depend on place-based conditions (e.g., flood
17 defences) and those that require considering interactions across scales (e.g., regulatory frameworks). The
18 growth of adaptation capacities, fostering dialogues, empowered communities, multi-scalar assessments, and
19 foresight within current institutions can support effective and inclusive adaptation action that is also
20 sustained in the long term.

21

22 [START FAQ6.5 HERE]

23

24

25

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