FINAL DRAFT Cross-Chapter Paper 5 IPCC WGII Sixth Assessment Report
1
2 Cross-Chapter Paper 5: Mountains
3
4 Cross-Chapter Paper Leads: Carolina Adler (Switzerland/Chile/Australia), Philippus Wester (Nepal/The
5 Netherlands)
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7 Cross-Chapter Paper Authors: Indra Bhatt (India), Christian Huggel (Switzerland), Gregory Insarov
8 (Russian Federation), Michael Morecroft (United Kingdom), Veruska Muccione (Switzerland/Italy), Anjal
9 Prakash (India)
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11 Cross-Chapter Paper Contributing Authors: Irasema Alcántara-Ayala (Mexico), Simon K. Allen
12 (Switzerland/New Zealand), Maaike Bader (Germany), Sophie Bigler (Switzerland), James Camac
13 (Australia), Ritodhi Chakraborty (New Zealand/India), Aida Cuni Sanchez (Norway/Spain), Nicolás Cuvi
14 (Ecuador), Fabian Drenkhan (Peru/Germany), Abid Hussain (Nepal/Pakistan), Amina Maharjan (Nepal),
15 Robert Marchant (United Kingdom), Graham McDowell (Canada/USA), Samuel Morin (France), Laura
16 Niggli (Switzerland), Ana Ochoa (Ecuador), Avash Pandey (Nepal), Julio Postigo (USA/Peru), Estelle
17 Razanatsoa (South Africa/Madagascar), Valeria M. Rudloff (Chile), Christopher Scott (USA), Madison
18 Stevens (Canada), Daithi Stone (New Zealand), Jessica Thorn (United Kingdom/Namibia), James Thornton
19 (Switzerland/United Kingdom), Daniel Viviroli (Switzerland), Saskia Werners (The Netherlands)
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21 Cross-Chapter Paper Review Editor: Georg Kaser (Austria)
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23 Cross-Chapter Paper Scientist: Valeria M. Rudloff (Chile)
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25 Date of Draft: 1 October 2021
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27 Notes: TSU Compiled Version
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29
30 Table of Contents
31
32 Executive Summary..........................................................................................................................................3
33 CCP5.1 Point of Departure ........................................................................................................................6
34 CCP5.2 Observed Impacts and Adaptation in Mountain Social-Ecological Systems...........................7
35 CCP5.2.1 Ecosystems and Ecosystem Services ......................................................................................7
36 Box CCP5.1: Wildfires and Mountain Ecosystems .......................................................................................9
37 CCP5.2.2 Water and Energy .................................................................................................................11
38 CCP5.2.3 Food, Fibre, and Other Mountain Ecosystem Products ........................................................14
39 CCP5.2.4 Cities, Settlements and Key Infrastructure ...........................................................................16
40 CCP5.2.5 Mountain Communities, Livelihoods, Health and Wellbeing ..............................................17
41 CCP5.2.6 Natural Hazards and Disasters ..............................................................................................21
42 CCP5.2.7 Synthesis of Observed Impacts and Attribution and Observed Adaptation .........................22
43 CCP5.3 Projected Impacts and Risks in Mountains..............................................................................25
44 CCP5.3.1 Synthesis of Projected Impacts .............................................................................................25
45 CCP5.3.2 Key Risks Across Sectors and Regions ................................................................................26
46 CCP5.4 Options for Adaptation and Climate Resilient Development Pathways................................31
47 CCP5.4.1 Synthesis of Adaptation Responses to Reducing (Key) Risks..............................................31
48 CCP5.4.2 Challenges, Opportunities and the Solution Space for Adaptation in Mountains ................32
49 CCP5.4.3 Climate Resilient and Sustainable Development in Mountains............................................34
50 CCP5.5 Key Assessment Limitations and Relevant Knowledge Gaps.................................................35
51 FAQ CCP5.1: How is freshwater from mountain regions affected by climate change, and what are the
52 consequences for people and ecosystems? ............................................................................................37
53 FAQ CCP5.2: Are people in mountain regions, and further downstream, facing more severe risks to
54 water-related disasters due to climate change, and how are they coping? .......................................38
55 FAQ CCP5.3: Is climate change a risk to mountain species and ecosystems, and will this affect people?
56 ....................................................................................................................................................... 39
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1 FAQ CCP5.4: What type of adaptation options are feasible to address the impacts of climate change in
2 mountain regions under different levels of warming, and what are their limits? ............................40
3 FAQ CCP5.5: Why regional cooperation and transboundary governance is needed for sustainable
4 mountain development? .........................................................................................................................41
5 References .......................................................................................................................................................43
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7
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FINAL DRAFT Cross-Chapter Paper 5 IPCC WGII Sixth Assessment Report
1 Executive Summary
2
3 Mountains are highly significant regions in the context of climate change and sustainable development, at the
4 intersection of accelerated warming and a large population depending directly or indirectly on them. They
5 are regions of high biological and cultural diversity and provide vital goods and services to people living in
6 and around mountain regions and in downstream areas. Building on the IPCC's Fifth Assessment Report
7 (AR5), Chapter 2 "High Mountain Areas" of the Special Report on the Ocean and Cryosphere in a Changing
8 Climate (SROCC), and the IPCC Working Group I contribution to AR6, this Cross-Chapter Paper (CCP)
9 assesses new evidence on observed and projected climate change impacts in mountain regions, their
10 associated key risks and adaptation measures.
11
12 Observed changes, their impacts, and adaptation responses in mountains
13
14 Climate change impacts in mountains and their attribution to human influence have increased in
15 recent decades with observable and serious consequences for people and ecosystems in many mountain
16 regions (high confidence1). Observed changes include increasing temperatures, changing seasonal weather
17 patterns, reductions in snow cover extent and duration at low elevation, loss of glacier mass, increased
18 permafrost thaw, and an increase in the number and size of glacier lakes (high confidence). {CCP5.2.7,
19 Figure CCP5.4, SROCC Chapter 2, WGI Section 9.5}
20
21 The spatial distributions of many plant species have shifted to higher elevations in recent decades,
22 consistent with rising temperatures across most mountain regions (high confidence). Around two-thirds
23 of treeline ecotones have also shifted upwards in recent decades, though these shifts are not ubiquitous and
24 slower than expected based on rising temperatures (high confidence). Impacts on biological communities and
25 animal species are also increasingly being reported, with species of lower elevations increasing in mountain
26 regions, creating more homogeneous vegetation and increasing risks to mountain top species (medium
27 confidence). {CCP5.2.1; Chapter 2.4}
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29 Climate and cryosphere change have negatively affected the water cycle in mountains, including
30 variable timing of glacier- and snow-melt stream discharge (high confidence). These changes have
31 variable impacts on water availability for people and economies, contributing to increasing tensions or
32 conflicts over water resources, especially in seasonally dry regions (medium confidence). Mountains are
33 an essential source of freshwater for large, and growing populations; the number of people largely or fully
34 dependent on water from mountains has increased worldwide from ~0.6 billion in the 1960s to ~2 billion in
35 the past decade and globally two-thirds of irrigated agriculture depends on essential runoff contributions
36 from the mountains. {CCP5.2.2; Figure CCP5.2; SROCC Chapter 2; 4.2.2.3; 4.4.4.1}
37
38 Climate change-driven changes in precipitation, river flow regimes and landslides affect the
39 production and use of energy in mountain regions, in particular hydropower (high confidence).
40 Billions of USD in investment and assets of energy production are exposed to changing mountain hazards.
41 Combined effects of climate change, hydropower development and other human interventions have
42 exacerbated water security problems and social injustice (medium confidence). {CCP5.2.2, SROCC Chapter
43 2}
44
45 Observed climate-driven impacts on mountain ecosystem services, agriculture and pastoralism are
46 largely negative in most mountain regions (medium confidence). Agriculture has been negatively affected
47 through increased exposure to hazards such as droughts and floods, changes in the onset of seasons, the
48 timing and availability of water, increasing pests and decreasing pollinator diversity, which in turn have
49 negatively influenced overall production, dietary diversity and nutritional value (medium confidence).
50 Negative climate impacts on pastoralism, such as drought induced degradation of rangelands and pastures,
51 have affected livestock productivity and livelihood of pastoralists, while other non-climatic factors such as
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 land-use change and management also play a role (medium confidence). {CCP5.2.3; CCP5.2.5; Table
2 CCP5.2; SROCC Section 2.3.1.3.2; SROCC Section 2.3.7}
3
4 While contributing to poverty reduction in some mountain regions, there is limited evidence of
5 adaptations effectively contributing to remediating the underlying social determinants of vulnerability
6 such as gender and ethnicity (medium confidence). Exposure and vulnerability exacerbate the negative
7 effects of climate impacts on livelihoods, and intertwines with power imbalances, gender and other
8 inequalities (medium confidence). {CCP5.2.7; CCP5.3.2.2}
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10 Observed changes in seasonality (timing and extent) are negatively affecting mountain winter tourism
11 and recreation (high confidence), and variably affect tourism and recreation activities in other seasons
12 (medium confidence). For winter activities such as skiing, diminishing snow at lower elevations has
13 challenged their operating conditions (medium confidence), increasing the demand for and dependence on
14 snow management measures such as snow-making (high confidence). Climate-induced hazards are
15 negatively affecting some climbing, mountaineering, and hiking routes (medium confidence). In some
16 regions, options to change routes or shift seasons to reduce hazard exposure have been employed as
17 adaptation strategies, with variable outcomes (medium confidence). In some cases, higher temperatures and
18 extreme heatwave conditions at lower elevations have made some mountain destinations more appealing,
19 increasing the potential for summer visitation demand (medium confidence). {CCP5.2.5; Table CCP5.2;
20 SROCC Ch2.3.5}
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22 Climate-related hazards, such as flash floods and landslides, have contributed to an increase in
23 disasters affecting a growing number of people in mountain regions and further downstream (high
24 confidence). The resulting number of disasters has increased, however there is limited evidence that this is
25 due to changes in the underlying hazard processes, pointing mainly to increasing levels of exposure (medium
26 confidence). {CCP5.2.6; CCP5.2.7; CCP5.3.2.1}.
27
28 Adaptation responses to climate-driven impacts in mountain regions vary significantly in terms of
29 goals and priorities, scope, depth and speed of implementation, governance and modes of decision-
30 making, and the extent of financial and other resources to implement them (high confidence). Observed
31 adaptation responses in mountains are largely incremental and mainly focus on early warning systems and
32 the diversification of livelihood strategies in smallholder agriculture, pastoralism, and tourism. However,
33 there is limited evidence of the feasibility and long-term effectiveness of these measures to address climate-
34 related impacts and related losses and damages, including in cities and settlements experiencing changing
35 demographics. {CCP5.2.4; CCP5.2.7.2}
36
37 Projected impacts, key risks and limits to adaptation in mountains
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39 Increasing temperatures will continue to induce changes in mountain regions throughout the 21st
40 century, with expected negative consequences for mountain cryosphere, biodiversity, ecosystem
41 services and human wellbeing (very high confidence). Many low elevation and small glaciers around the
42 world will lose most of their total mass at 1.5°C GWL (high confidence). A large majority of endemic
43 mountain species will be at risk of extinction; regions heavily relying on glacier- and snow-melt for
44 irrigation will face erratic water supply and increased food insecurity, whereas agriculture in some regions
45 might see positive changes. Damages and losses from water related hazards such as floods and landslides are
46 projected to increase considerably between 1.5 and 3° GWL. {CCP5.3.1}
47
48 Projected changes in hazards, such as floods and landslides, as well as changes in the water cycle, will
49 lead to severe risk consequences for people, infrastructure and the economy in many mountain regions
50 (high confidence). These risks will be more pervasive and also increase more rapidly in South and Central
51 Asia and Northwestern South America. However, nearly all mountain regions will face at least moderate and
52 some regions even high risks at around 2°C GWL (medium confidence). {CCP5.3.2.1, CCP5.3.2.2; 16.B.4}
53
54 There is an increasing risk of local and global species extinctions where they are not able to move to
55 higher elevations or other cooler locations (high confidence), with risks from extreme events such as
56 wildfire potentially exacerbating those risks (medium confidence). The topographic variation in
57 mountains may mean that some species can survive in cooler microclimates with aspect as well as elevation.
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FINAL DRAFT Cross-Chapter Paper 5 IPCC WGII Sixth Assessment Report
1 Mountain regions may act as refugia for some species from lower elevations, if they can move into them.
2 This may enable some species to persist in a region, although it can present a threat to cold-adapted species,
3 including endemics, which may be outcompeted (high confidence); invasive non-native species may become
4 an increasing problem in some places. {CCP5.3.2.3, Box CCP5.1; CCP1.2.2.1; 2.6.6; 16.6.3.1}
5
6 Climate change is projected to lead to profound changes and irreversible losses in mountain regions
7 with negative consequences for ways of life and cultural identity (medium confidence). Intangible losses
8 and loss of cultural values will become increasingly more widespread in mountain regions mainly driven by
9 a decline in snow and ice and an increase in intangible harm to people from hazards (medium confidence).
10 However, there is limited evidence on the magnitude of the consequences. {CCP5.3.2.4; 16.5.2.1; 16.5.2.3.7}
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12 Options for future adaptation and climate resilient sustainable development in mountains
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14 The current pace, depth and scope of adaptation is insufficient to address future risks in mountain
15 regions, particularly at higher warming levels (high confidence). While the incremental nature of most
16 implemented adaptations will not be sufficient to reduce severe risk consequences, options exist which offer
17 practical and timely prospects to address risks before limits to adaptation are reached or exceeded. Reducing
18 climate risks will depend on addressing the root causes of vulnerability, which include poverty,
19 marginalization, and inequitable gender dynamics (high confidence). {CCP5.4.1, Figure CCP5.7: CCP5.4.2,
20 Cross-Chapter Box DEEP in Chapter 17; Cross-Chapter Box LOSS in Chapter 17; 17.3, 17.6}
21
22 Adaptation decision-making processes that engage with and incorporate people's concerns and values
23 and address multiple risks are more robust than those with a narrow focus on single risks (medium
24 confidence). Risk management strategies that better integrate the adaptation needs of all affected sectors,
25 account for different risk perceptions and build on multiple and diverse knowledge systems, including
26 Indigenous knowledge and local knowledge, are important enabling conditions to reduce risk severity
27 (medium confidence). {CCP5.2.6, CCP5.4.2; 17.3; 17.4; Cross-Chapter Box PROGRESS in Chapter 17;
28 Cross-Chapter Box DEEP in Chapter 17}
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30 Regional cooperation and transboundary governance in mountain regions, supported by multi-scale
31 knowledge networks and monitoring programmes, enable long-term adaptation actions where risks
32 transcend boundaries and jurisdictions (medium confidence). Collectively, they show potential to form
33 an important component of the adaptation solution space in mountains. There are increasing calls for more
34 ambitious climate action in mountains, providing impetus for stronger cooperation within and across
35 mountain regions, and downstream areas (medium confidence). {CCP5.4.2; CCP5.4.3}
36
37 With warming above 1.5oC, the need for adaptation to address key risks in mountains becomes
38 increasingly urgent (high confidence). Pathways and system transitions that strengthen climate-resilient
39 sustainable mountain development are starting to receive attention, but current levels of resourcing are
40 substantially insufficient to support timely action. {CCP5.4.2; CCP5.4.3; CCP5.5; 18.1; 18.2}
41
42
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FINAL DRAFT Cross-Chapter Paper 5 IPCC WGII Sixth Assessment Report
1 CCP5.1 Point of Departure
2
3 Mountains are an extensive and significant typological region (Section 1.3.3 and AR6 Glossary) in the
4 context of climate change and sustainable development, with a large population directly or indirectly
5 depending on mountains. These are areas of high biological and cultural diversity that provide vital goods
6 and services such as water, food, energy, minerals, medicinal plants, tourism and recreation, and aesthetic
7 and spiritual values to people living in and around these mountain regions and in downstream areas.
8 Mountain regions are hotspots of climate related losses in, for example, ecosystems, landscapes, culture, and
9 habitability, and while mountain people are adaptive, resourceful, and independent, they live in highly fragile
10 environments and in some regions under challenging socioeconomic circumstances that enhance their
11 vulnerability to climate change (Alfthan et al., 2018).
12
13 Chapter 2 "High Mountain Areas" (Hock et al., 2019) of the IPCC Special Report on the Ocean and the
14 Cryosphere in a Changing Climate (SROCC), presented an assessment of observed changes in the high
15 mountain cryosphere, their resulting impacts in-situ and further downstream, and the state of adaptation
16 responses to these impacts. Before SROCC, the last time climate change in mountain regions were
17 systematically assessed in IPCC reports was in Chapter 5 of the Second Assessment Report (SAR) (Beniston
18 et al., 1996). Projections made at the time for climate-related changes in mountain regions were expected
19 towards the middle and the second half of the twenty-first century, rather than as early as the past decades
20 (Haeberli and Beniston, 2021), underscoring the striking pace of change already observed in mountain
21 regions.
22
23 Whereas SROCC focused on impacts from a changing climate on high mountain cryosphere, this Cross-
24 Chapter Paper (CCP) on "Mountains" synthesizes key relevant content from across the AR6 WGII report
25 with a broader scope on the impacts and adaptation to climate change in mountain regions as defined for this
26 assessment (Figure CCP5.1, SMCCP5.1). It provides a wider assessment of the solutions space and
27 consequences for sustainable development due to climate change in mountain regions and downstream areas.
28
29 To define the geographical scope of the assessment in this CCP and to quantify the human population
30 residing within these regions, the mountain characterization given by Kapos et al. (2000) (Figure CCP5.1a
31 and SMCCP5.1), minus Antarctica, Svalbard and Greenland (which fall under the assessment scope of CCP6
32 Polar Regions), was employed. This characterization is consistent with the mountain region extents used in
33 the AR6 WGI report (see AR6 WGI Atlas) and yields a global mountainous area of 31.74 million km2,
34 which corresponds to approximately 23.5% of the global land surface. In 2015, a total of 1.28 billion people
35 resided in mountain regions as delineated for this CCP (SMCCP5.1).
36
37 The scope of the assessment presented in this CCP covers observed and projected climate change impacts in
38 mountains, present, emerging and future key risks and observed adaptation responses, leading to an
39 exploration of the adaptation solution space and climate-resilient development (pathways) in mountains.
40 Section 5.2 presents observed impacts and adaptation responses by synthesizing information on mountains in
41 the sectorial and regional chapters of WGII AR6, additional supporting evidence found in the literature, a
42 Detection and Attribution assessment (SMCCP5.2) and a reanalysis of the mountain literature collected and
43 synthesised in the Global Adaptation Mapping Initiative (GAMI) (SMCCP5.3). Section 5.3 presents an
44 assessment of future key risks in mountains drawing from the regional and sectorial chapters and a key risks
45 assessment for this CCP (SMCCP5.4). Section 5.4 explores the solution space for future adaptation
46 opportunities and constraints as well as climate resilient development in mountains. This CCP concludes
47 with key assessment limitations and knowledge gaps and prospects to address these gaps in Section 5.5.
48
49
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1
2 Figure CCP5.1: Delineation of mountain regions in CCP Mountains, population numbers and densities in 2015, and
3 their projections to 2100. a) Population in mountain regions in 2015 aggregated per IPCC WGII Continental Regions,
4 considering population densities, mountain areas and total population in mountain regions. b) Population projections in
5 mountain regions by 2100 for different Shared Socioeconomic Pathways (SSP) scenarios. c) Projected changes in
6 population in mountain regions from 2015 to 2100 across five different SSP scenarios, per IPCC WGII Continental
7 Region (see SMCCP5.1 and Tables SMCCP5.1-5.4).
8
9
10 CCP5.2 Observed Impacts and Adaptation in Mountain Social-Ecological Systems
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12 CCP5.2.1 Ecosystems and Ecosystem Services
13
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FINAL DRAFT Cross-Chapter Paper 5 IPCC WGII Sixth Assessment Report
1 Changes in climate over short distances in mountains are reflected in large ecological gradients. AR5
2 reported new evidence that plant species of mid and low elevations were starting to colonise high elevations
3 in mountains. Since AR5, new studies have been published (e.g. Steinbauer et al., 2018; Payne et al., 2020 ),
4 including in some previously less well studied areas such as the Andes (e.g. Morueta-Holme et al., 2015;
5 Báez et al., 2016) and parts of Asia (e.g. Telwala et al., 2013; Artemov, 2018). There is now high confidence
6 that many plant species distributions have shifted to higher elevations in recent decades, consistent with
7 climatic warming (Sections 2.4.2; 10.4.2.1.1; 13.3.1.1). In recent years publications have also started to show
8 similar trends in some animal species include those on birds (Freeman et al., 2018; Bani et al., 2019;
9 Lehikoinen et al., 2019) and snails (Baur and Baur, 2013). Other climatic variables besides temperature can
10 also affect elevational limits of species (Section 2.4.2) and sometimes in contrasting ways to temperature, for
11 example increasing precipitation can allow some species to occur at lower elevations in dry climates
12 (Crimmins et al., 2011; Coals et al., 2018). Tsai et al. (2015) reported large changes in the montane bird
13 community in Taiwan which they link to changes in weather patterns including more severe typhoons.
14 Changes in the amplitude and frequency of bank vole population waves in the Ilmen Nature Reserve, Middle
15 Urals can be linked to a longer frost-free periods (Kiseleva, 2020).
16
17 There are interactions with land use, for example a decrease in forest cover can exacerbate the effects of
18 rising temperatures (Guo et al., 2018). In contrast, Bhatta et al. (2018) showed a downward shift of species
19 assemblages in Langtang National Park, Nepal, most likely related to interactions with land use, especially
20 reduced grazing. Where glaciers are retreating, new areas become available for pioneer species to colonise
21 and new communities to form (Cuesta et al., 2019; Hock et al., 2019; Muhlfeld et al., 2020). The risk of
22 extreme events such as wildfire, drought, floods and landslips is increasing in a wide range of places as a
23 result of climate change and the evidence of the disturbance they cause to ecosystems has grown in recent
24 decades (Section 2.3.1, Box CCP5.1). The impacts of such extreme events may be larger than those of
25 incremental changes.
26
27 For species at lower elevations, mountains may represent refugia to which they can retreat. In this respect,
28 Elsen et al. (2018) have highlighted the importance of protecting areas along elevational gradients. This
29 applies in freshwater as well as terrestrial habitats with mountain streams acting as potential refugia (Isaak et
30 al., 2016). In contrast, species restricted to the highest elevations are increasingly at risk, including from
31 competition with colonising species (Britton et al., 2016; Winkler et al., 2016). Mountain top species are
32 often separated from potential new habitat by large areas with unsuitable climates and tropical mountain
33 species often have particularly narrow thermal tolerance and limited dispersal capacity (Polato et al., 2018).
34
35 The risks posed by non-native species may increase with climate change (Carboni et al., 2018; Shrestha et
36 al., 2018; Thapa et al., 2018). Koide et al. (2017) found that non-native plant species on Hawaii were moving
37 to higher elevations, whereas native species distributions were retracting at their lower elevational limit.
38 Dainese et al. (2017) found that non- native plant species spread to higher elevations approximately twice as
39 fast as native species. Following recent climate warming, invasive bamboo Phyllostachys edulis and
40 Phyllostachys bambusoides (Poaceae) in Japan has shifted northward and upslope in the last three decades
41 (Takano et al., 2017). New evidence has shown that variations in microclimate, with topography and cold
42 groundwater seeps, can provide micro-refugia small areas of locally suitable conditions where cold adapted
43 species can survive (Bramer et al., 2018; Muhlfeld et al., 2020) (Section 2.6.2). Some alpine species have
44 thrived in recent years, and the range of microclimates may partly explain this (Rumpf et al., 2018).
45
46 Treeline elevation is linked to temperature (Paulsen and Körner, 2014) but may also be affected by water
47 supply (Sigdel et al., 2018; Lu et al., 2021) and land management. A recent summary of treeline shifts
48 worldwide found that 67% of studied alpine treelines had shifted upwards while 33% remained stable (based
49 on 142 published studies); 88.8% of the 143 undisturbed alpine treelines across the northern Hemisphere had
50 shifted upwards (Hansson et al., 2021; Lu et al., 2021). Since AR5, new evidence of shifting treeline
51 ecotones has emerged for a wide variety of species in different locations including in Siberia (Pospelova et
52 al., 2017), various parts of the Ural Mountains (Shiyatov and Mazepa, 2015; Zolotareva and Zolotarev, 2017;
53 Sannikov et al., 2018), in Canadian Rocky Mountains (Trant et al., 2020) and Himalaya (Tiwari and Joshi,
54 2015; Chakraborty et al., 2016; Gaire, 2016; Yadava et al., 2017). Recent studies of treelines that have not or
55 hardly shifted include the Himalaya (Singh et al., 2015; Sigdel et al., 2018), eastern Tibetan Plateau (Wang
56 et al., 2020), and the Andes (Lutz et al., 2014). Migration rates are not proceeding as fast as warming
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1 climate, implying other processes also limit treeline ecotone response (e.g. Sigdel et al., 2020; Lu et al.,
2 2021).
3
4 Whether treeline shifts occur, and if so at what rate, depends on a range of factors including: land use
5 (especially livestock grazing and fire), species interactions, wildfires, and climatic stress factors (wind, frost,
6 drought, excess or shortage of snow) interacting with tree population processes (viable seed production,
7 dispersal, seedling establishment, clonal propagation, growth, dieback, mortality). Differences in treeline
8 shifts between North- and South-facing slopes have been demonstrated in the Rocky Mountains (Elliott and
9 Cowell, 2015). Grigorieva and Moiseev (2018) showed that significant factors limiting the number of
10 seedlings and shoots are the snow depth, the topsoil temperature dependent on it, and the degree of
11 competition from the parental tree stand and grassshrub vegetation. There is also an influence of land use
12 and management in many mountains around the world. Suwal et al. (2016) found that elevational shifts in
13 Himalayan silver fir in Nepal were larger when areas were protected from management. Similarly, Lutz et al.
14 (2014) found faster treeline shifts in the Peruvian Andes in protected areas than that in other areas, where
15 cattle grazing and fires are more frequent. Treeline ecotones can also change independent of climate change
16 if land use changes (Vitali et al., 2019; Körner, 2020).
17
18 Changes in community composition are also happening within ecosystem types. Duque et al. (2015) showed
19 a change in the composition of north Andean forests, and Feeley et al. (2013) in that of forests up to 2800 m
20 in Costa Rica. In both cases the proportion of species adapted to warmer conditions increased, driven
21 primarily by patterns of mortality, indicating that the changes in composition are mostly via range
22 retractions, rather than range shifts or expansions. An analysis of 200 forest inventory plots in the Andes
23 likewise indicated a widespread, though not ubiquitous, thermophilization of the tree species' composition
24 (Fadrique et al., 2018). Within a period of eight years (20032010), significant shifts in communities of
25 vascular plants, butterflies and birds were found in Switzerland (Roth et al., 2014). At lower elevations,
26 communities of all species groups changed towards warm-dwelling species, corresponding to an average
27 uphill shift of 8 m, 38 m and 42 m in plant, butterfly and bird communities, respectively. However, rates of
28 community changes decreased with elevation in plants and butterflies, while bird communities shifted
29 towards warm-dwelling species at all elevations (Roth et al., 2014).
30
31 Changes in mountain biodiversity and ecosystems have a wide range of impacts on ecosystem services and
32 effects on people. Some mountain ecosystems, particularly those with peatlands or forests are important
33 carbon stores and climate change presents a risk to these in some locations (Dwire et al., 2018) (Sections
34 2.4.3.8; 2.4.4.4; 2.4.4.5). Palomo (2017) identified a wide range of threats to the lives, livelihoods and
35 culture of mountain people as a consequence of the impacts of climate change on ecosystems. However,
36 impacts are very heterogeneous between locations, even within the same region and ecosystem type (for
37 example mountain forests in Europe; Mina et al. (2017) and are not necessarily all negative. As well as
38 changes in services, other impacts on humans from a changing climate may be mediated through species and
39 ecosystems, for example changes in vector distribution shifting disease incidence into higher elevation areas
40 (Escobar et al., 2016).
41
42
43 [START BOX CCP5.1 HERE]
44
45 Box CCP5.1: Wildfires and Mountain Ecosystems
46
47 Mountain ecosystems have long been known to be highly sensitive to the direct impacts of climatic warming
48 and drying (Beniston et al., 1994; Nogués-Bravo, 2009; Gottfried et al., 2012; Guisan et al., 2019).
49 Furthermore, wildfires in these ecosystems, as with many others (Sections 2.4.4.2 and 2.5.3.2), are also
50 expected to increase (Abatzoglou et al., 2019). This is because the occurrence and severity of fire is
51 governed by four fundamental processes that are intricately linked to climate: 1) fuel biomass growth; 2) fuel
52 moisture and type; 3) ignition source; and 4) favourable weather conditions for fire spread (Bradstock,
53 2010).
54
55 In temperate and tropical mountain ecosystems, increases in fire activity are potentially linked to changing
56 climate on most continents, including Europe (Dupire et al., 2017), North America (Westerling, 2016;
57 Halofsky et al., 2020; Burke et al., 2021), South America (Román-Cuesta et al., 2014), Africa (Hemp, 2005),
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1 Asia (Tian et al., 2014) and Australia (Bradstock et al., 2014; Abram et al., 2021). In these ecosystems, fire
2 frequency, severity and extent (i.e. the fire regime) are increasing because of climate-induced impacts on fuel
3 moisture (Gergel et al., 2017; Littell et al., 2018), vegetation composition (i.e. fuel types) (Camac et al.,
4 2017; Prichard et al., 2017; Zylstra, 2018), fire-conducive weather patterns and the length of fire seasons
5 (Westerling, 2016; Fill et al., 2019; Di Virgilio et al., 2020).
6
7 Fire in mountain ecosystems alters many ecological processes and ecosystem services across all elevational
8 zones, from foothill montane forests to the high elevation alpine (treeless) zones (Turner et al., 2003;
9 Williams et al., 2008; Oliveras et al., 2014; Rocca et al., 2014; Oliveras et al., 2018). However, the
10 magnitude of short-term and long-term fire impacts depends on the degree of novelty of future fire regimes
11 and the capacity of species to adapt to change (Camac et al., 2017; Archibald et al., 2018; Camac et al.,
12 2021).
13
14 Montane and subalpine ecosystems have variable ecological responses to fire that are ultimately influenced
15 by long-term, historical fire regimes and the evolutionary forces that have governed post-fire regeneration
16 strategies of the biota. Two contrasting strategies in temperate forests are illustrated here. SE Australian
17 mountain ash (Eucalyptus regnans) forests are adapted to a high severity fire regime, consisting of infrequent
18 (>100 years), large stand-replacing wildfires (Bowman et al., 2016). Mountain ash is a long-lived obligate
19 seeder but is slow to reach reproductive maturity (>20 years; Bowman et al., 2016). As such, natural post-
20 fire regeneration takes decades to centuries to recover to pre-fire conditions, and if fire recurs before
21 reproductive maturity is reached, the species can be eliminated. By contrast, ponderosa pine (Pinus
22 ponderosa) forests of the SW United States have evolved with a low- or mixed-severity fire regime, where
23 fire is frequent (5-25 year), low intensity, less likely to kill the dominant stand, and thus, allow faster post-
24 fire recovery (Prichard et al., 2017). However, post-fire recovery times in this ecosystem are also becoming
25 longer due to a century of effective fire suppression shifting the fire regime to one which is more infrequent,
26 high-intensity, extensive and stand replacing (Prichard et al., 2017).
27
28 Above the treeline, fire is less common than in foothill forests. Post-fire recovery times also tend to be
29 shorter (Williams et al., 2008; Camac et al., 2013; Verrall and Pickering, 2019) because of the dual
30 influences of the low flammability traits coupled with most alpine plant species exhibiting strong resprouting
31 strategies that have evolved in response to harsh climate conditions (Körner, 2003). However, fires in alpine
32 treeless landscapes can still have long-term and catastrophic impacts on fire-sensitive vegetation types such
33 as ground-water dependent wetlands dominated by hygrophilous plants and peat soils (De Roos et al., 2018).
34 Similar impacts can be severe on long-lived, slow growing vegetation such as coniferous heathlands
35 (Bowman et al., 2019), and highly restricted and threatened fauna (e.g. Mountain pygmy possum) that
36 depend on these plant communities (Gibson et al., 2018). Such fires have even been found to have
37 significantly impact subalpine treeline mortality rates (Fairman et al., 2017), and in some cases have resulted
38 in treelines shifting to lower elevations (e.g. Hemp, 2005).
39
40 The long-term implications of a warmer global climate, coupled with more frequent and/or severe fires in
41 mountain ecosystems, are expected to be transformative for mountain biota. Fire sensitive montane forests,
42 such as Australia's alpine ash (Eucalyptus delegatensis) are expected to become highly susceptible to
43 population collapse and local extinction as intervals between fire events contract and become too short for
44 species to reach reproductive maturity (Bowman et al., 2014; Enright et al., 2015) an impact that will likely
45 be further exacerbated by recruitment failure caused by post-fire drought and moisture deficiencies (Davies
46 et al., 2019; Halofsky et al., 2020; Rodman et al., 2020). Fire and climate change are also likely to act
47 synergistically in mountainous ecosystems, via positive feedbacks that increase fire frequency by changing
48 vegetation composition to more flammable fuel types, and thus increasing landscape susceptibility to future
49 fire (Camac et al., 2017; Tepley et al., 2018; Zylstra, 2018; Lucas and Harris, 2021). More frequent fires in
50 these ecosystems will also exacerbate native and exotic species invasions (Catford et al., 2009; McDougall et
51 al., 2011; Gottfried et al., 2012; Kueffer et al., 2013), faunal population declines (Ward et al., 2020), poor air
52 quality (de la Barrera et al., 2018; Burke et al., 2021), soil erosion and landslide risk (de la Barrera et al.,
53 2018), and reduce freshwater catchment volumes and quality (Rust et al., 2018; Niemeyer et al., 2020), all of
54 which will impact negatively on human health and wellbeing (Ebi et al., 2021).
55
56 Taking this evidence together, there is a significant risk of wildfire exacerbating other impacts of climate
57 change on already vulnerable ecosystems in many mountain regions (medium confidence).
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1
2 [END BOX CCP5.1 HERE]
3
4
5 CCP5.2.2 Water and Energy
6
7 CCP5.2.2.1 Water
8
9 Water is a fundamental source of life in mountain regions; it is also a central element and `connector' in
10 coupled natural-human systems and bears diverse meanings in different socio-cultural contexts, including in
11 indigenous ontologies (Boelens, 2014). Water is also a key component connecting upstream mountains and
12 downstream lowlands (Salzmann et al., 2016; Di Baldassarre et al., 2018; Encalada et al., 2019). Mountains
13 are of paramount importance as water towers for people in the mountains and for around 2 billion people
14 living in connected lowland areas (Immerzeel et al., 2020; Viviroli et al., 2020).
15
16 Mountain river systems are especially sensitive to, and affected by, climate change and continuing
17 anthropogenic disturbance, including water pollution, hydropower development, water withdrawals for
18 agriculture and human consumption, and biodiversity loss and ecosystem changes (Honda and Durigan,
19 2016; Encalada et al., 2019; Bissenbayeva et al., 2021; Chen et al., 2021) (high confidence). The effect of
20 climate and cryosphere change in mountains on downstream water and river systems has been studied and
21 quantified for many regions worldwide (Barnett et al., 2005; Huss, 2011; Lutz et al., 2014; O'Neel et al.,
22 2015; Huss and Hock, 2018). Comprehensive approaches focusing on both water demand and supply aspects
23 provide regionally or locally specified information on water availability, scarcity and security (Buytaert et
24 al., 2014; Drenkhan et al., 2015; Brunner et al., 2019) (Chapter 4). Present and potential future hotspot
25 regions of water scarcity that rely heavily on mountainous water sources include Central Asia, South Asia,
26 tropical and subtropical western South America, and southwestern North America (robust evidence, medium
27 agreement) (Kummu et al., 2016; Biemans et al., 2019; Immerzeel et al., 2020; Viviroli et al., 2020).
28
29 Figure CCP5.2 represents different levels of dependences of lowland areas on mountain water. At a global
30 scale, 68% of irrigated agricultural areas in lowlands depend on essential runoff contributions from the
31 mountains. The dependence of lowland populations on essential mountain runoff contributions increased by
32 a factor of more than three from the 1960s to the 2000s, with increases of up to ten-fold in some major river
33 catchments (Viviroli et al., 2020).
34
35 Many mountain regions have one or more cryosphere components (glaciers, permafrost and perennial or
36 seasonal snow), and the mountain cryosphere is among the natural systems most sensitive to climate change
37 worldwide (high confidence). The SROCC assessed a decline in all cryosphere components due to climate
38 change over the past decades, i.e. for low-elevation snow cover (high confidence), permafrost (high
39 confidence), and glaciers (very high confidence) (Hock et al., 2019). More recent studies using globally more
40 complete data sets show a considerably higher glacier mass loss (267 ±16 Gt yr-1) for 2000-2019 as
41 compared to a (very likely2) range of 123 ±24 Gt yr-1 for 2006-2015 in SROCC, with a mass loss acceleration
42 of 48 ±16 Gt per year and decade over 2000-2019 (Hugonnet et al., 2021). Assessment conclusions in
43 SROCC found with high confidence that glacier shrinkage and snow cover changes over the past two
44 decades has led to changes in the amount and timing of runoff in many mountain regions (Hock et al., 2019).
45
46 The effects of climate and environmental changes in upstream areas on downstream water quantity and
47 quality, including nutrient, pollutant, heavy metals and sediment flux, have only been assessed in a limited
48 number of catchments (Rakhmatullaev et al., 2009; Dong et al., 2015; Milner et al., 2017; Ilyashuk et al.,
49 2018; Lane et al., 2019; Li et al., 2020; Chen et al., 2021). Groundwater contributions to streamflow are
50 highly variable in mountains, but can be substantial (up to 70 to 80% or more) during low-flow periods
51 (Frisbee et al., 2011; Baraer et al., 2015; Gordon et al., 2015; Käser and Hunkeler, 2016; Somers et al.,
2 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: 95
100%, 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 2019). Groundwater may provide some resilience to loss of melt water from glacier and snow decline but in
2 the longer term groundwater recharge and contribution to streamflow is expected to decrease with ongoing
3 climate change (medium confidence) (Somers and McKenzie, 2020). In some mountain regions springs are a
4 particularly important source of water, e.g. in the Himalayan region where large populations depend on
5 them. Observations indicate reduction of water provision from springs in recent years in the Himalaya,
6 caused by multiple causal factors (human interventions, climatic) (section 10.4.4.).
7
8 Both small-scale interventions (e.g. livestock grazing in sensitive high-elevation wetlands) as well as high-
9 investment interventions (e.g. hydropower dams and plants) in upstream regions can strongly affect water
10 availability, river connectivity, biodiversity and catchment management (Anderson et al., 2018; Ramsar
11 Convention on Wetlands, 2018; Encalada et al., 2019), and are often contested and have led to conflict
12 (medium evidence, high agreement) (Drenkhan et al., 2015; French et al., 2015). Climate change often
13 exacerbates tensions or conflicts between different users over water at local, national and transboundary or
14 regional scales; many tensions and social or political conflicts are documented, especially in seasonally dry
15 regions; where large power inequalities among users exists; where clear and established regulations are
16 lacking; and especially also in transboundary settings (e.g. Central Asia, Hindu-Kush-Himalaya, Andes)
17 (Carey et al., 2014; Bocchiola et al., 2017; Yapiyev et al., 2017; Hock et al., 2019; Mukherji et al., 2019).
18
19 Water plays a fundamental role in climate change adaptation in mountains. A majority of documented
20 adaptation efforts in mountain regions address water-related aspects (precipitation variability and extremes,
21 including drought, water availability, floods) (McDowell et al., 2019; McDowell et al., 2020) (high
22 confidence). This is a robust finding across different mountain regions and adaptation project and program
23 types, and also in line with findings for cryosphere change related adaptation as reported in SROCC (Hock et
24 al., 2019). Water also plays a role for adaptation in other sectors such as agriculture, disaster management
25 and tourism and recreation (McDowell et al., 2019). There is high confidence that water conservation efforts,
26 also including restoration and protection of particularly vulnerable areas (e.g., wetlands), and increase of
27 efficiency in water use, are robust, low-regret adaptation measures.
28
29
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1
2 Figure CCP5.2: Dependence of land surface areas and population on mountain water resources 19612050. Results are
3 shown as decadal averages for lowland population in each category of dependence on mountain water from no surplus
4 and negligible to essential; a) map of global mountain regions and their differentiated importance for lowland water
5 resources; b) map of lowland population and their differentiated dependence on mountain water resources, both for the
6 scenario combination SSP2-RCP6.0 and for the time period 2041-2050; c) number of lowland population and their
7 differentiated dependence on mountain water resources from the 1960's to the 2040's for three different scenario
8 combinations (based on Viviroli et al., 2020).
9
10
11 CCP5.2.2.2 Energy
12
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1 Increasing temperatures and variability in precipitation and river flow affect energy availability and use in
2 mountain regions. Mountain peoples, more so than national or global populations, are dependent on local
3 sources of energy, accentuating climate adaptation cost and barriers (medium evidence, high agreement)
4 while also offering opportunities for mountain-specific solutions (medium evidence, high agreement). In
5 mountain regions, inadequate infrastructure (Tiwari et al., 2018), remoteness, and reliance on traditional
6 forms of energy that may be difficult to diversify (Dhakal et al., 2019), exacerbating impacts of climate
7 change on energy use and demand.
8
9 A review of the renewable energy transition in the context of adaptation across global mountain regions,
10 including hydropower, wind, solar and biomass, shows that observed climate change impacts on these
11 energy sources include altered seasonality, timing as related to snow and glacial melt runoff (30.9% of
12 analysed cases), variable or declining precipitation and runoff (26.4%), increased flooding (15.5%), altered
13 wind patterns (8.2%), and other/not specified effects (19.1%) (Scott et al., 2019). Combined effects of
14 climate change, hydropower development and further anthropogenic effects in upstream mountain basins,
15 have increased and are expected to further negatively affect several aspects of ecosystem functions and water
16 security (e.g. negative effects on river geometry, water chemistry, sediment transport, fish composition and
17 migration) (Anderson et al., 2018; Encalada et al., 2019; Lepcha et al., 2021) (high confidence).
18
19 With respect to hydropower, mountains have a unique role for the production of renewable energy for large
20 downstream populations, but it also comes with important trade-offs affecting mountain ecosystems and
21 populations (high confidence) (Farinotti et al., 2019; Viviroli et al., 2020; Vaidya et al., 2021). Climate
22 change requires adaptation in the hydropower sector; for instance, some advocate for increased water storage
23 in dams and the importance of mountains for pumped hydropower storage systems (Gurung et al., 2016;
24 Hunt et al., 2020), while others emphasize adaptive water management (Gaudard et al., 2014; Caruso et al.,
25 2017b). An example is multi-purpose use of water strategies where water management storage is designed to
26 accommodate different uses, including hydropower, agriculture, and flood risk reduction (Haeberli et al.,
27 2016a; Drenkhan et al., 2019) (Section 12.6.3). Hydropower is also particularly exposed to glacier and snow
28 decline (Schaefli et al., 2019), and is subject to risks from extreme events (Rangecroft et al., 2013;
29 Schwanghart et al., 2016; Mishra et al., 2020; Shugar et al., 2021), social and political opposition (Ahlers et
30 al., 2015; Díaz et al., 2017) and the resulting financial uncertainty for hydropower investors. There is still
31 limited evidence on how climate change impacts wind, solar and biomass energy production, and use.
32
33 Overall, synergies between adaptation to climate change and renewable energy transition can be successfully
34 generated where benefit-sharing improves local involvement and support, adaptive capacity is enhanced,
35 local health and livelihoods supported, Sustainable Development Goals (SDGs) met, and environmental
36 justice considered and sustainable mountain development pursued (high agreement, medium evidence).
37
38 CCP5.2.3 Food, Fibre, and Other Mountain Ecosystem Products
39
40 There is high confidence that climate change is largely negatively impacting on food, fibre and other
41 ecosystem products, including agriculture (Porter et al., 2014; Ingxay et al., 2015; Upgupta et al., 2015;
42 Chirwa et al., 2017; Rojas-Downing et al., 2017; Chitale et al., 2018; Pretzsch et al., 2018; Barberán et al.,
43 2019; Sultan et al., 2019; Huang and Hao, 2020; Godde et al., 2021), and ecosystem services (Gręt-Regamey
44 and Weibel, 2020) across many different mountainous region e.g. Africa (Bondé et al., 2019; Musakwa et
45 al., 2020), Asia (Guo et al., 2018; Sunderland and Vasquez, 2020), Europe (Nair, 2019), North America
46 (Hupp et al., 2015; Prevéy et al., 2020), South America (Herman-Mercer et al., 2020) (Section 5.4, 5.4.1,
47 5.5.1, 5.6.2, 5.7, 5.11.1.1).
48
49 Ecosystem products are vital to support the livelihoods and economic prospects for communities living in
50 and around mountains (Figure CCP5.3). For instance, collection and trade of caterpillar fungus contributed
51 to 53.3 - 64.5% annual household cash income in Nepal (Shrestha and Bawa, 2014; Shrestha et al., 2019);
52 40-80% in Bhutan (Thapa et al., 2018); 60-78% in Uttarakhand, India (Laha et al., 2018; Yadav et al., 2019)
53 (Section 5.7.1). Livelihood support from ecosystem products in Southern Malawi region (Pullanikkatil et al.,
54 2020), south-western Ethiopian mountains (Nischalke et al., 2017) and Southern China (Min et al., 2017),
55 Himalayan mountains (Nepal et al., 2018), South Africa (Ngwenya et al., 2019) is reported. Additionally, the
56 sacredness of mountains in different religions and cultures is widely acknowledged (Ceruti, 2019; Benedetti
57 et al., 2021).
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1
2 Climate change and associated impacts on multiple ecosystem services and related products (timber
3 production, carbon sequestration, biodiversity and protection against natural hazards) have been observed
4 across European mountains, e.g. in central Iberian Mountains (Spain), Western and Eastern Alps (France,
5 Austria) and Dinaric Mountains (Slovenia) (Mina et al., 2017). Dumont et al. (2015) demonstrated that
6 climate change negatively affects the forage nitrogen (N) content by 8% but increase the total non-structural
7 carbohydrate content by 25% in European mountains. Positive impacts have been reported on mushroom
8 productivity in the mountains of Spain (Karavani et al., 2018) (Section 5.7.3.3), yet negative impacts on the
9 Ophiocordyceps in the Himalayan region (Hopping et al., 2018), likewise on apple production in Himachal
10 Pradesh, India, which declined by 9.4 tonnes per hectare in the past two decades (Das, 2021). Shifts in crop
11 wild relatives richness from south to north, and increase in the numbers of threatened taxa with an increase
12 of 1.5 and 30C temperature rise, have been observed in European mountains (Phillips et al., 2017).
13
14 Medicinal and aromatic plants and their secondary metabolites are also observed to be affected by climate
15 change (Das et al., 2016; Zhang et al., 2019a) (medium confidence). Phenological changes like early
16 flowering and reduced vegetative phase are negatively affecting the productivity of such plants (Harish et al.,
17 2012; Gaira et al., 2014; Maikhuri et al., 2018). While increasing atmospheric temperature and CO2 are
18 reported to improve the biomass of Gynostemmapentaphyllum (Chang et al., 2016) (Section 5.7.3.3), they
19 adversely affect its antioxidant compounds/activity, health-promoting properties and phytochemical content
20 (Gairola et al., 2010; Das et al., 2016; Kumar et al., 2020). Experimental trials have shown that when
21 medicinal plants are stressed by drought there is an increase in phytochemical content, either by decreasing
22 biomass or by increasing actual production of the metabolites (Selmar and Kleinwächter, 2013; Al-Gabbiesh
23 et al., 2015) (medium confidence). Strong effects of climatic and non-climatic factors have been observed to
24 affect the distribution of selected medicinal plants species in northern Thailand (Tangjitman et al., 2015), as
25 well as in Egypt, Sub-Saharan Africa, Spain, Central Himalaya, China, Nepal, with some species at risk of
26 being lost (Munt et al., 2016; Yan et al., 2017; Brunette et al., 2018; Chitale et al., 2018; Zhao et al., 2018;
27 Applequist et al., 2020). Negative climate-related impacts on the distribution range of forty one medicinal
28 plant species have been predicted for Spanish and Asian mountains (Munt et al., 2016) (Section5.7.3.3), and
29 decreasing size of fruits of Myrica esculenta in Himalaya (Shah and Tewari, 2016).
30
31
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1
2 Figure CCP5.3: Impact of climate change on mountain social-ecological systems, including ecosystem services and
3 products, livelihoods of mountain people and examples of adaptation options to address direct and indirect impacts.
4
5
6 CCP5.2.4 Cities, Settlements and Key Infrastructure
7
8 Mountain settlements and people are globally distributed and represent a significant proportion of the total
9 global population that is exposed to the effects of climate change (Section CCP5.1, SMCCP5.1). Cities with
10 one or several million inhabitants located in mountainous environments or at high elevations are
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1 predominantly found in Latin America e.g., in El Alto and La Paz (Bolivia), Quito (Ecuador), Mexico City
2 (Mexico) and Bogotá (Colombia); Asia e.g., Kabul (Afghanistan), Kathmandu (Nepal), Srinagar (India),
3 Peshawar (Pakistan), Quetta (Pakistan), Xining and Kunming (China), and Dehradun (India); and in Africa
4 e.g., Harare (Zimbabwe) and Addis Ababa (Ethiopia) (Wang and Lu, 2018; Balderas Torres et al., 2021;
5 Ehrlich et al., 2021). Mountain regions also host many settlements with fewer than 500,000 inhabitants
6 (Alfthan et al., 2016). In many cases, particularly in developing countries, portions of the population also
7 reside in informal and low-income settlements (French et al., 2021), where rates of poverty and inequality
8 exacerbate their vulnerability and exposure to climate-related hazards such as landslides (Alfthan et al. 2018)
9 (Section CCP5.2.5.1), environmental pollution or even pandemic diseases (Marazziti et al., 2021).
10
11 In many mountain regions, particularly in developing countries, the increasing urban population has put
12 considerable pressure on water services and basic amenities for urban dwellers (Singh et al., 2021), for
13 example in cities such as La Paz (Kinouchi et al., 2019), which are regions already under pressure due to the
14 negative effects of climate change coupled with poor water availability and governance (Chapter 4; Section
15 CCP5.2.2.1; FAQ CCP5.1; Hock et al. (2019). In many areas of the Hindu Kush Himalaya (HKH) region,
16 water demand far exceeds municipal supply and people often cope with water insecurity in myriad ways
17 (Bharti et al., 2020; Sharma et al., 2020; Singh et al., 2020), such as turning to inter-basin water transfers and
18 deep pumping to supply their water needs (Ojha et al., 2020). Additionally, the influx of migrants, tourists
19 and retirees, combined with the growth of the incumbent population, places considerable stress on urban
20 infrastructure to supply adequate clean water and sewage disposal (Prakash and Molden, 2020), which is also
21 observable in other regions (Chapter 4; Section 6.4.7; Case Study 6.1 in Chapter 6). Energy provision in and
22 around mountain settlements, is another key sector affected by climate-related impacts (Hock et al., 2019)
23 (CCP5.2.2.2), and which bear relevance for the adaptation prospects for urban mountain settlements
24 (medium confidence).
25
26 CCP5.2.5 Mountain Communities, Livelihoods, Health and Wellbeing
27
28 People living in and around mountain regions strongly depend on the ecosystem functions, services and
29 resources available in these areas for their livelihoods, health and wellbeing. Overall, subsistence agriculture
30 and livestock remain key sources of livelihood in many mountain regions (FAO, 2019), with non-agricultural
31 income sources such as remittances, small businesses, medicinal plants, wage labour and tourism also
32 contributing to these economies (Montanari and Koutsoyiannis, 2014; Palomo, 2017; Minta et al., 2018).
33 This section provides an illustrative overview of key reported observed impacts and adaptation responses to
34 climate change on mountain communities (Table CCP5.1), and livelihood activities and economic sectors
35 such as agriculture and pastoralism, and tourism and recreation (Table CCP5.2), reported since AR5.
36
37
38 Table CCP5.1: Overview of key observed impacts and adaptation on mountain communities livelihoods and poverty;
39 migration, habitability, and displacement; health and wellbeing.
Overview of key observed impacts and adaptation on mountain communities References and relevant
AR6 WGII Sections
Mountain livelihoods and poverty
Impacts · In some mountain regions, the incidence of poverty can be higher Gioli et al. (2019); Tiwari
compared to other areas, with observed impacts of climate change and Joshi (2012); Rasul
Responses · intensifying the deterioration of socio-economic conditions that
and support livelihoods, thereby exacerbating already existing conditions and Hussain (2015);
of non-climate related vulnerabilities and livelihood insecurity Hussain et al. (2019);
adaptation (medium confidence). McDowell and Hess
(2012); FAO (2015); FAO
(2019); Shrestha et al.
(2015); Motschmann et al.
(2020a); Section 8.3
Diversification of livelihoods through the integration of drought- Ashraf et al. (2014); Hussain
resilient livestock and crops and changes in farming practices (i.e. et al. (2016a); Skarbř and
water management or migration of crops from low to high land) with
some shifting to non-agricultural livelihood options, reported for VanderMolen (2016); Nkuba
cases such as in the HKH, the Andes, Rwenzori mountains of et al. (2020); Yohannes et al.
Uganda and Simien Mountains of Ethiopia.
(2020); CCP5.4.1
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Overview of key observed impacts and adaptation on mountain communities References and relevant
AR6 WGII Sections
Migration, habitability and displacement
Impacts · There is growing evidence of links between climate change impacts Wrathall et al. (2014); Hunter
· and migration and mobility through a complex web of causal links et al. (2015); Brandt et al.
· (medium confidence). In mountain contexts, migration and mobility (2016); Mastrorillo et al.
·
are indirectly impacted by climate change through adverse effects on (2016); Gautam (2017);
Responses ·
and mountain livelihoods that are dependent on mountain ecosystem Sagynbekova (2017); Cattaneo
adaptations services. et al. (2019); Maharjan et al.
·
(2020)
Extreme events are resulting in temporary and in some cases Iribarren Anacona et al.
permanent displacement of populations in mountains (medium (2015); Stäubli et al. (2018);
confidence), with hazards such as floods and mass movement IDMC (2020); Wang et al.
(avalanche, flood, landslide) leading to population displacements
e.g., in Afghanistan, Pakistan, Peru, Thailand, and Uganda. (2020)
Cases of entire settlements either abandoned or relocated due to Mueller et al. (2014);
prolonged slow onset events such as water shortage, drought, and Nawrotzki and DeWaard
heat stress have been reported. (2016); Prasain (2018)
In contrast, place attachment is increasingly cited as one of the Adams (2016); Dandy et al.
reasons for the immobility choices for some people. However, in (2019); Khanian et al. (2019);
some cases, vulnerability to climatic events contribute to the in-
migration decisions of vulnerable populations exposed to hazards Islam et al. (2020)
from downstream to upland areas.
Migration, in turn, is often cited as a risk management strategy, Banerjee et al. (2018);
where migration can lead to the diversification of livelihood options, Banerjee et al. (2019);
improves access to information and resources, and expands social Siddiqui et al. (2019);
networks, all of which can support households in their capacity to Maharjan et al. (2020);
adapt to climate change impacts Maharjan et al. (2021)
Migration is often gendered, with men migrating and leaving women
to manage households at origin. Women's capacities are often
constrained due to institutional barriers and social norms, resulting
in low adaptive capacity and increased vulnerability to hazards.
Capacity-building interventions strengthens adaptation capacity as
well as links to access institutional support (medium confidence).
Health and wellbeing
Impacts · Direct links between climate change and health in mountain regions Dantés et al. (2014); Siraj et
are reported in terms of physical injury or fatality due to exposure to al. (2014); Dhimal et al.
climate-related hazards such as floods or landslides, or exposure to (2015); Wu et al. (2016);
vector-borne diseases such as malaria or dengue fever reported at Equihua et al. (2017); Alfthan
higher elevations with warming temperatures (medium confidence), et al. (2018); Gilgel et al.
such as in Mexico, Nepal, Ethiopia, and Colombia. (2019); Chapter 7
· Indirect impacts to health by climate change are linked to water- Table 7.6
borne diseases and pathogens associated with floods and droughts.
· Whilst reports on the ongoing challenges associated with the Baiker et al. (2020); Cross-
COVID-19 pandemic are emerging in relation to their compounding Chapter Box COVID in
impacts on adaptive capacities, there is limited evidence to assess Chapter 7
those effects with respect to other climate-related impacts on health.
· Mental health issues associated with climate-related impacts are Trombley et al. (2017);
reported with respect to climate anxiety and ecological grief and Cunsolo and Ellis (2018);
their effects on the wellbeing of individuals. For example, the grief Clayton (2020); Sideris (2020)
and loss associated with changes in glaciated landscapes, such as the
`death' of the Okjökull glacier in Iceland. However, there is limited
evidence on mountain-specific cases and experiences that would
allow for an assessment of the broader and longer-term impacts to
mental health associated with a changing climate in the mountains.
· Other heightened vulnerability to climate-related impacts on health Furberg et al. (2011); Section
and wellbeing are also experienced by specific groups, for example 7.1.7.2
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Overview of key observed impacts and adaptation on mountain communities References and relevant
AR6 WGII Sections
Sami pastoralists facing changes in mountain snow cover that
negatively affect their reindeer herding, a key activity for their
identity and spiritual health.
Responses · Approximately a fifth of observed adaptations reported in the GAMI Furu and Van (2013); Section
and
mountain re-analysis address health and wellbeing as an aspect of CCP5.4.1
adaptations
vulnerability. This includes raising communities' awareness of and
coping strategies climate change-induced health issues.
1
2
3 Table CCP5.2: Overview of key observed impacts and adaptation on select livelihood activities and economic sectors
4 mountain agriculture and pastoralism; and tourism and recreation.
Overview of key observed impacts and adaptation on select livelihood activities References and relevant AR6
and economic sectors WGII Sections
Mountain Agriculture and Pastoralism
Impacts · Changes in temperature and seasonal precipitation patterns are Rangecroft et al. (2013);
affecting the timing and availability of water for agricultural Kaboosi and Kordjazi (2017);
activities (high confidence), e.g. in the Bolivian Andes, Andean- Hussain et al. (2018); Kalbali et
Amazon foothills of Colombia, Ecuador, and Peru, High Atlas of al. (2019); Zkhiri et al. (2019);
Morocco, the Hindu Kush Himalaya (HKH), and Golestan province Beltrán-Tolosa et al. (2020);
of Iran. Torres-Batlló and Martí-
Cardona (2020)
· Changes in temperature and seasonal precipitation patterns are Oliver-Smith (2014); Hussain et
reported to affect nutrient depletion of soils and increased incidence al. (2016b)
of pest attacks in crops, e.g. in cases in the HKH and in Peru,
however there is generally limited evidence on directs links to
climate-related changes in mountain regions, specifically.
· Climate-induced hazards such as erratic precipitation (rain, snow Hussain et al. (2016b);
and hail), floods, droughts and landslides have negatively affected Gonzales-Valero (2018); Thapa
the stable supply and transport of agricultural products in and out of and Hussain (2020)
remote mountain areas, such as in the Peruvian Altiplano and HKH.
· Warming temperatures and changes in timing of seasons and frost Buerkert et al. (2020)
conditions needed for seeding of certain tree crops, are impacting
lower elevation mountain areas, such as in Oman.
· Drought conditions are negatively affecting mountain grasslands Ashraf et al. (2014); Zomer et
(medium confidence), as reported in cases in Tyrol (Austria), Nepal, al. (2014b); Grüneis et al.
Afghanistan, Pakistan and China, which can contribute to a decline (2018); Adhikari et al. (2019);
in agrobiodiversity. Chaudhary et al. (2020);
Hussain and Qamar (2020)
· In some cases, climate-related hazards are leading to outmigration in Warner and Afifi (2014);
mountain areas, with indirect negative impacts on labour deficits to Wester et al. (2019)
support agricultural practices and productivity in mountain areas
(medium confidence), e.g. in Ghana, Tanzania, Thailand and HKH.
· Positive impacts (favourable growing conditions) are reported for Hussain et al. (2016b); Thapa
the production of some fruits and vegetables in Gilgit-Baltistan and Hussain (2020)
province of Pakistan, and for the production of traditional crops (e.g.
local beans) in the Karnali region of Nepal.
· Impacts on pastoralism include changes in growing conditions Batima et al. (2013); Rasul et al.
associated with warming temperatures and declining precipitation, (2014); Gentle and Thwaites
which in turn leads to negative impacts on livestock productivity, (2016); Kimaro et al. (2018);
food security and livelihoods of pastoralist communities, including Mekuyie et al. (2018); Tiwari et
drought-induced degradation of rangelands (medium confidence) al. (2020)
e.g. in mountainous areas of Mongolia, Tanzania, Nepal, and
Ethiopia, which exacerbate impoverished conditions for pastoral
communities.
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Overview of key observed impacts and adaptation on select livelihood activities References and relevant AR6
and economic sectors WGII Sections
Responses · Recharging groundwater and adopting rainwater harvesting Sections 4.7.1.1; 5.6.3; Cross-
and (including appropriate tillage methods to improve soil moisture), Chapter Box FEASIB in
restoration and rehabilitation of land, diversification of agricultural Chapter 18
adaptations crops (including introduction of stress resistant crop varieties),
promotion of in situ (protected areas, conservation areas) and ex situ
(nurseries, gene banks, home gardens) conservation strategies,
afforestation and agro-forestry.
· Local knowledge is being used to help maintain the productive and Fassio et al. (2014); Kmoch et
cultural value of mountain agriculture and pastoralism, such as in al. (2018); Das (2021)
the French and Italian Alps, Western Himalaya in India, and
mountains in northern Morocco.
· Ecosystem-based and community-based adaptation are contributing Reid (2016); Gręt-Regamey and
to supporting the diversity and complementarily of management Weibel (2020); Cross-Chapter
options, permaculture, and local capacities to adapt and support Box NATURAL in Chapter 2
ecosystem functions vital for agrobiodiversity (medium confidence).
Tourism and Recreation
Impacts · Since SROCC, the literature on climate change impacts on ski Hock et al. (2019); Sauri and
winter tourism has remained dominated by studies focused on future Llurdés (2020); AR6 WG1
· climate change impacts and projected risks due to decreasing Sections 9.5.3 and 12.4.10.4
· seasonal snow reliability (see CCP5.3.1), most relevant when
considering snow management and in particular snowmaking.
Responses ·
and Climate-induced hazards in mountains, such as rockfalls, are Hock et al. (2019); Mourey et
negatively affecting access to some climbing, mountaineering, and al. (2019); Mourey et al. (2020)
adaptation hiking routes in summer (medium confidence), with cases mainly
· reported in the European Alps.
· Higher temperatures and extreme heatwave conditions at lower Serquet and Rebetez (2011);
elevations have made some mountain destinations more appealing March et al. (2014); Pröbstl-
· for human comfort, increasing the potential summer visitation Haider et al. (2015); Steiger et
· demand and opportunities for tourism and recreation in mountains,
such as in the European Alps and the Catalan Pyrenees (medium al. (2016); Juschten et al.
confidence). However, there is limited evidence reported for similar (2019a); Juschten et al. (2019b)
trends in mountain regions outside of Europe.
Diversification of tourism activities to non-snow activities is Morrison and Pickering (2013);
reported as an adaptation approach to maintain economic viability in Sauri and Llurdés (2020)
some winter ski areas, partly due to the high cost of running
snowmaking infrastructure in winter e.g. in the Pyrenees (Europe)
and Australian Alps.
In some cases, managing the availability and demand for water Demiroglu et al. (2019);
resources used for snowmaking is reported, with destination and Gerbaux et al. (2020)
large-scale governance highlighted as critical aspects for managing
trade-offs, including overcoming conflicts arising from competing
demands for environmental resources and land use, e.g. in the
French Alps and in Scandinavia.
For snow management, there are examples of dedicated climate Köberl et al. (2021); Morin et al.
services designed to enable better-informed decision making on (2021)
appropriate long-term adaptation e.g. through a dedicated
Copernicus Climate Change Service, or real-time early warning
systems.
Barriers to adaptation strategies such as snowmaking, for instance in Matasci et al. (2014); Moser and
Switzerland, have been linked to perceived economic constrains to Baulcomb (2020)
their implementation, as well as the social acceptability of these
measures.
Adaptation options to limit exposure to hazards in hiking, climbing Hock et al. (2019); Mourey et
or mountaineering activities, include shifting the seasonal timing for al. (2019); Mourey et al. (2020)
practicing these activities, or changing routes entirely.
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Overview of key observed impacts and adaptation on select livelihood activities References and relevant AR6
and economic sectors WGII Sections
· In some cases, such as in Bolivia, Peru, and New Zealand, and more Hock et al. (2019); Salim and
recently reported in the French Alps, `last chance' tourism has Ravanel (2020)
increased the appeal of some mountain destinations, resulting in
visitation demand to witness the effects of climate change on iconic
mountain landscape features such as glaciers.
1
2
3 Other sections in this CCP provide detailed assessments that synthesise impacts and adaptation on the
4 detection and attribute of impacts to anthropogenic climate change (CCP5.2.7), projected impacts and key
5 risks (CCP5.3), and adaptation responses to reduce those key risks (CCP5.4.1).
6
7 CCP5.2.6 Natural Hazards and Disasters
8
9 Climate and weather-related disasters in mountain regions have increased over the last three decades
10 (medium confidence). Disaster frequency shows increasing trends in the Hindu Kush Himalaya, the Andes
11 and mountain regions in Africa, whereas no clear trends for the European Alps and Central Asia are
12 observed (medium confidence) (Froude and Petley, 2018; Stäubli et al., 2018).
13
14 Floods, debris flows, landslides and avalanches are the most frequent hazards affecting the highest number
15 of people in mountain regions (medium confidence) (Stäubli et al., 2018). Landslides count amongst the
16 deadliest hazards globally with over 150,000 reported fatalities for the period 1995-2014 (Haque et al.,
17 2019). There is high confidence that the number of fatalities from landslides has increased globally over the
18 past twenty years (Froude and Petley, 2018; Haque et al., 2019), but there is limited evidence that this is due
19 to changes in landslide event frequency and/or magnitude. Infrastructure expansion on unstable terrain can
20 increase disaster risk (Zimmermann and Keiler, 2015; Huggel et al., 2019; Kirschbaum et al., 2019;
21 Schauwecker et al., 2019; Terzi et al., 2019; Motschmann et al., 2020a; Shugar et al., 2021). A study from
22 western Nepal concludes that the exposure of people and infrastructure has been the main cause of disasters
23 (Muńoz-Torrero Manchado et al., 2021). Decreasing numbers of fatalities from disasters resulting from
24 decreasing vulnerabilities have been reported in Europe and North America (see Section 13.2.2.1) (Gariano
25 and Guzzetti, 2016; Strouth and McDougall, 2021). Evidence from Africa suggests that disasters from
26 climate induced natural hazards in mountain areas are often due to droughts, pests and changes to rainfall
27 and associated impacts on smallholder farmers' agricultural livelihoods (Shikuku et al., 2017).
28
29 Characteristics of natural hazards in mountain areas have been largely explored and evidence suggests that
30 conditions favouring cascading impacts are a common feature (high confidence) (Section 8.2.1.1)
31 (Zimmermann and Keiler, 2015; Huggel et al., 2019; Kirschbaum et al., 2019; Schauwecker et al., 2019;
32 Terzi et al., 2019; Motschmann et al., 2020a; Shugar et al., 2021). Compound and cascading impacts have
33 affected people, ecosystems and infrastructure and generate significant spillovers across numerous sectors,
34 resulting in destructive impacts (Nones and Pescaroli, 2016; Kirschbaum et al., 2019; Schauwecker et al.,
35 2019).
36
37 Most adaptation responses to natural hazards in mountain regions are reactive and autonomous to specific
38 climate stimuli or post-disaster recovery (robust evidence, medium agreement) (McDowell et al., 2019;
39 Rasul et al., 2020). Hard structural measures such as dikes, dam reservoirs and embankments have largely
40 been employed to contain the hazards alongside early warning systems, zonation and land management
41 (Sections 4.4.1.3, 10.3, 12.5.3, 13.2.2). Awareness raising, preparedness and disaster response plans are
42 increasingly used in the context of more unpredictable hazard trends (see Cross-Chapter Box DEEP in
43 Chapter 17) (Allen et al., 2016; Allen et al., 2018; Hovelsrud et al., 2018). Ecosystem based adaptations
44 (EbA) are widely implemented to mitigate risks from shallow landslides (e.g. afforestation and. reforestation
45 and improved forest management), floods (e.g. river restoration and renaturation) (Renaud et al., 2016; Klein
46 et al., 2019b) and droughts (e.g. adapting watershed) (Renaud et al., 2016; Klein et al., 2019b; Palomo et al.,
47 2021).
48
49 Evidence from different mountain regions show that adaptation and risk reduction efforts are less successful
50 if they focus on hazards or risks, without considering diverse risk and value perceptions of affected people
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1 (medium confidence) (French et al., 2015; Allen et al., 2018; Hovelsrud et al., 2018; Kadetz and Mock, 2018;
2 Klein et al., 2019b). Previous experience and local social contexts of exposure to climate-related disasters
3 affect the perception of people and influence the patterns associated with disaster risk management and
4 associated coping strategies (high confidence) (see SROCC Chapter 2) (Kaul and Thornton, 2014; Shijin and
5 Dahe, 2015; Landeros-Mugica et al., 2016; Wirz et al., 2016; Carey et al., 2017; Adler et al., 2019).
6
7 Important synergies exist between disaster risk reduction, climate change adaptation and sustainable
8 development in mountain regions (medium confidence) (Zimmermann and Keiler, 2015), where the multiple
9 and diverse perceptions of risk and risk tolerance to natural hazards are relevant considerations
10 (Schneiderbauer et al., 2021). Global agreements for integrated disaster risk management and climate change
11 adaptation (Alcántara-Ayala et al., 2017), including the Sendai Framework for Disaster Risk Reduction
12 20152030 (UNISDR, 2015), the SDGs (UN, 2015), the Paris Agreement (UNFCCC, 2015) and the New
13 Urban Agenda-Habitat III (UN, 2016) create opportunities for synergies to address disaster risks (see also
14 Section 6.3). Although these agreements are well established in the international agendas, there is limited
15 evidence of their implementation to address disaster risk reduction and adaptation in mountains (Alcántara-
16 Ayala et al., 2017).
17
18 CCP5.2.7 Synthesis of Observed Impacts and Attribution and Observed Adaptation
19
20 CCP5.2.7.1 Observed Impacts and Attribution to Anthropogenic Climate Change
21
22 The assessment of observed impacts identified a large number of impacts across all major mountain regions
23 of the world and for a large variety of systems, based on more than 300 references (see SMCCP5.2). The
24 literature was assessed, and results classified on a per regions and systems basis. Confidence statements on
25 detection and attribution are based on expert judgement following IPCC guidelines (see Section 1.3.4),
26 building on evidence from multiple sources in the literature (Mach et al., 2017) (see SMCCP5.2). Figure
27 CCP5.4 provides an overview of the assessment results.
28
29 Climate change impacts have been documented in mountains of all continents. A wide range of human and
30 natural systems have been affected by climate change to date, including the cryosphere, water resources,
31 terrestrial and aquatic ecosystems, agriculture, tourism, energy production, infrastructure, health and life,
32 migration, disasters and community and cultural values. The confidence levels for detection of impacts are
33 generally in the range of medium to high. The contribution of climate change to the detected impact varies
34 depending on the affected system, and climatic and non-climatic drivers. The highest levels of confidence for
35 attribution of detected impacts to anthropogenic climate change is assigned to the cryosphere. More
36 generally, those impacts are more strongly driven by increasing temperatures and show higher confidence for
37 attribution than those impacts mainly driven by precipitation changes. The level of contribution of climate
38 change to observed impacts is predominantly medium or high, indicating the high sensitivity of natural and
39 human systems in mountains to climate change. Furthermore, the vast majority of detected impacts imply
40 negative impacts on natural and human systems (high confidence).
41
42 Local knowledge plays an important role in documenting impacts of climate change in mountain regions.
43 Since IPCC AR5 the evidence of meaningful climate change impacts being reported using local knowledge
44 sources has increased substantially (high confidence). Similarly, important regional gaps present in the IPCC
45 AR5 have been addressed here (e.g. Africa), resulting in a much more comprehensive and regionally
46 balanced assessment and perspective.
47
48 Furthermore, the science of attributing negative impacts of climate change to anthropogenic emissions or
49 even individual polluters is becoming increasingly important for climate litigation (Marjanac et al., 2017;
50 McCormick et al., 2017; Otto et al., 2017; Setzer and Vanhala, 2019) and there is emerging evidence that
51 mountains are becoming sites of litigation cases, with cases for instance in Peru, Colombia, and India
52 (UNEP, 2017). Recent studies put litigation cases such as the Lliuya vs RWE case on risk of glacier lake
53 floods in Peru in a broader context of differentiated responsibilities and justice (Huggel et al., 2020b).
54
55
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1
2 Figure CCP5.4: Synthesis of detection and attribution of impacts of anthropogenic climate change on different natural
3 and human systems in mountain regions. For each system and region assessed, the level of confidence for detection and
4 for attribution to anthropogenic climate change is indicated. Also indicated is how strong the contribution of climate
5 change is to the observed changes, considering climatic and non-climatic causal factors. Observed impacts were
6 analysed in terms of negative impacts (e.g. economic or non-economic damages, losses, contribution to increasing risks
7 for society), where the numbers refer to the percentage of references indicating negative impacts for a given impact.
8 The percentage of local community perception indicates the percentage of all literature references for a given system
9 and region that account for local knowledge. The number of references refers to the total number of literature references
10 considered for an impact to a specific system and region. "Not assessed" refers to limited evidence in the literature (see
11 SMCCP5.2 and Table SMCCP5.5-5.14).
12
13
14 CCP5.2.7.2 Synthesis of Observed Adaptation
15
16 Extending from recent assessments of observed adaptation in high mountain areas (Hock et al., 2019;
17 McDowell et al., 2019) new evidence for the geographically larger space for mountains assessed in this CCP
18 is available from a mountain specific re-analysis of the GAMI dataset, which contains 423 articles reporting
19 adaptation in mountains (Berrang-Ford et al., 2021; McDowell et al., 2021b) (SMCCP5.3), some of which
20 also include those reported in section CCP5.2. In these articles, adaptation measures in mountains are
21 reported from all regions worldwide, with predominance from Asia and Africa. Of all reported adaptations,
22 91% involve individuals or households, frequently engaged in smallholder agriculture and/or pastoralism;
23 local governments are also often involved (31%) and sub-national or local civil society actors (29%) while
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1 private sector involvement remains scarce (below 10%). Food, fibre and other ecosystem products (76%) and
2 poverty, livelihoods and sustainable development (55%) are by far most often involved in reported
3 adaptation in mountains, followed by water and sanitation (28%) and health, well-being and communities
4 (26%) (McDowell et al., 2021b) (SMCCP5.3.2).
5
6 Adaptation measures most commonly found include farming-related changes (e.g. resilient or drought-
7 tolerant crop varieties, irrigation techniques, crop storage, and livestock insurance schemes), infrastructure
8 development, Indigenous knowledge, community-based capacity building, and ecosystem-based adaptation
9 (McDowell et al., 2021b) (SMCCP5.3.2) (high confidence). Nature-based solutions (NbS) are an adaptation
10 component in NDC's of many mountain countries around the world (UNEP, 2021). Furthermore, Indigenous
11 knowledge and local knowledge are often reported as informing adaptation efforts, and Indigenous Peoples,
12 marginalized people and gender issues are recognized in several national adaptation strategies but
13 autonomous responses are often insufficiently understood (Mishra et al., 2019).
14
15 The GAMI based re-analysis for mountains indicates that food security (75%), poverty (47%), consumption
16 and production (36%), terrestrial and freshwater ecosystem services (19%) and clean water and sanitation
17 (18%) are important aspects of vulnerability that adaptations address, with an emphasis on responses to
18 climate-related shocks and stressors (McDowell et al., 2021b) (SMCCP5.2). The re-analysis also shows that
19 more than 80% of adaptations in mountains are behavioural/cultural in nature, and more than 50%
20 ecosystem-based, or technological or infrastructural.
21
22 About a third of the assessed adaptation activities are in the planning and early implementation stage, and
23 around one-fifth in a stage of advanced implementation (McDowell et al., 2021b) (SMCCP5.3.2). Several
24 lines of evidence converge, indicating that most observed adaptation in mountains is incremental in nature
25 and not transformative (high confidence) (Mishra et al., 2019 ; McDowell et al., 2021b) (SMCCP5.3.2).
26 Nevertheless, some adaptation measures such as NbS were found to bear important transformative potential
27 in mountains if different knowledge types are combined, and community engagement and ecosystem
28 management processes are in place (Palomo et al., 2021).
29
30 Overall, and consistent with findings in SROCC, there are still limited systematic monitoring and evaluation
31 processes implemented to track adaptation progress, and there is limited evidence and prevailing
32 uncertainties on the extent to which observed adaptation efforts reduce risks (Hock et al., 2019; McDowell et
33 al., 2021b; UNEP, 2021) (SMCCP5.3.2).
34
35 Limits to adaptation are found in a majority (>80%) of the assessed adaptation studies; around half of the
36 studies reported soft limits and less than a third identified both hard and soft limits to adaptation (McDowell
37 et al., 2021b) (SMCCP5.3.2) (high confidence). Soft limits are frequently related to governance, economics,
38 and social/cultural constraints, and can be overcome in principle through targeted efforts to address social
39 conditions that impede adaptation planning and action. Hard limits are more frequently described as
40 biophysical, such as precipitous declines in water supply. Examples of adaptation limits include lack of
41 access to credit and markets, fixed livelihoods, insufficient awareness of climate risk, poor access to
42 technology, and the erosion of existing skills and knowledge, social inequities, lack of trust and social
43 cohesion, inequitable gender norms, and perceptions of conflict or scarcity. Furthermore, land tenure
44 insecurity, poor integration of adaptation programmes across governing scales, and lack of decision-making
45 power among vulnerable groups, along with inadequate funding for government-implemented adaptation
46 programmes are reported to limit adaptation (Mishra et al., 2019; McDowell et al., 2021b) (SMCCP5.3.2).
47 Hard limits imply that further adaptation action is unfeasible, ineffective, or unacceptable, resulting in
48 inevitable losses and damages in mountain areas (Huggel et al., 2019) (medium evidence, medium
49 agreement).
50
51 Overall, adaptation in mountain regions is taking place in various ways, in different sectors, scales, levels,
52 quality, and effectiveness (high confidence). Most responses are incremental, with asymmetries of power
53 among state, institutions and individuals, costs or capital requirements of adaptation, lack of coordinated
54 planning, resistance to institutional change, household risk aversion, and lack of access to information
55 inhibiting more transformational responses (SMCCP5.3.2). Aside from poverty reduction, there is limited
56 evidence of adaptations effectively remediating the underlying social determinants of vulnerability (e.g.
57 gender, ethnic identity).
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1
2
3 CCP5.3 Projected Impacts and Risks in Mountains
4
5 CCP5.3.1 Synthesis of Projected Impacts
6
7 Declines and extinctions have been projected in a range of montane plants and animal species, including rare
8 endemic species and subspecies due to climate change (medium evidence, high agreement) (Li et al., 2017;
9 Ashrafzadeh et al., 2019; Brunetti et al., 2019; Zhang et al., 2019b; Manes et al., 2021). Up to 84% of
10 endemic mountain species are found to be at risk of extinction (Manes et al., 2021). By using a simple
11 model, Helmer et al. (2019) predict a large-scale contraction in the next 25 years of alpine ecosystems above
12 tropical mountains cloud forest in the Andes due to tree invasion. Topographic complexity can smoothen and
13 delay transition of montane forests in terms of size and composition for warming up to 3°C GWL (Albrich et
14 al., 2020).
15
16 Hydrological changes will determine how some ecosystems change, more than changes in temperature. For
17 example, (Dwire et al., 2018) found that changes in riparian areas, wetlands and forests were likely under
18 climate change in the Blue Mountains, Oregon, USA, as a result of altered snowpack, hydrologic regimes,
19 drought and wildfire. In the Bolivian Cordillera Real, wetland cover variations were associated with
20 increases in precipitation extreme events and glacier melting over the 1984-2011 period but might be
21 reversed with predicted future decrease in both total precipitations and glacier run-off (Dangles et al., 2017).
22 About 30% of the wetland area in the Great Xing'an Mountains, northeastern China has been projected to
23 disappear by 2050, with this value doubling by 2100 under CGCM3-B1 scenario (Liu et al., 2011).
24
25 Climate change impacts on food, fibre and ecosystem products will be highly variable across mountain
26 regions (medium confidence) (Briner et al., 2013; Rasul and Hussain, 2015; Mina et al., 2017; Palomo, 2017;
27 Said et al., 2019; Xenarios et al., 2019) (Sections 10.4; 12.3; 13.5; 14.4). In some regions, tree crops that are
28 cultivated at certain elevations may reach the limit of their agroclimatic plasticity, for instance for crop types
29 that require winter chills and where projected growing conditions would be too warm (Buerkert et al., 2020).
30 In the European Alps, agricultural production in some areas may benefit from temperature rises, as total
31 productivity in grasslands is projected to increase (Mitter et al., 2015; Grüneis et al., 2018), whereas some
32 areas in Asia and South America heavily depended on glacier- and snow fed irrigation will be at risk of food
33 insecurity (Rasul and Molden, 2019). In a study in the Eastern Pamir, (Mtrak et al., 2017) found that
34 summer droughts and water changes lead to functional transformations of the wetland ecosystems which can
35 affect food security of the local population. Climate change affects the phenology of plants (Harish et al.,
36 2012; Gaira et al., 2014; Maikhuri et al., 2018), secondary metabolites (Chang et al., 2016; Kumar et al.,
37 2020), and pharmacological properties of medicinal plants (Gairola et al., 2010; Das et al., 2016).
38
39 Water resources in mountains and dependent lowlands will continue to be strongly impacted by climate
40 change throughout the 21st century (high confidence). The difference in impacts will be particularly strong
41 for regions that highly depend on glacier and snow melt, and in pronounced dry seasons (high confidence),
42 regions including Central Asia, South Asia, tropical and subtropical western South America, and
43 southwestern North America (Huss and Hock, 2018; Hock et al., 2019; Immerzeel et al., 2020). Glaciers are
44 expected to continue to lose mass throughout the 21st century, with higher mass loss under high emission
45 scenarios (AR6 WGI Chapter 9). Many low elevation and small glaciers around the world will lose most of
46 their total mass at 1.5°C GWL (high confidence) (Marzeion et al., 2018; Vuille et al., 2018; Hock et al.,
47 2019; Zekollari et al., 2020) (WGI 9.5). For tropical and mid-latitude mountains, around half of the current
48 ice mass can be preserved under low-emission scenarios, while two-thirds up to more than 90% will be lost
49 under high emission scenarios compared to the 2000's (medium confidence) (Schauwecker et al., 2017;
50 Vuille et al., 2018; Hock et al., 2019) (WGI 9.5). Strong differences in impacts between the emission
51 scenarios are also assessed for decline in snow depth or mass at lower elevation [10 to 40% for RCP2.6 and
52 50 to 90% for RCP 8.5 by the end of the century (Hock et al., 2019)]. However, limitations in long-term
53 climate, glaciological and hydrological monitoring data adds uncertainty to current understanding and
54 adaptation support, e.g. when peak water is reached in different mountain catchments (Salzmann et al., 2014;
55 Hock et al., 2019). Furthermore, context specific socio-cultural and economic factors can magnify, or
56 moderate impacts related to hydrological change (McDowell et al., 2021a).
57
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1 The dependence of lowland populations on mountain water resources will grow by mid-century across
2 several climate and socio-economic scenarios, and several seasonally dry or semi-arid mountain regions (e.g.
3 parts of South Asia, North America) are projected to be highly dependent (medium confidence) (Viviroli et
4 al., 2020) (Figure CCP5.2). Changing sediment, nutrient and pollutant flows due to climatic and non-climatic
5 drivers will impact populations and economic sectors (medium evidence, high agreement). Hydropower in all
6 mountain regions will experience higher flux of water and sediment in some seasons, but lower water flow
7 with demands from other water uses (e.g., irrigation) (Chevallier et al., 2011) in other seasons (Beniston and
8 Stoffel, 2014; Gaudard et al., 2014; Majone et al., 2016; Caruso et al., 2017a; Caruso et al., 2017b; Patro et
9 al., 2018). Recharge from groundwater and its buffer function is expected to decrease on the longer term
10 (Somers and McKenzie, 2020). Glacier and snow depth or mass decline will impact current hydropower
11 facilities and production in various complex ways, requiring changes in hydropower management, with
12 further potential for evidence informed solutions (Gaudard et al., 2014; Schaefli, 2015; Schaefli et al., 2019).
13 On the other hand, deglaciation in mountain regions opens topographic space and thus potential for
14 additional long-term hydropower development and production (Haeberli et al., 2016a), with an estimated
15 additional production of up to several hundred terawatt-hour per year, a potentially important contribution to
16 national energy supplies, in particular in the High Mountain Asia region (Farinotti et al., 2019). However,
17 water supply from glacier melt will decrease once source glaciers pass peak discharge (Huss and Hock,
18 2018), and the areas with available sediment will grow as glaciers shrink, posing potential risks to
19 downstream populations and assets (Lane et al., 2019) (high confidence).
20
21 Since SROCC (Hock et al., 2019), several new studies have addressed projected impacts of future climate
22 change on snow reliability in ski resorts, complementing previous findings or bridging existing knowledge
23 gaps for winter tourism. This includes, in particular, new studies for China (An et al., 2019; Fang et al.,
24 2019), showing that average ski seasons are projected to shorten (-4 to -61% for RCP4.5; -6 to -79% RCP8.5
25 in the 2050s) along with increases in snowmaking water demand (27 to 51% for RCP4.5; 46 to 80% for
26 RCP8.5 in the 2050s), with large differences across the country. Changes in future snow reliability are
27 projected across Europe at the national or pan-European scale (Demiroglu et al., 2019; Steiger and Scott,
28 2020; Morin et al., 2021), highlighting strong contrasts at the local (across ski resorts size and/or elevation
29 range, or local social or environmental context) and continental scales. Higher latitude and high elevation
30 locations generally exhibit delayed declines in snow reliability compared to lower latitude and lower-
31 elevation locations (high confidence), consistent with assessment conclusions reached in SROCC (Hock et
32 al., 2019). In general, climate change impacts and risks to ski tourism are found to be spatially
33 heterogeneous, within and across local and international markets, with potential for significant disruptions to
34 related socio-economic sectors due to a growing mismatch between ski area supply and skier demand in the
35 coming decades (Fang et al., 2019; Hock et al., 2019; Steiger et al., 2020a) (high confidence). These
36 disruptions are plausible, even though a fraction of current ski resorts could technically be able to operate
37 under comparatively favourable locations (elevation, latitude) and operating models (business models, socio-
38 cultural assets and conditions, governance) (Steiger et al., 2020b).
39
40 Severe damage and disruptions to people and infrastructure from floods are projected to increase in
41 Northwestern South America (NWS), South Asia (SAS), Tibetan Plateau (TIB) and Central Asia (WCA)
42 between 1.5°C to 3°C GWL mainly driven by river floods and an increase in the number of glacial lakes
43 with high potential for outburst (high confidence) (Drenkhan et al., 2019; Motschmann et al., 2020b; Furian
44 et al., 2021; Zheng et al., 2021). For example, the formation of new lakes at the foot of steep icy peaks
45 largely extends the hazard zones with respect to the earlier situation without lakes (Haeberli et al., 2016b).
46 Projected changes in ice and snow-melt, as well as seasonal increases in extreme rainfall and permafrost
47 thaw, will favour chain reactions and cascading processes which can have devastating downstream effects
48 well beyond the site of the original event (Cui and Jia, 2015; Beniston et al., 2018; Terzi et al., 2019; Vaidya
49 et al., 2019; Shugar et al., 2021) (high confidence). The incidence of disasters is projected to increase in the
50 future due to some hazards becoming more pervasive, with an increase in the exposure of people and
51 infrastructure with future environmental and socio-economic changes either contributing to reduce or
52 enhance these disaster risks (Klein et al., 2019b) (medium confidence).
53
54 CCP5.3.2 Key Risks Across Sectors and Regions
55
56 Key risks are derived from the detection and attribution assessment (CCP5.2.7) and from the projected
57 impact and risks (CCP5.3.1). The assessment is informed by evidence in the regional and sectoral chapters
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1 and supports the key risk assessment in Chapter 16. Four key risks (KR1 to KR4) have been identified in this
2 CCP and are presented in Sections CCP5.3.2.1-CCP5.3.2.4 (see SMCCP5.4 for methodology and
3 references).
4
5 CCP5.3.2.1 KR1: People and Infrastructures at Risks from Landslides and Floods
6
7 The amount of people and infrastructure at risk of landslides will increase in regions where the frequency
8 and intensity of rainfall events is projected to rise (Gariano and Guzzetti, 2016; Haque et al., 2019). Extreme
9 precipitation in major mountain regions is projected to increase leading to consequences such as floods and
10 landslides (AR6 WGI TS, medium confidence). Rain-on-snow events which can accelerate all flood stages
11 and result in widespread consequence for societies are projected to increase between 2-4°C GWL (but
12 decrease afterwards) (SROCC Chapter 2; WG I Chapter 12). There is high confidence that glacial retreat,
13 slope instabilities and heavy precipitation will affect landslides and flood activities although for landslides
14 there are considerable uncertainties in the direction of change (Patton et al., 2019) (AR6 WGI Chapter 12).
15
16 Future risk consequences which are considered severe include for example an increase of 10-20% compared
17 to present of the population exposed to landslides activities in certain regions (e.g. High Mountain Asia)
18 (Kirschbaum et al., 2020). This does not consider the expected increase in landslide activity relating to
19 glacier and permafrost changes (Picarelli et al., 2021) (see SROCC Chapter 2) and therefore it is expected to
20 be a conservative estimate. Other severe consequences are on average a projected twofold increase in the
21 number of people exposed to inland flooding between 2°C and 4°C with highest increases in South Asia,
22 Southeast Asia and South America (high confidence in the direction of change and medium confidence in the
23 absolute values because based on global studies) (Hirabayashi et al., 2013; Allen et al., 2016; Arnell and
24 Gosling, 2016; Zheng et al., 2021). Therefore, high to very high risks are expected between 2°C and 4°C
25 GWL in several mountain regions (Figure CCP5.5 red and violet shaded bars). Many regions are projected to
26 experience high risks due to the timing (potentially for severe consequences to happen sooner rather than
27 later), the magnitude in terms of number of people and infrastructure affected) and the persistence of hazard
28 conditions (Figure CCP5.5, AR6 WGI Chapter 12). Comparatively, more severe risks consequences are
29 expected under SSP3 and/or SSP4 given the high population projections in certain regions compared to SSP1
30 (Kirschbaum et al., 2020) (see Figure CCP5.1) (medium confidence).
31
32
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1
2 Figure CCP5.5: People and infrastructure in mountain regions at risk from landslides and/or floods for various Global
3 Warming Levels (GWLs). Panel a) shows the level of risk assessed per AR6 WGI reference regions (see AR6 WGI
4 Atlas). For some mountain regions, there is limited evidence to adequately assess the level of risks against GWLs,
5 therefore this is labelled as "not assessed". Panel b) shows the level of risk aggregated at the continent scale and the
6 principal hazards for which evidence was available and assessed. Methodological details and traceability are provided
7 in SMCCP5.4, Figure SMCCP5.1, Table SMCCP5.15 and SMCCP5.17.
8
9
10 CCP5.3.2.2 KR2: Risks to Livelihoods and the Economy from Changing Water Resources
11
12 KR2 encompasses the relative and absolute dependency on water resources for economic activities and
13 livelihood sustainment in mountain regions and in the lowlands. Particularly affected by changes in water
14 resources will be regions with (seasonally) high dependence on snow and glacier melt, i.e. arid and semi-arid
15 zones in the Andes, Central Asia and the Upper Indus Basin (Huss et al., 2017; Huss and Hock, 2018;
16 Viviroli et al., 2020) (Section CCP5.3.1).
17
18 Consequences that are considered severe refer to the magnitude (number of people and economic activities
19 affected), the timing (increase of water stress as early as mid-century in several regions) and the likelihood
20 (severe risk consequences are more likely where high population density is projected) (see Figure CCP5.1,
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1 Figure CCP5.6, Section 4.2.2.3) (Fuhrer et al., 2014; Wijngaard et al., 2018; Biemans et al., 2019; Immerzeel
2 et al., 2020; Viviroli et al., 2020) (high confidence). Severe consequences are that by mid-century more than
3 a half of agriculture regions equipped for irrigation are projected to be dependent on mountain runoff and
4 could therefore be unsustainably using blue water (e.g. water from river, lakes and aquifers) (Viviroli et al.,
5 2020) or that the number of people being water stressed will increase by 50% to 100% in areas already water
6 stressed today (Munia et al., 2020). Hotspot regions are those with large lowland populations depending on
7 essential mountain water resource contributions and include river catchments such as Ganges, Brahmaputra,
8 Meghna, Yangtze, Nile, Niger, Indus, Euphrates-Tigris or Pearl (Viviroli et al., 2020) (high confidence) (see
9 Figure CCP5.6). Limited governance and integrated management of water resources, power and gender
10 inequalities and level of disruption of local community practices also contribute to make risks more severe
11 (medium confidence) (Lynch, 2012; Boelens, 2014; Wijngaard et al., 2018; Scott et al., 2019; Immerzeel et
12 al., 2020). Consequences for hydropower are comparatively less severe than for agriculture and
13 domestic/municipal use although this depends on region and timing (see also Section 5.2.2.2). For example,
14 a study shows low risk to hydropower production in High Mountain Asia until the end of the century and
15 even for warming levels beyond 3°C (Mishra et al., 2020) (robust evidence, moderate agreement).
16
17 Large scale and transformative interventions can reduce the high-end impacts of changing water resources
18 and in particular the risks of water scarcity (see Section CCP5.4.1). These interventions have long lead times,
19 are costly and may face institutional constraints (see Section 4.5.3), resulting in adaptation shortfall.
20 Therefore, high to very high-risk levels cannot be excluded in regions where other key risks characteristics
21 such as magnitude, timing and likelihood are assessed as high due to potential losses (e.g. in many Asian
22 regions, see Figure CC5.6, SMCCP5.4 and Table SMCCP5.16).
23
24
25
26 Figure CCP5.6: Risk levels assessed per AR6 WGI reference regions (see AR6 WGI Atlas). The majority of studies
27 assessed focus on impacts up to mid-century (2030-2060) and for RCP-2.6, RCP-4.5 and RCP-6.0, which was
28 converted into the corresponding warming level range 1.5-2.0°C GWL (see Cross-Chapter Box CLIMATE in Chapter
29 1). Methodological details are provided in Section SMCCP5.4, Figure SMCCP5.1, Table SMCCP5.16 and
30 SMCCP5.18. Due to the limited evidence available to determine risks against high Global Warming Levels (GLWs),
31 and the relatively high uncertainties associated with future irrigation trends for the second half of the century (see e.g.
32 Viviroli et al., 2020), assessment of risks associated with GLWs greater than 2.0°C GWL was not conducted.
33
34
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1 CCP5.3.2.3 KR3: Risks of Ecosystem Change and Species Extinction
2
3 Risks to mountain ecosystems and the services they provide to people are varied in magnitude, timing,
4 likelihood and potential to adapt and place specific (see Table SMCCP5.19). However, many mountain
5 ecosystems are already showing impacts of climate change (CCP5.3.1), reflecting the strong influence
6 climate has in many situations and indicative that risks are large, immediate and will likely increase in the
7 near as well as long-term. There is robust evidence (high agreement) of vegetation zones and individual
8 species shifting to higher elevations (Section 5.2.1; Chapter 2.4) and projections indicate that current will
9 continue and accelerate at higher rates of warming (medium evidence, high agreement) (Section 2.5).
10
11 Many mountain species are at risk of range contraction and ultimately extinction if dispersal at the upper
12 range limit is slower than losses due to mortality at the lower range limit (observed for trees in the
13 Neotropics; (Feeley et al., 2013; Duque et al., 2015), or if mountains are not high enough to allow species to
14 move to higher elevations. Ramirez-Villegas et al. (2014) modelled 11,012 species of birds and vascular
15 plants in the Andes, finding large decreases by 2050 (SRES-A2 scenario); in absence of dispersal 10% of
16 species could become extinct. Even assuming unlimited dispersal, most of the Andean endemics would
17 become severely threatened. Other modelling studies have also projected declines in a range of communities
18 and species, including rare endemics (Zomer et al., 2014a; Rashid et al., 2015; Bitencourt et al., 2016; Li et
19 al., 2017; Rehnus et al., 2018; Ashrafzadeh et al., 2019; Zhang et al., 2019b; Cuesta et al., 2020; Hoffmann
20 et al., 2020).
21
22 Many treelines will continue to shift to higher elevations with increasing temperatures (Chhetri and Cairns,
23 2018), although very few are changing as fast as climate change (Liang et al., 2016; Hansson et al., 2021)
24 and some are not moving or even shifting to lower elevations (CCP5.2.1). If treelines fail to shift uphill, this
25 presents a risk for species of the upper-montane forest that experience range contraction at their lower range
26 limit but lack a suitable habitat to expand into beyond their upper range limit (Rehm and Feeley, 2015).
27 Changes in phenology can also present risks to species and ecosystems (Chapter 2), including a potential
28 desynchronization of mutualistic relationship such as pollination and increased freezing damage due to
29 premature emergence from winter dormancy. In European broadleaved trees, for example, the upper
30 elevational limits of different species involve a trade-off between maximizing growing season length and
31 limiting the risk of spring freezing damage (Vitasse et al., 2012; Körner and Spehn, 2016).
32
33 A wide range of mechanisms can cause changes within ecological communities, some of which are hard to
34 predict but there are an increasing number of studies illustrating some of the risks which are expected to be
35 most common. If treelines shift upwards, this presents a risk for alpine species, which cannot compete with
36 trees. This may lead to extinction of alpine species on mountains where there is insufficient room for the
37 alpine zone to shift uphill. Shifts in species distributions, and in particular shifts in ecosystem types, can
38 cause changes in ecosystem function, which may in turn have cascading impacts on people, for example
39 leading to increased exposure to diseases such as malaria at high elevation (Section 2.4.2.7.2) as vector
40 distribution changes and wider impacts on ecosystem services (Section 2.5.3) such as water supply, flood
41 alleviation and food.
42
43 CCP5.3.2.4 KR4: Risk of Intangible Losses and the Loss of Cultural Values
44
45 The risk of intangible losses and loss of cultural values is associated with the decline of ice and snow cover
46 and temperature increase, as well as the increase in intangible harm from hazards such as floods and
47 droughts (high agreement, medium evidence) (Diemberger et al., 2015; Jurt et al., 2015; Vuille et al., 2018;
48 Tschakert et al., 2019; Vander Naald, 2020). Losses are intangible because they characterise aspects which
49 are difficult to quantify, i.e. loss of identity, loss of self-reliance, loss of rituals and traditions and place
50 attachment (Allison, 2015; Baul and McDonald, 2015; Motschmann et al., 2020a; Schneiderbauer et al.,
51 2021). A global systematic analysis of case studies shows that this risk is more prevalent in the Andes, the
52 Himalaya and the Alps (Tschakert et al., 2019). Often mentioned across studies is the loss of intrinsic
53 memories and culture related to changes in world heritage landscapes and iconic sites (Jurt et al., 2015;
54 Sherry et al., 2018; Bosson et al., 2019). Changes in the hazard landscapes are also reported to contribute to
55 the loss of peace of mind and loss of well-being (Diemberger et al., 2015). Overall, there is limited evidence
56 but medium agreement that the risk of intangible losses and the loss of cultural identity will rapidly increase
57 and that consequences will go from reversible damage to irreversible losses (Tschakert et al., 2019).
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1
2
3 CCP5.4 Options for Adaptation and Climate Resilient Development Pathways
4
5 CCP5.4.1 Synthesis of Adaptation Responses to Reducing (Key) Risks
6
7 More than half of the studies having a focus on mountains (423 articles) extracted from the GAMI dataset
8 report that adaptation responses are contributing to reducing climate risks (Berrang-Ford et al., 2021;
9 McDowell et al., 2021b) (see SMCCP5.3.2). However, the extent of adaptation in terms of time (i.e. speed),
10 the scale of change (i.e. scope) and its depth (i.e. degree to which a change is substantial) is low in mountain
11 regions, with the level of agreement across studies varying from one region to the other (medium confidence)
12 (Figure CCP5.7, SMCCP5.3.2). In regions where risk levels remain moderate, a low adaptation extent might
13 be sufficient to constrain risks (see Figure CCP5.5 and Figure 5.6; Section 16.3.2.5).
14
15 Adaptation responses in mountains are mainly incremental changes from existing practices (high confidence)
16 (McDowell et al., 2019; Rasul et al., 2020; McDowell et al., 2021b), signalling that the potential of current
17 and planned adaptation responses to reduce risks in the future will not be adequate to mitigate high to very
18 high risks. For example, measures to contain floods or landslides (KR1) are designed with specific
19 magnitudes and types in mind often assuming stationarity of return periods (Montanari and Koutsoyiannis,
20 2014; Gariano and Guzzetti, 2016). In the case of events showing decreasing return periods, risk mitigation
21 standards need to be elevated to provide for more protection in the future (Felder et al., 2018; François et al.,
22 2019). The portfolio of adaptation options to mitigate risks from changing water resources (KR2) is large but
23 challenging and includes integrated catchment management, implementation of multiple use of water
24 strategies, improved water governance (including community based and participatory water governance),
25 overcoming power inequalities among users and sectors, and balancing economic pressure and sustainable
26 development (high confidence) (Bekchanov and Lamers, 2016; Yapiyev et al., 2017; Jalilov et al., 2018;
27 Drenkhan et al., 2019; Allen et al., 2020; Aggarwal et al., 2021; Huang et al., 2021) (SMCCP5.3.2). There is
28 limited evidence on the effectiveness of adaptation responses to reduce the severity of ecosystem change
29 (KR3) (also see Section 16.3.1). Prevention rather than control and eradication efforts can contribute to
30 curbing biological invasions of alien species in the short turn, whereas colonisation by native trees following
31 land use abandonment can be more effective in the long run (Carboni et al., 2018). Reducing intensified
32 grazing, agricultural expansion, and conservation management in buffer zones of protected areas can limit
33 the altitudinal range shift of endemic species (Kidane et al., 2019).
34
35 EbA has been effective in mountain regions to reduce risks from floods (e.g. restoration of buffer zones and
36 floodplains) and landslides (e.g. protective forests) (Muccione and Daley, 2016; Klein et al., 2019b; Lavorel
37 et al., 2019). Ecosystem based measures have been implemented for water management purposes to supply
38 clean water and improve water quality (see Section 4.5.2.1). Furthermore, they provide scope for
39 conservation and improvement of habitats, e.g. forest ecosystems (Nagel et al., 2017; Lamborn and Smith,
40 2019) (high agreement, medium evidence). However, repeated, and recurrent disturbances that increase
41 recovery times can reduce the effectiveness of EbA (Sebald et al., 2019; Scheidl et al., 2020) (medium
42 confidence).
43
44 Adaptation in mountain areas is currently constrained predominantly by soft limits related to existing social,
45 economic, and political conditions (high confidence) (Gioli et al., 2014; Sansilvestri et al., 2016). Progress in
46 overcoming soft limits is currently minimal due to insufficient engagement with socio-economic and
47 political issues in existing adaptation (medium confidence) (McDowell et al., 2019; McDowell et al., 2021b)
48 (Sections 8.4.5.3, Cross-Chapter Box LOSS in Chapter 17). This is expected to lead to an expansion of
49 residual risks as risk severity increases (McDowell et al., 2021b).
50
51
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1
2 Figure CCP5.7: Extent of planned and implemented adaptation actions observed in mountain regions shown in terms
3 of three dimensions: i) speed (timeframe within which adaptations are being implemented), ii) scope (the scale of
4 changes observed from the adaptation action), and iii) its depth (i.e., degree to which a change reflects something new)
5 (see Section 16.3.2.5). The data are obtained from the Global Adaptation Mapping Initiative (GAMI) re-analysis for
6 mountains (see SMCCP5.3.2 and Berrang-Ford et al., 2021; McDowell et al., 2021b).
7
8
9 CCP5.4.2 Challenges, Opportunities and the Solution Space for Adaptation in Mountains
10
11 The effects of climate change on mountain environments pose significant challenges for people, ecosystems,
12 and sustainable development, with issues such as difficult access, environmental sensitivity, and socio-
13 economic marginalization making adaptation particularly complex. Furthermore, varied and dynamic
14 biophysical characteristics as well as high socio-cultural diversity preclude one-size-fits-all responses;
15 adaptation planning and action in mountains rooted in context-specific socio-ecological and climatic realities
16 are more effective (Hock et al., 2019; Lavorel et al., 2019; McDowell et al., 2020) (high confidence). Despite
17 these challenges, there is growing evidence of opportunities for advancing effective responses to climate
18 risks in mountain areas (McDowell et al., 2020) (Section 16.3; Cross-Chapter Box NATURAL in Chapter 2).
19
20 The solution space for adaptation represents a realm of possibility for addressing climate risks; it is shaped
21 by both socio-economic and climatic factors that influence who adapts, when they adapt, and how they adapt
22 to climate change (Haasnoot et al., 2020) (Sections 1.5.1 and 17.4). The space includes both planned and
23 autonomous responses (Hock et al., 2019; McDowell et al., 2019). Autonomous response can be appropriate
24 when local resilience is high (Mishra et al., 2019; Ford et al., 2020); however, many mountain communities
25 continue to face socio-economic challenges that constrain their adaptive capacity (high confidence). Planned
26 adaptations are a critical component of the solution space, although external interventions can also reinforce,
27 redistribute, or create new vulnerabilities when they proceed without sincere engagement with local
28 communities (Eriksen et al., 2021). The solution space also evolves as social and climatic conditions change
29 and can be capped by social and biophysical limits to adaptation that render further responses to climate
30 change inaccessible, unfeasible, or ineffectual. Such limits are already observed and are likely to become
31 more widespread as climatic stressors move beyond historical experience (IPCC, 2018; Hock et al., 2019;
32 McDowell et al., 2020) (Section 17.3; Cross-Chapter Box DEEP in Chapter 17) (high confidence).
33
34 Evidence shows the significant potential of adaptation actions such as Nature-based Solutions or multiple use
35 of water approaches but with a need to carefully evaluate environmental, economic and social co-benefits,
36 trade-offs (Yang et al., 2016; Drenkhan et al., 2019; Lavorel et al., 2019; McDowell et al., 2019; Palomo et
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1 al., 2021) (high agreement, medium confidence). The potential for adaptation to contribute to sustainable
2 development and transformative change in mountains is also becoming increasingly evident (Palomo et al.,
3 2021) (medium confidence), yet there is currently limited evidence with respect to the long-term
4 effectiveness of adaptations in achieving such outcomes (Balsiger et al., 2020). To better achieve the
5 adaptation potential in mountains, adaptation finance and private sector inclusion and contribution are key
6 enablers (Mishra et al., 2019; UNEP, 2021) (high confidence).
7
8 There is increasing recognition that inclusive and comprehensive adaptation approaches can be more
9 successful (Allen et al., 2018; Hock et al., 2019; Huggel et al., 2020a; Huggel et al., 2020b) (medium
10 evidence, high agreement). Stakeholders such as local communities and government entities often prioritize
11 different dimensions of climate related risks (López et al., 2017; McDowell et al., 2020). Adaptation
12 initiatives that identify locally-relevant climate stressors and risks through knowledge co-production have the
13 potential to be more acceptable and effective (medium evidence, high agreement) (Huggel et al., 2015;
14 Muccione et al., 2016; Allen et al., 2018; Quincey et al., 2018; Balsiger et al., 2020; McDowell et al., 2020;
15 McDowell et al., 2021b) (Cross Chapter Box DEEP in Chapter 17). However, tenable co-production requires
16 recognition of the validity and integrity of diverse knowledges systems, including those held by Indigenous
17 Peoples and local communities, as well as the provision of sufficient time and resources for meaningful
18 engagement between stakeholder groups (Howarth and Monasterolo, 2016; Bremer and Meisch, 2017;
19 Schoolmeester and Verbist, 2018; McDowell et al., 2019; Ford et al., 2020). Power imbalances and
20 knowledge politics continue to impede the inclusion of historically underrepresented voices in adaptation
21 planning and action(Ojha et al., 2016; Mills-Novoa et al., 2017). Citizen science plays an additional role in
22 facilitating the inclusion of multiple knowledges (Buytaert et al., 2014; Dickerson-Lange et al., 2016;
23 Tellman et al., 2016; Njue et al., 2019).
24
25 Progress in addressing climate risks requires targeting the root causes of vulnerability, which are often socio-
26 economic in origin and can include poverty, marginalization, and inequitable gender dynamics (Ribot, 2014;
27 Carey et al., 2017; Shukla et al., 2018; McDowell et al., 2019) (high confidence). Promoting resilience in
28 many mountain regions requires responses that address the social determinants of susceptibility to harm.
29 Context-specific manifestations of such determinants (and leverage points for positive action) can be
30 identified through participatory processes with affected populations, with action on social determinants of
31 climate change vulnerability having important co-benefits for equity, justice, and sustainability. Addressing
32 the root causes of vulnerability can also resolve soft limits to adaptation, thereby increasing the solution
33 space (McDowell et al., 2020).
34
35 There is growing evidence of the potential for coordination and monitoring networks to overcome existing
36 data deficiencies, to fill knowledge gaps, and to streamline implementation, all of which currently impede
37 adaptation in mountains (Salzmann et al., 2014; Muccione et al., 2016; Ryan and Bustos, 2019; McDowell et
38 al., 2020; Shahgedanova et al., 2021; Thornton et al., 2021; Price et al., Accepted/In press). Furthermore,
39 there is increasing evidence that key conventions related to mountains, such as the Alpine Climate Board
40 (SROCC 2.4), provide opportunities for accelerating adaptation efforts through mainstreaming responses
41 into other policies aimed at addressing climate-related risks (Balsiger et al., 2020) (medium confidence).
42 Regional cooperation among countries and transboundary landscape and river basin governance initiatives
43 are an important mechanism for advancing adaptation in mountains (Molden et al., 2017; Mishra et al., 2019;
44 Balsiger et al., 2020) (high agreement, medium evidence), particularly as many mountain ranges and
45 mountain ecosystem services are transboundary in nature.
46
47 Access to major adaptation support programs such as through the UNFCCC, national governments, multi-
48 and bi-lateral aid arrangements, the private sector, and non-governmental organizations (NGOs) has been
49 relatively limited to support adaptation action in mountain regions, indicating significant unutilized support
50 options for increasing the solution space in mountains (McDowell et al., 2020). Enhanced uptake of available
51 support and funding could help to ease the adaptation burden for mountain communities. This will require
52 addressing soft limits to adaptation, which currently constrain the ability of actors to identify, access, and
53 mobilize resources for planned adaptations (McDowell et al., 2020).
54
55 More inclusive adaptation approaches, engagement with the root causes of vulnerability, improved
56 coordination and monitoring activities, and upscaling of support for adaptation are key enablers and are
57 indicative of a substantial solution space for adaptation in mountains regions (high confidence). However,
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1 trajectories of climate change and the prospect of hard limits to adaptation, which are often biophysical in
2 origin, portend climate futures that could overwhelm adaptation efforts. Success therefore hinges on
3 increasing the quality and quantity of adaptation efforts, including through transformative action, as well as
4 enhanced mitigation efforts, consistent with the recommendations of IPCC SR 1.5C (IPCC 2018) (Cross-
5 Chapter Box PROGRESS in Chapter 17).
6
7 CCP5.4.3 Climate Resilient and Sustainable Development in Mountains
8
9 With accelerating warming and compounding risks increasing above 1.5oC warming, the need for climate
10 resilient development in mountains is evident, and intricately linked to achieving the SDGs and equity (high
11 confidence). In this context, Chapter 18 draws attention to climate resilient development pathways (CRDP),
12 as processes that strengthen sustainable development and efforts to eradicate poverty and reduce inequalities
13 while promoting fair and cross-scalar adaptation and mitigation. Pathways that strengthen climate-resilient
14 sustainable mountain development are starting to receive attention (Chelleri et al., 2016; Trabacchi and
15 Stadelmann, 2016; AlpineConvention, 2021). This section treats four domains of emerging evidence related
16 to climate resilient development in mountains: 1) climate actions that support both adaptation and mitigation;
17 2) Indigenous knowledge and local knowledge in support of climate resilient development; 3) climate
18 resilient development in climate policy and planning; and 4) mainstreaming of climate action into
19 development pathways.
20
21 Nature-based Solutions (NbS) can be pursued in mountains that will mitigate climate change and its impacts
22 while at the same time contributing to improving livelihoods, social and economic well-being, and
23 sustainable environmental management (high confidence). A global review of 93 Nature-based Solutions in
24 mountains, such as afforestation, protection of existing forests, agroforestry and climate smart agriculture,
25 confirm the potential of NbS for change towards sustainable trajectories (Palomo et al., 2021). Agroforestry
26 is widely cited for delivering on food security as well as increasing resilience and mitigating climate change
27 (Mbow et al., 2014; Amadu et al., 2020; Gidey et al., 2020). Also, the prudent use of biomass for wood-
28 based bioenergy in mountains can mitigate the impacts of climate change, reduce vulnerability to disturbance
29 events such as fires, and enhance rural socioeconomic development (Beeton and Galvin, 2017). Yet, there
30 can be trade-offs contingent upon place-based and context-specific social and environmental factors, such as
31 between the use of bio-energy, agricultural production and conservation concerns (Beeton and Galvin, 2017).
32 Evidence from the world's mountains highlights the importance of cross-scale partnerships and
33 interdisciplinary, bottom-up approaches that facilitate stakeholders in envisioning locally tailored, climate-
34 resilient and sustainable development pathways (Chelleri et al., 2016; Capitani et al., 2019; Klein et al.,
35 2019b; Pandey et al., 2021).
36
37 Mountains are the home of many cultures and diverse Indigenous knowledge and local knowledge (systems),
38 which can and do provide strong support for place-based integrated adaptation and mitigation strategies
39 (Merino et al., 2019). Indigenous knowledge and local knowledge reinforce community adaptive capacity,
40 yet governance structures and processes, including the deliberate design and implementation of climate
41 policy, can constrain that capacity from being realised (Hill, 2013; McDowell et al., 2014; Wyborn et al.,
42 2015; Klepp and Chavez-Rodriguez, 2018; Lavorel et al., 2019) (high confidence). Communities,
43 particularly poor and remote mountain communities, are vulnerable to climate change and there is a need for
44 capacity building in research, policy development and implementation for pursuing climate resilient
45 development (Manton and Stevenson, 2014). Climatic stressors and socio-economic changes are changing
46 traditional genderscapes in mountain communities (Goodrich et al., 2019). There is increasing evidence on
47 the roles that gendered diversity in knowledge, institutions, and everyday practices can play in addressing
48 barriers and creating opportunities for achieving resilience, adaptive capacity and sustainability in societies
49 (Gioli et al., 2014; Ravera et al., 2016; Su et al., 2017; Udas et al., 2018; Goodrich et al., 2019; Sujakhu et
50 al., 2019).
51
52 Concerning climate policy and planning for climate resilient development in mountains, a review of
53 mountain specific priorities in the National Adaptation Programmes of Action (NAPA) submitted to the
54 UNFCCC shows that countries have prioritized improving agricultural outputs by introducing climate smart
55 crops and upgrading and building climate resilient irrigation infrastructure (UNFCCC, 2020c). Countries that
56 have submitted their NAPs to the UNFCCC have prioritized improving ecosystem resilience through
57 conserving agro-biodiversity in mountains. Countries have also focused on achieving food security in
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1 mountain regions and laying the foundations for food availability, stability, access and safety amidst
2 increasing climate risks (UNFCCC, 2020a).
3
4 In the Nationally Determined Contributions (NDCs) where mountain regions are specifically mentioned,
5 countries have prioritized climate resilient solutions, including, developing a low carbon green economy
6 through implementing low carbon transport systems and encouraging sustainable waste management
7 practices, as well as developing infrastructure for climate resilient agriculture, the sustainable management
8 of forests and the conservation of biodiversity. Several countries have specifically pledged to build climate
9 resilient mountain infrastructure taking into account future climate uncertainties. Countries have also
10 identified the need for capacity building of national stakeholders and have pledged to provide relevant
11 climate information (UNFCCC, 2020b).
12
13 Similar pledges are announced in formal institutional arrangements such as the Alpine Convention and the
14 Carpathian Convention. The Alpine Convention's climate action plan prioritises reaching climate-neutral and
15 climate resilient Alps by 2050. For this, implementation pathways on specific sectors have been identified
16 ensuring coherence to global and regional goals such as the Paris agreement, SDGs, EU legislations and
17 climate laws (AlpineConvention, 2021). Likewise, the Carpathian Convention's working group on climate
18 change has presented a long-term vision towards combating climate change thorough amending the article of
19 the convention to focus specifically on climate change adaptation and mitigation (CarpathianConvention,
20 2020).
21
22 Sustainable and climate resilient mountain development is predicated on effective and timely climate action
23 building on cross-scalar partnerships among researchers, stakeholders, and decision makers to jointly
24 identify desired futures and pathways and assess trade-offs and synergies between climate action and the
25 SDGs (Klein et al., 2019a; Pandey et al., 2021) (high agreement, medium evidence). Understanding of the
26 complexity of mountain ecosystems as well as path-dependency from earlier and current decisions is of
27 critical importance for the sustainable future of mountain regions (Satyal et al., 2017; Chanapathi and
28 Thatikonda, 2020; Berkey et al., 2021). Framing pathways through questions such as "to whom or to what is
29 climate action positive" and "which trade-off should be accepted, and why" can serve as a tool for
30 addressing sustainable development goals, while avoiding lock-ins or unsustainable path dependencies
31 (Chelleri et al., 2016). Increasingly, climate action is mainstreamed into sustainable development, which
32 signifies a shift from climate policy as an end-point to a continuing process for managing change and
33 facilitating long-term sustainable development. The Ethiopian government's Climate Resilient Green
34 Economy (CRGE) strategy is an example of such a shift (Simane and Bird, 2017) as are emerging initiatives
35 to build-back-greener in response to COVID-19 impacts (Schipper et al., 2020).
36
37
38 CCP5.5 Key Assessment Limitations and Relevant Knowledge Gaps
39
40 The assessment presented in this CCP has several limitations, principally in terms of the amount, often
41 fragmented and biased geographic coverage, or lack of relevant thematic scope covered in the literature
42 published since AR5 and SROCC. Key assessment limitations and relevant knowledge gaps identified in this
43 CCP fall within the following broad categories: 1) detection and attribution of observed impacts to climate
44 change; 2) limitations and uncertainties associated with predictive models of projected impacts and risks; 3)
45 integrated and systems-oriented research on mountain ecosystem services and their limits under climate
46 change; and 4) measurable tracking of adaptation action implemented in mountain regions and their
47 suitability for addressing climate risks. These are summarised in Table CCP5.3. While these limitations and
48 assessment-relevant gaps in knowledge offer important caveats for the interpretation of this assessment, they
49 also highlight prospects to address and improve the evidence basis in future assessments.
50
51
52 Table CCP5.3: Summary of key assessment-relevant knowledge gaps and limitations identified in CCP5.
Key assessment-relevant knowledge gaps and limitations Relevant WGII
report sections
Detection and attribution of observed impacts to climate change
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Key assessment-relevant knowledge gaps and limitations Relevant WGII
report sections
Limited · While there is high confidence on the links between future impacts and risks
associated with climate change, there is medium evidence available on robust CCP5.2.7;
amount and detection and attribution of past changes in mountain regions. Figure CCP5.4;
Considerable assessment gaps exist given the limited scope (temporal,
scope of spatial, or thematic coverage) and number of published studies reporting data SMCCP5.2.
and information that capture how mountains social-ecological systems
literature · function, and their trends over the past decades, that may be applicable for CCP5.2.1;
detection and attribution of changes to climatic change. CCP1-
available on Additionally, there are limitations in current methodologies to include and
account for other knowledges with respect to detection and attribution of Biodiversity
impacts for impacts to climate change in mountain regions (e.g. Chakraborty and Sherpa, Hotspots
2021).
assessment of
detection and
attribution to ·
climate change.
Consequences of · The net effects of ongoing climate change with treeline advance and
shifting treelines vegetation change on ecosystem carbon exchange, or possible effects on
and their mountain hydrology, remain unresolved in the literature.
interactions with · Uncertainties remain regarding effects to ecosystem-level carbon storage,
other ecosystem given that above-ground biomass is higher in forests than in alpine vegetation
functions and (new) trees may change soil carbon fluxes, for instance by introducing
new soil organisms, thereby increasing soil carbon flux (e.g. Tonjer et al.,
· 2021).
Short- and long-term effects of combined warming and changed species
cover on mountain soils are complex and insufficiently quantified (Hagedorn
et al., 2019).
Limitations and uncertainties associated with predictive models of projected impacts and risks
Shared · There are relevant knowledge gaps in the understanding of future CCP5.3.1;
SMCCP5.1
socioeconomic vulnerabilities in mountain social-ecological systems in relation to highly CCP5.2.1
pathways variable and dynamic trends in projected demographic change, socio- CCP5.3.1
(SSPs) economic development pathways, and demands for resources.
Species · Species distribution models (SDMs), which rely on statistical correlations
distribution between occurrence records and environmental variables to make spatially
models (SDM) explicit predictions, are commonly used to project climate change impacts on
mountain ecosystems (Guisan et al., 2017).
· However, they are associated with some limitations that can limit their utility
to derive reliable predictions of future mountain vegetation distributions, and
therefore ability to provide a sound basis for mountain nature conservation
and climate change adaptation.
· In particular, they only indicate the potential future species distributions
based on the static relationships between species and predictors in the
calibration data; in reality, vegetation dynamics will be heavily modulated by
phenomena that are commonly overlooked by such models like changing
species interactions and competition due to variance in response rates
amongst different species, dispersal limitations, and demographic processes
(Scherrer et al., 2020).
· In addition, SDMs are often limited by data availability and therefore tend to
omit several environmental factors known to be important for plants such as
soil formation processes, disturbances (e.g. rockfalls, avalanches), and
microclimatic conditions (Scherrer et al., 2011; Enright, 2014; Mod et al.,
2015; Brĺthen et al., 2018).
· More complex dynamic and process-based models are available, but still
rarely represent all potentially influential vegetation co-variates; applying
both model types in conjunction demonstrates potential (Horvath et al.,
2021).
Quantifiable · There is limited evidence on climate-related risks to economic sectors that are
estimates of vital for mountain regions, specifically on quantifiable estimates of monetary
monetary costs costs and potential material losses for economic sectors and communities in
and potential mountains, adjacent lowlands, and other regions dependent on these
material losses economic activities.
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Key assessment-relevant knowledge gaps and limitations Relevant WGII
report sections
Other model · Ecological models which could allow to better forecast the effectiveness of
limitations EbA as NbS, under different climate scenarios, are not fully developed CCP5.4
(Seddon et al., 2020).
Integrated and systems-oriented research on mountain ecosystem services and their limits under climate change
Water · Few assessment-relevant integrative studies are available in the published CCP5.2.2
literature that address relevant aspects of water security, beyond water Chapter 4
availability from glacier-fed meltwater, or snow, groundwater, other water
stores, such as wetlands, sediments, etc. Likewise, few studies address
seasonality with respect to a more systems-oriented approach to supply (e.g.
water availability) and demand (irrigated agriculture, and other multiple uses
and user groups).
Measurable tracking of adaptation action implemented in mountain regions and their suitability for addressing climate
risks
Conditions · Few studies report on how adaptation measures and programmes function in CCP5.4.2
under which mountainous contexts that yield the outcomes reported (McDowell et al.,
adaptation 2020).
interventions
work against · Despite transformative processes, to date there is limited evidence of how
stated goals knowledge co-production activities support the planning and implementation
of successful adaptations in mountain areas.
Metrics and · Adaptation responses to intangible losses and loss of cultural values are CCP5.3.2.4;
heuristics for reported and take different forms as demonstrated in studies from different Section 4.4.3.3
tracking world regions (de la Riva et al., 2013; Wang and Qin, 2015; Vander Naald,
effectiveness 2020). However, there is limited evidence on their adequacy for addressing
increasing losses, which remains largely unexplored in the available
literature.
Methods and · Regarding adaptation efforts and effectiveness, there are considerable gaps in Section 17.5;
adequate monitoring and appropriate evaluation of successful implementation CCP5.4.2
frameworks for of diverse adaptation measures.
Across mountain areas, integrated monitoring of key environmental and
monitoring and socio-economic variables, including international efforts for the acquisition
and sharing of data, offers prospects for supporting the tracking of impacts
evaluation · and adaptation responses, including community-based monitoring initiatives
(Shahgedanova et al., 2021; Thornton et al., 2021).
Feasibility and · The feasibility of adaptation options for managing risks, for example those CCP5.2.2.2;
CCP5.4.2;
suitability of that could facilitate systems transitions with respect to energy, remains CCP5.4.3
adaptation largely unexplored in the literature, with limited evidence on how projected
options for climate change could impact prospects to develop wind, solar or biomass
managing energy production and use in mountain contexts.
climate risks · Given assessments on observed adaptation (Section CCP5.2) and adaptation
responses (Section CCP5.4), few studies report a `systems approach' to the
study and evaluation of adaptations that combine all relevant aspects of the
risk framework (i.e. hazards, exposure, and vulnerabilities), including how
synergies and trade-offs are considered in context for managing risks.
· There is limited evidence of the feasibility and long-term effectiveness of
adaptation measures to address climate-related impacts and related losses and
damages in cities and settlements experiencing changing demographics.
1
2
3 [START FAQ CCP5.1 HERE]
4
5 FAQ CCP5.1: How is freshwater from mountain regions affected by climate change, and what are the
6 consequences for people and ecosystems?
7
8 Sources of freshwater from mountains such as rainfall, snow and glacier melt, and groundwater are all
9 strongly affected by climate change, leading to important changes in water supply in terms of quantity, and
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1 partly quality, and timing (e.g. shifts and changes in seasonality). In many cases, the effects on ecosystems
2 and people are negative, e.g. creating or exacerbating ecosystem degradation, water scarcity, or competition
3 or conflict over water.
4
5 River flow is a main source of freshwater both in mountain regions and downstream areas. Various sources
6 contribute to it, including rainfall, snow and glacier melt, and groundwater. Climate change affects these
7 different sources in different ways. Climate change affects rainfall patterns such as long-term increase or
8 decrease, seasonal shifts or changes in rainfall intensity. Rising temperatures strongly influence snow and
9 glacier melt generated river discharge; the snowmelt season starts earlier, less snow mass is available for
10 melt, and snowmelt contribution to river flow thus decreases over the year. Whether rising temperatures
11 produce meltwater from glaciers depends on the state and characteristics of the glaciers and the catchment
12 basin. The concept of `peak water' implies that first, as glaciers shrink in response to a warmer climate, more
13 meltwater is released until a turning point (peak water) after which glaciers melt and thus its contribution to
14 river flow decreases. In many mountain regions worldwide, glaciers and their basins have already passed
15 peak water, and the runoff contribution of glaciers is on the decline. Glacier shrinkage not only influences
16 river discharge but also water quality. In the Andes of Peru, for instance, it has been observed that retreating
17 glaciers expose bedrock, resulting in more acid water because of minerals that dissolve from the rock.
18 Mountain ecosystems are also affected by changing freshwater availability. For instance, high-elevation
19 wetlands in the tropical Andes critically depend on glacier meltwater during the dry season and the
20 disappearance of this freshwater source results in ecosystem degradation.
21
22 The effect of climate change on groundwater in mountains is insufficiently understood. Infiltrating water
23 from glaciers and snowmelt plays an important role in groundwater recharge. Groundwater recharge is
24 expected to decrease with continued climate change in several mountain regions. In the Himalaya many
25 springs have already been observed to decline.
26
27 The availability of freshwater is a function of water supply and water demand, with the latter being
28 determined by sectors such as agriculture, energy, industry, or domestic use, as well as by competition
29 between these sectors. Formal and informal water extraction and use prevail, and competition includes issues
30 of inequalities, and power relations and asymmetry. Consequently, the effects of climate change on water
31 resources, people and ecosystems are strongly modulated and often exacerbated by socio-economic
32 development and related water resource management. For example, increasing frequency and intensity of
33 droughts in the European Alps, combined with decline and seasonal shifts of river runoff from snow and
34 glacier melt, is expected to result in growing competition between different sectors, such as hydropower,
35 agriculture, and tourism. Similar developments are projected or have already been observed in many other
36 mountain regions. This situation calls for strengthening and improving negotiation formats for water
37 management that are transparent, equal, and socially and environmentally just. Management of water
38 demand and strategies that entail multiple uses of water will become increasingly important in this context.
39
40 [END FAQ CCP5.1 HERE]
41
42
43 [START FAQ CCP5.2 HERE]
44
45 FAQ CCP5.2: Are people in mountain regions, and further downstream, facing more severe risks to
46 water-related disasters due to climate change, and how are they coping?
47
48 Mountain regions have always been affected by either too much or too little water. Because of climate
49 change, hazards are changing rapidly and becoming even more unpredictable. Whether or not these changes
50 will result in more disasters locally and further downstream depends on several factors, not least the fact
51 that more people are settling in exposed locations. People in mountains have a history of developing skills to
52 live in a dangerous and dynamic environment, which will be invaluable in the future when combined with
53 inclusive and long-term disaster risk reduction measures.
54
55 Water-related hazards in mountains include rainfall (pluvial) and river (fluvial) floods, extreme rainfall-
56 induced landslides, debris flows, ice and snow avalanches and droughts. When people are exposed and
57 vulnerable to these hazards, there is potential for them to result in disasters. Floods and landslides in
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1 mountains contribute to, and count amongst the most devastating disasters globally, often resulting in
2 significant losses such as high numbers of fatalities and damages. Climate change may change rainfall
3 frequency/intensity distributions, potentially leading to floods and droughts. Climate change may also lead to
4 shifts in precipitation type, with more precipitation falling as rain than snow in the future., which further
5 impacts both short- and long-term water storage, and therefore impacts downstream ecosystems and cities.
6
7 Although climate change directly affects water-related hazards, studies indicate that above and beyond
8 natural hazards, disaster risk and disasters are influenced to a major extent by vulnerability and exposure.
9 This is of relevance in mountains, where disaster risk is influenced by population growth, induced
10 displacements, land-use changes and inefficient water distribution systems. For example, current trends
11 suggest that more people are settling in exposed locations, with more infrastructure being built and activities
12 such as tourism and recreation being promoted, exacerbating this exposure.
13
14 Experiences in dealing with water-related disasters provide a basis from which to build adequate responses
15 to increasing risks in the future. For example, upgrading infrastructure such as dams and embankments can
16 help address water shortages, but diversification of income-generating activities, such as subsistence farming
17 moving away from certain drought-sensitive crops, can also help.
18
19 The risk perceptions of people also shape their behaviours in coping with disaster risks. For example, based
20 on their longstanding observations and local knowledge, communities in the southern part of the Peruvian
21 Andes identified the shrinking of glaciers, more frequent and intense extreme weather events, more extreme
22 temperatures, and shortened rainy seasons as key challenges. The recognition of local knowledge is key to
23 address these challenges, as well as provide a basis for the transformation of current systems. A lack of
24 community involvement and participation in decision making on how to addresses disaster risk can
25 contribute to a mismatch between perceptions and behaviours towards those risks, and the actions needed to
26 reduce losses. Therefore, measures which are flexible, address the objectives and needs of all those affected
27 by disasters and bring long term benefits have more chances of being successful in dealing with future
28 disaster risks.
29
30 [END FAQ CCP5.2 HERE]
31
32
33 [START FAQ CCP5.3 HERE]
34
35 FAQ CCP5.3: Is climate change a risk to mountain species and ecosystems, and will this affect people?
36
37 Treeline position, bioclimatic zones and species ranges move up in elevation as the climate warms,
38 increasing the risk of extinction for species isolated on mountaintops as a result of exceeding their
39 physiological limits, loss of habitat or competition from colonising species. Additionally, climate change may
40 alter the quality and quantity of food and natural products on which the livelihood of many mountain
41 communities depends.
42
43 Mountain regions cover about a quarter of the Earth's land surface, scattered around the globe and may
44 support a wide range of climates within short horizontal distances. Mountains have experienced above-
45 average warming, and this trend is expected to continue. Mountains provide a variety of goods for people,
46 are home to many Indigenous Peoples and are attractive for tourism and recreational activities. Mountain
47 regions support many different ecosystems and some are very species rich. Mountain regions can be vast and
48 diverse, and climate change and impacts on ecosystems vary greatly depending on location.
49
50 With increasing average global temperature, the climatic conditions under which plants and animals can
51 thrive are shifting to higher elevations. Movement of some plant taxa toward mountaintops, has been
52 observed in the past decades. However, for species restricted to the highest elevations, there is nowhere to
53 move to, meaning they are increasingly at risk of extinction. Climatic conditions may exceed the
54 physiological limits for species and the habitat may become unsuitable for others. There is also a risk from
55 competition with colonizing native species and invading non-native species, spreading to higher elevations
56 and some species cannot move quickly enough to keep pace with the change in climate. The most vulnerable
57 species are those that reproduce and disperse slowly and those that are isolated on the mountaintops,
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1 including endemic species, which may face global extinction. In other cases species will be lost from some
2 parts of their current range. Mountains can however allow other species to survive in areas where they would
3 not otherwise do so, because of small scale variations in climate with elevation or different aspects of slopes.
4
5 Changes in snow cover and snow duration are related to changes in temperature and precipitation and are
6 also critical for plants and animals. In particular, glacier retreat and changing snow patterns affect both
7 streamflow dynamics (including extremes) and soil moisture conditions and can cause moisture shortages
8 during the growing season. Change of snow patterns can critically affect animal movements in mountains.
9 Other processes creating stresses on mountain ecosystems are direct human impacts, such as the influence of
10 grazing, tourism, air pollution and nitrogen deposition on alpine vegetation. In some cases, these impacts can
11 be so large on the goods and services provided by alpine ecosystems, that they can overshadow the effects of
12 climate change or exacerbate its effects.
13
14 In many mountain regions, multiple sources of evidence point to tree expansions into treeless area above
15 (and in some cases below) the forest belt. This may increase forest productivity at the upper treeline.
16 Treelines have moved up in the last 30-100 years in many mountain regions, including e.g. Andes, Urals and
17 Altai. At the same time, since the 1990s, treelines responses in different parts of the Himalaya have been
18 highly variable, in some places advancing upslope, in others demonstrating little change, and in others
19 moving downward. This can be explained by site-specific complex interactions of the positive effect of
20 warming on tree growth, drought stress, change in snow precipitation, land-use change, especially grazing,
21 and other factors. Treelines are affected by land use and management around the globe and changing land-
22 use practices can supersede climate change effects in some mountain regions. An upward shift in elevation
23 of bioclimatic zones, decreases in area of the highest elevation zones, and an expansion of the lower zones
24 can be expected by mid-century, for examples in regions such as the Himalaya.
25
26 In some regions, the livelihoods of many local mountain communities depend on access to firewood,
27 pastures, edible plants and mushrooms, medicinal and aromatic plants. Climate change can alter the quality
28 and quantity of these ecosystem services; however, the degree and direction of change are context specific.
29 The appeal and feasibility of mountains for tourism and recreation activities are also affected by climate
30 change.
31
32 [END FAQ CCP5.3 HERE]
33
34
35 [START FAQ CCP5.4 HERE]
36
37 FAQ CCP5.4: What type of adaptation options are feasible to address the impacts of climate change in
38 mountain regions under different levels of warming, and what are their limits?
39
40 The feasibility of adaptation to address risks in mountain regions is influenced by numerous factors, many of
41 which are unique to mountain people and their environment. Adaptation efforts in mountains are mainly
42 made of small steps and largely autonomous. Robust and flexible adaptation measures have a better chance
43 to address risks, but eventually large systemic transformation will be needed for higher levels of warming.
44 Empirical evidence on "what works and what does not work" is largely absent, but urgently needed.
45
46 The term feasibility refers to climate goals and adaptation options that are possible and desirable. Feasibility
47 is influenced by factors such as economic viability, availability of technical resources, institutional support,
48 social capital, ecological and adaptive capacity, and biophysical conditions. Establishing the feasibility of
49 options under changing climatic and socio-economic conditions is not an easy task mostly because even
50 present feasibility is difficult to assess in mountains, due to a lack of systematic information on opportunities
51 and challenges of adaptation in practice.
52
53 Underlying environmental conditions such as limited space, shallow soils, exposure to numerous hazards,
54 climate-sensitive ecosystems and isolation make it particularly difficult to implement adaptation at scales
55 relevant for implementation. Common adaptation options are often implemented at the individual, household
56 or community scale. These options are incremental and have generated observable results and outcomes.
57 Adaptation actions that involve partial changes that do not dramatically alter established practices and
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1 behaviours seem to have better chances of being implemented than systemic or structural changes. Formal or
2 planned adaptation efforts which are more institutionally driven are only a small proportion of observed
3 adaptation in mountains regions. Where adaptation options are implemented, they are often not only
4 targeting climate change, but an array of other issues, priorities, and pressures experienced by and in those
5 communities (e.g. livelihood diversification in farming practices).
6
7 Whether or not adaptation options are feasible does not say much about their effectiveness, i.e. the degree to
8 which adaptation has been or will be successful in reducing the risks of negative impacts. Adaptation is
9 difficult to disentangle from other factors that contribute to both increasing and decreasing risks. Since
10 adaptation in mountains is often autonomous and unplanned, measuring its effectiveness is complex and
11 missed by more conventional, formal, or structured monitoring and evaluation frameworks.
12
13 Evidence suggests that promising measures being taken in mountains are those that are robust under
14 uncertain futures, allow for adaptive planning and management, and respond to multiple interests and
15 purposes. For example, multi-purpose water reservoirs can alleviate multiple stressors and address several
16 risks such as those from natural hazards and water shortages. Capacity building and awareness-raising can go
17 a long way to ensure that these measures are also socially acceptable if combined with more structural and
18 systemic changes. Indeed, transformations are happening slowly in mountains and it is unlikely that small
19 steps and incremental measures will be able to cope with more severe and pervasive risks.
20
21 Overall, empirical evidence on the effectiveness of adaptation to reducing risk is largely missing but is
22 urgently needed to better understand what works and what does not work under certain circumstances.
23
24 [END FAQ CCP5.4 HERE]
25
26
27 [START FAQ CCP5.5 HERE]
28
29 FAQ CCP5.5: Why regional cooperation and transboundary governance is needed for sustainable
30 mountain development?
31
32 Regional cooperation and transboundary governance are key to managing our vast mountain resources
33 because they do not necessarily share political boundaries. Mountain countries need to come together, share
34 data and information, form joint management committees, bring in policies and take decisions that benefit
35 all countries equitably. Lack of cooperation may lead to missing important opportunities to address climate
36 risks and adequately manage mountain resources, which can cause potential social unrest and spark conflict
37 within and between countries.
38
39 Mountains are climate change hotspots that are highly susceptible to climate change. Due to rapidly
40 changing climatic conditions, climate change is one of the major issues that would benefit from regional
41 cooperation. The transboundary management of mountains means shared legal and institutional frameworks
42 for sharing the benefits and costs of managing the mountain ranges across boundaries, be it local or district
43 jurisdictions within countries or indeed across national boundaries.
44
45 The IPCC's Special Report on Oceans and Cryosphere refers to governance as an "effort to establish,
46 reaffirm or change formal and informal institutions at all scales to negotiate relationships, resolve social
47 conflicts and realise mutual gains". Governance is an act of governments, NGOs, private sectors, and civil
48 society in establishing rules and norms for restricting the use of common goods. "Institutions can guide,
49 constrain, and shape human interaction through direct control, incentives, and processes of socialisation".
50 How do we apply the definitions of governance and institutions in the context of mountains? Since
51 governance not only refers to government, which is a formal arm of the state, it also talks about other
52 agencies such as community organizations, non-profit or businesses that play a vital role in society and
53 influences individual or collective decisions and help in preventing the overexploitation of its resources.
54
55 To comprehend the processes of governance in mountain areas, we need to recognize how each of these
56 agencies add to the enduring task of enabling and managing change at the system level but also to preserving
57 social structure and reconciling disputes. For the sustainable and resilient development of mountain regions,
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FINAL DRAFT Cross-Chapter Paper 5 IPCC WGII Sixth Assessment Report
1 governance mechanisms may be different than those applied for managing other resources such as coastal
2 zones or rivers. This is also because mountains are mostly transboundary and do not necessarily follow
3 political boundaries. Mountain governance, therefore, is about managing the resources across political
4 boundaries for the benefit of all countries. This includes downstream countries that also rely on these
5 resources such as water, silt, and other resources from these mountain regions. These include high
6 rangelands, biodiversity hotspots, forests, glaciers etc.
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8 There are several examples of regional cooperation around the governance of shared resources in mountains.
9 Some examples come from the Arctic (bottom-up and science-based evolution of Arctic cooperation), South-
10 East Europe (regionalisation of environmental benefits) and the Hindu Kush Himalaya region (inter-
11 governmental scientific institution for research and data sharing). Mountains share resources and therefore,
12 their management will benefit from cooperation between countries. Transboundary cooperation is not only
13 needed to address transboundary climate risks and regional adaptation to climate change in mountains, but
14 also to work across countries to reduce greenhouse gas emissions.
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16 [END FAQ CCP5.5 HERE]
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