Editing IPCC:AR6/SROCC/Chapter-2 (section)

== Box 2.4 Challenges to Farmers and Local Population Related to Shrinkages in the Cryosphere: Cordillera Blanca, Peru ==

<div id="section-2-3-2-3disaster-risk-reduction-and-adaptation-block-1"></div>

The Cordillera Blanca of Peru contains most of the glaciers in the tropics, and its glacier coverage declined significantly in the recent past (Burns and Nolin, 2014 <sup>[[#fn:r652|652]]</sup> ; Mark et al., 2017 <sup>[[#fn:r653|653]]</sup> ). Since the 1940s, glacier hazards have killed thousands (Carey, 2005 <sup>[[#fn:r654|654]]</sup> ) and remain threatening. Glacier wastage has also reduced river runoff in most of its basins in recent decades, particularly in the dry season (Baraer et al., 2012 <sup>[[#fn:r655|655]]</sup> ; Vuille et al., 2018 <sup>[[#fn:r656|656]]</sup> ). Residents living adjacent to the Cordillera Blanca have long recognised this glacier shrinkage, including rural populations living near glaciers and urban residents worried about glacier lake floods and glacier landslides (Jurt et al., 2015 <sup>[[#fn:r657|657]]</sup> ; Walter, 2017 <sup>[[#fn:r658|658]]</sup> ). Glacier hazards and the glacier runoff variability increase exposure and uncertainty while diminishing adaptive capacity (Rasmussen, 2016 <sup>[[#fn:r659|659]]</sup> ).

Cordillera Blanca residents’ risk of glacier-related disasters is amplified by intersecting physical and societal factors. Cryosphere hazards include expanding or newly forming glacial lakes, slope instability, and other consequences of rising temperatures, and precipitation changes (Emmer et al., 2016 <sup>[[#fn:r660|660]]</sup> ; Colonia et al., 2017 <sup>[[#fn:r661|661]]</sup> ; Haeberli et al., 2017 <sup>[[#fn:r662|662]]</sup> ). Human vulnerability to these hazards is conditioned by factors such as poverty, limited political influence and resources, minimal access to education and healthcare, and weak government institutions (Hegglin and Huggel, 2008 <sup>[[#fn:r663|663]]</sup> ; Carey et al., 2012 <sup>[[#fn:r664|664]]</sup> ; Lynch, 2012 <sup>[[#fn:r665|665]]</sup> ; Carey et al., 2014 <sup>[[#fn:r666|666]]</sup> ; Heikkinen, 2017 <sup>[[#fn:r667|667]]</sup> ). Early warning systems have been, or are being, installed at glacial lakes Laguna 513 and Palcacocha to protect populations (Muñoz et al., 2016 <sup>[[#fn:r668|668]]</sup> ). Laguna 513 was lowered by 20 m for outburst prevention in the early 1990s but nonetheless caused a destructive flood in 2010, though much smaller and less destructive than a flood that would have been expected without previous lake mitigation works (Carey et al., 2012 <sup>[[#fn:r669|669]]</sup> ; Schneider et al., 2014 <sup>[[#fn:r670|670]]</sup> ). An early warning system was subsequently installed, but some local residents destroyed it in 2017 due to political, social and cultural conflicts (Fraser, 2017 <sup>[[#fn:r671|671]]</sup> ). The nearby Lake Palcacocha also threatens populations (Wegner, 2014 <sup>[[#fn:r672|672]]</sup> ; Somos-Valenzuela et al., 2016 <sup>[[#fn:r673|673]]</sup> ). The usefulness for ground-level education and communication regarding advanced early warning systems has been demonstrated in Peru (Muñoz et al., 2016 <sup>[[#fn:r674|674]]</sup> ).

Vulnerability to hydrologic variability and declining glacier runoff is also shaped by intertwining human and biophysical drivers playing out in dynamic hydro-social systems (Bury et al., 2013 <sup>[[#fn:r675|675]]</sup> ; Rasmussen 2016 <sup>[[#fn:r676|676]]</sup> ; Drenkhan et al., 2015 <sup>[[#fn:r677|677]]</sup> ; Carey et al., 2017 <sup>[[#fn:r678|678]]</sup> ). Water security is influenced by both water availability (supply from glaciers) as well as by water distribution, which is affected by factors such as water laws and policies, global demand for agricultural products grown in the lower Santa River basin, energy demands and hydroelectricity production, potable water usage, and livelihood transformations over time (Carey et al., 2014 <sup>[[#fn:r679|679]]</sup> ; Vuille et al., 2018 <sup>[[#fn:r680|680]]</sup> ). In some cases, the formation of new glacial lakes can create opportunities as well as hazards, such as new tourist attractions and reservoirs of water, thereby showing how socioeconomic and geophysical forces intersect in complex ways (Colonia et al., 2017 <sup>[[#fn:r681|681]]</sup> ).

<div id="section-2-3-2-3disaster-risk-reduction-and-adaptation-block-3"></div>

<span id="figure-2.8"></span>
<!-- START IMG -->
<!-- IMG TITLE -->
'''Figure 2.8'''

<span id="figure-2.8-synthesis-of-observed-physical-changes-and-impacts-on-ecosystems-and-human-systems-and-ecosystems-services-in-eleven-high-mountain-regions-over-past-decades-that-can-at-least-partly-be-attributed-to-changes-in-the-cryosphere.-only-observations-documented-in-the-scientific-literature-are-shown-but-impacts-may-also-be-experienced-elsewhere.-for"></span>
<!-- IMG CAPTION -->
'''Figure 2.8 | Synthesis of observed physical changes and impacts on ecosystems and human systems and ecosystems services in eleven high mountain regions over past decades that can at least partly be attributed to changes in the cryosphere. Only observations documented in the scientific literature are shown, but impacts may also be experienced elsewhere. For […]'''
<!-- IMG FILE -->
[[File:4a23d20c04f16d9b33af52aace323e60 IPCC-SROCC-CH_2_8.jpg]]

Figure 2.8 | Synthesis of observed physical changes and impacts on ecosystems and human systems and ecosystems services in eleven high mountain regions over past decades that can at least partly be attributed to changes in the cryosphere. Only observations documented in the scientific literature are shown, but impacts may also be experienced elsewhere. For physical changes yellow/green refers to an increase/decrease, respectively, in amount or frequency of the measured variable. For impacts on ecosystems and human systems and ecosystems services blue or red depicts whether an observed impact is positive (beneficial) or negative (adverse). Cells assigned ‘increase and decrease’ indicate that within that region both increase and decrease of physical changes are found, but are not necessarily equal; the same holds for cells showing ‘positive and negative’ impacts. Confidence levels refer to confidence in attribution to cryospheric changes. No assessment means: not applicable, not assessed at regional scale, or the evidence is insufficient for assessment. Tundra refers to tundra and alpine meadows. Migration refers to an increase and decrease in net migration, not beneficial/adverse value. Impacts on tourism refer to the operating conditions for the tourism sector. Cultural services include cultural identity, sense of home, intrinsic and aesthetic values, as well as contributions from glacier archaeology. Figure is based on observed impacts listed in Table SM2.11.

<!-- END IMG -->
<span id="ecosystems">
</span>
=== 2.3.3 Ecosystems ===

<div id="section-2-3-3ecosystems-block-1"></div>

Widespread climate driven ecological changes have occurred in high mountain ecosystems over the past century. Those impacts were assessed in a dedicated manner only in earlier IPCC assessments ( Beniston and Fox, 1996 <sup>[[#fn:r682|682]]</sup> ; Gitay et al., 2001 <sup>[[#fn:r683|683]]</sup> ; Fischlin et al., 2007 <sup>[[#fn:r684|684]]</sup> ) but not in AR5 ( Settele et al., 2014 <sup>[[#fn:r685|685]]</sup> ). Two of the most evident changes include range shifts of plants and animals in Central Europe and the Himalaya but also for other mountain regions (e.g., Morueta-Holme et al., 2015; Evangelista et al., 2016 <sup>[[#fn:r686|686]]</sup> ; Freeman et al., 2018 <sup>[[#fn:r687|687]]</sup> ; Liang et al., 2018 <sup>[[#fn:r688|688]]</sup> ; You et al., 2018 <sup>[[#fn:r689|689]]</sup> ; He et al., 2019 <sup>[[#fn:r690|690]]</sup> ), and increases in species richness on mountain summits ( Khamis et al., 2016 <sup>[[#fn:r691|691]]</sup> ; Fell et al., 2017 <sup>[[#fn:r692|692]]</sup> ; Steinbauer et al., 2018 <sup>[[#fn:r693|693]]</sup> ) of which some have accelerated during recent decades (e.g., Steinbauer et al., 2018), though slowing over the past ten years in Austria (e.g., Lamprecht et al., 2018). While many c hanges in freshwater communities have been directly attributed to changes in the cryosphere (Jacobsen et al., 2012 <sup>[[#fn:r694|694]]</sup> ; Milner et al., 2017 <sup>[[#fn:r695|695]]</sup> ), separating the direct influence of atmospheric warming from the influence of concomitant cryospheric change and independent biotic processes has been often challenging for t errestrial ecosystems (Grytnes et al., 2014 <sup>[[#fn:r696|696]]</sup> ; Lesica and Crone, 2016 <sup>[[#fn:r697|697]]</sup> ; Frei et al., 2018 <sup>[[#fn:r698|698]]</sup> ; Lamprecht et al., 2018 <sup>[[#fn:r699|699]]</sup> ). Changing climate in high mountains places further stress on biota, which are already impacted by land use and its change, direct exploitation, and pollutants (Díaz et al., 2019 <sup>[[#fn:r700|700]]</sup> ; Wester et al., 2019 <sup>[[#fn:r701|701]]</sup> ). Species are required to shift their behaviours, including seasonal aspects, and distributional ranges to track suitable climate conditions (Settele et al., 2014 <sup>[[#fn:r702|702]]</sup> ). In the Special Report on Global Warming of 1.5°C (SR15), climate change scenarios exceeding mean global warming of 1.5° C relative to preindustrial levels have been estimated to lead to major impacts on species abundances, community structure, and ecosystem functioning in high mountain areas (Hoegh-Guldberg et al., 2018 <sup>[[#fn:r703|703]]</sup> ). The size and isolation of mountain habitats (Steinbauer et al., 2016 <sup>[[#fn:r704|704]]</sup> ; Cotto et al., 2017 <sup>[[#fn:r705|705]]</sup> ), which may vary strongly with the topography of mountain ridges (Elsen and Tingley, 2015 <sup>[[#fn:r706|706]]</sup> ; Graae et al., 2018 <sup>[[#fn:r707|707]]</sup> ), affects critically the survival of species as they migrate across mountain ranges, increasing in general the risks for many species from climate change (Settele et al., 2014 <sup>[[#fn:r708|708]]</sup> ; Dobrowski and Parks, 2016 <sup>[[#fn:r709|709]]</sup> ) .

<div id="section-2-3-3-1-terrestrial-biota"></div>

<span id="terrestrial-biota"></span>
==== 2.3.3.1 Terrestrial Biota ====

<div id="section-2-3-3-1-terrestrial-biota-block-1"></div>

The cryosphere can play a critical role in moderating and driving how species respond to climate change in high mountains ( ''high confidence'' ). Many mountain plant and animal species have changed abundances and migrated upslope while expanding or contracting their ranges over the past decades to century, whereas others show no change ( Morueta-Holme et al., 2015 <sup>[[#fn:r710|710]]</sup> ; Suding et al., 2015 <sup>[[#fn:r711|711]]</sup> ; Lesica and Crone, 2016 <sup>[[#fn:r712|712]]</sup> ; Fadrique et al., 2018 <sup>[[#fn:r713|713]]</sup> ; Freeman et al., 2018 <sup>[[#fn:r714|714]]</sup> ; Rumpf et al., 2018 <sup>[[#fn:r715|715]]</sup> ; Johnston et al., 2019 <sup>[[#fn:r716|716]]</sup> ; Rumpf et al., 2019 <sup>[[#fn:r717|717]]</sup> ) ( ''medium agreement'' , ''robust evidence'' ). These responses are often linked directly to warming, yet a changing cryosphere, for example, in the form of decreasing snow thickness or altered seasonality of snow (e.g., Matteodo et al., 2016; Kirkpatrick et al., 2017 <sup>[[#fn:r718|718]]</sup> ; Amagai et al., 2018 <sup>[[#fn:r719|719]]</sup> ; Wu et al., 2018 <sup>[[#fn:r720|720]]</sup> ) or indirectly leading to changes in soil moisture ( Harpold and Molotch, 2015 <sup>[[#fn:r721|721]]</sup> ), can play a significant role for growth, fitness and survival of many species (e.g., Grytnes et al., 2014; Winkler et al., 2016 <sup>[[#fn:r722|722]]</sup> ) ( ''medium evidence, high agreement'' ).

Cryospheric changes were found to be beneficial for some plant species and for ecosystems in some regions, improving a number of ecosystem services, such as by provisioning new habitat for endemic plant species and increasing plant productivity ( ''high confidence'' ). Decreasing snow cover duration, glacier retreat and permafrost thaw have already and will over coming decades allow plant species, including some endemic species, to increase their abundance and extend their range in many mountain ranges (Yang et al., 2010a <sup>[[#fn:r723|723]]</sup> ; Grytnes et al., 2014 <sup>[[#fn:r724|724]]</sup> ; Elsen and Tingley, 2015 <sup>[[#fn:r725|725]]</sup> ; Dolezal et al., 2016 <sup>[[#fn:r726|726]]</sup> ; Wang et al., 2016b <sup>[[#fn:r727|727]]</sup> ; D’Amico et al., 2017 <sup>[[#fn:r728|728]]</sup> ; Liang et al., 2018 <sup>[[#fn:r729|729]]</sup> ; Yang et al., 2018 <sup>[[#fn:r730|730]]</sup> ; You et al., 2018 <sup>[[#fn:r731|731]]</sup> ; He et al., 2019 <sup>[[#fn:r732|732]]</sup> ). Over recent decades, plant colonisation after glacier retreat has been swift, for example, at many sites with favourable soils in the European Alps (Matthews and Vater, 2015 <sup>[[#fn:r733|733]]</sup> ; Fickert and Grüninger, 2018 <sup>[[#fn:r734|734]]</sup> ) or has even accelerated compared to 100 years ago (Fickert et al., 2016 <sup>[[#fn:r735|735]]</sup> ). At other sites of the European Alps (D’Amico et al., 2017) and in other mountain ranges (e.g., Andes and Alaska; Darcy et al., 2018 <sup>[[#fn:r736|736]]</sup> ; Zimmer et al., 2018 <sup>[[#fn:r737|737]]</sup> ) the rate of colonisation remains slow due to soil type, soil formation and phosphorous limitation (Darcy et al., 2018 <sup>[[#fn:r738|738]]</sup> ). In Bhutan, snowlines have ascended and new plant species have established themselves in these areas, yet despite range expansion and increased productivity, yak herders describe impacts on the ecosystem services as mostly negative (Wangchuk and Wangdi, 2018 <sup>[[#fn:r739|739]]</sup> ). Earlier snowmelt often leads to earlier plant growth and, provided there is sufficient water, including from underlying permafrost, plant productivity has increased in many alpine regions (e.g., Williams et al., 2015; Yang et al., 2018 <sup>[[#fn:r740|740]]</sup> ). Decreased snow cover duration has led to colonisation of snowbed communities by wide-ranging species in several regions, for example, in the Australian Alps (Pickering et al., 2014 <sup>[[#fn:r741|741]]</sup> ), though this can lead to declines in the abundance of resident species, for example, in the Swiss Alps (Matteodo et al., 2016 <sup>[[#fn:r742|742]]</sup> ).

Cryospheric change in high mountains directly harms some plant species and ecosystems in some regions, degrading a number of ecosystem services, such as maintaining regional and global biodiversity, and some provisioning services, for example, fodder or wood production, in terms of timing and magnitude ( ''high confidence'' ). In mountains, microrefugia (a local environment different from surrounding areas) and isolation have contributed to high plant endemism that increases with elevation (Steinbauer et al., 2016 <sup>[[#fn:r743|743]]</sup> ; Zhang and Zhang, 2017 <sup>[[#fn:r744|744]]</sup> ; Muellner-Riehl, 2019 <sup>[[#fn:r745|745]]</sup> ). Microrefugia may enable alpine species to persist if global warming remains below 2˚C relative pre-industrial levels (Scherrer and Körner, 2011 <sup>[[#fn:r746|746]]</sup> ; Hannah et al., 2014 <sup>[[#fn:r747|747]]</sup> ; Graae et al., 2018 <sup>[[#fn:r748|748]]</sup> ) ( ''medium evidence'' , ''medium agreement'' ). Yet, where glaciers have been retreating over recent decades, cool microrefugia have shifted location or decreased in extent ( Gentili et al., 2015 <sup>[[#fn:r749|749]]</sup> ). In regions with insufficient summer precipitation, earlier snowmelt and absence of permafrost lead to insufficient water supply during the growing season, and consequently an earlier end of peak season, altered species composition, and a decline in greenness or productivity ( Trujillo et al., 2012 <sup>[[#fn:r750|750]]</sup> ; Sloat et al., 2015 <sup>[[#fn:r751|751]]</sup> ; Williams et al., 2015 <sup>[[#fn:r752|752]]</sup> ; Yang et al., 2018 <sup>[[#fn:r753|753]]</sup> ) ( ''medium evidence'' , ''high agreement'' ). Across elevations, alpine-restricted species show greater sensitivity to the timing of snowmelt than wide ranging species ( Lesica, 2014 <sup>[[#fn:r754|754]]</sup> ; Winkler et al., 2018 <sup>[[#fn:r755|755]]</sup> ), and though the cause is often not known, some alpine-restricted species have declined in abundance or disappeared in regions with distinctive flora ( Evangelista et al., 2016 <sup>[[#fn:r756|756]]</sup> ; Giménez-Benavides et al., 2018 <sup>[[#fn:r757|757]]</sup> ; Lamprecht et al., 2018 <sup>[[#fn:r758|758]]</sup> ; Panetta et al., 2018 <sup>[[#fn:r759|759]]</sup> ) ( ''medium evidence, high agreement'' ).

The shrinking cryosphere represents a loss of critical habitat for wildlife that depend on snow and ice cover, affecting well-known and unique high-elevation species ( ''high confidence'' ). Areas with seasonal snow and glaciers are essential habitat for birds and mammals within mountain ecosystems for foraging, relief from climate stress, food caching and nesting grounds ( Hall et al., 2016 <sup>[[#fn:r760|760]]</sup> ; Rosvold, 2016 <sup>[[#fn:r761|761]]</sup> ) ( ''robust evidence'' ). Above 5,000 m a.s.l. in Peru, there was recently a first observation of bird nesting for which its nesting may be glacier obligate ( Hardy et al., 2018 <sup>[[#fn:r762|762]]</sup> ). The insulated and thermally stable region under the snow at the soil-snow interface, termed the subnivean, has been affected by changing snowpack, limiting winter activity and decreasing population growth for some mountain animals, including frogs, rodents and small carnivores (Penczykowski et al., 2017 <sup>[[#fn:r763|763]]</sup> ; Zuckerberg and Pauli, 2018 <sup>[[#fn:r764|764]]</sup> ; Kissel et al., 2019 <sup>[[#fn:r765|765]]</sup> ) ( ''medium evidence'' ). Many mountain animals have been observed to change their behaviour in a subtle manner, for example., in foraging or hunting behaviour, due to cryospheric changes (e.g., Rosvold, 2016; Büntgen et al., 2017 <sup>[[#fn:r766|766]]</sup> ; Mahoney et al., 2018 <sup>[[#fn:r767|767]]</sup> ) ( ''medium evidence'' , ''high agreement'' ). In the Canadian Rocky Mountains, grizzly bears have moved to new snow free habitat after emerging in spring from hibernation to dig for forage, which may increase the risk of human-bear encounters (Berman et al., 2019 <sup>[[#fn:r768|768]]</sup> ). In the US Central Rocky Mountains, migratory herbivores, such as elk, moose and bison, track newly emergent vegetation that greens soon after snowmelt (Merkle et al., 2016 <sup>[[#fn:r769|769]]</sup> ). For elk, this was found to increase fat gain (Middleton et al., 2018 <sup>[[#fn:r770|770]]</sup> ). Due to loss of snow patches that increase surface water and thus insect abundance, some mammal species, for example, reindeer and ibex, have changed their foraging behaviour to evade the biting insects with negative impacts on reproductive fitness (Vors and Boyce, 2009 <sup>[[#fn:r771|771]]</sup> ; Büntgen et al., 2017 <sup>[[#fn:r772|772]]</sup> ).

Many endemic plant and animal species including mammals and invertebrates in high mountain regions are vulnerable to further decreasing snow cover duration, such as later onset of snow accumulation and/or earlier snowmelt ( ''high confidence'' ) ( Williams et al., 2015 <sup>[[#fn:r773|773]]</sup> ; Slatyer et al., 2017 <sup>[[#fn:r774|774]]</sup> ). Winter-white animals for which coat or plumage colour is cued by day length will confront more days with brown snowless ground (Zimova et al., 2018 <sup>[[#fn:r775|775]]</sup> ), which has already contributed to range contractions for several species, including hares and ptarmigan (Imperio et al., 2013 <sup>[[#fn:r776|776]]</sup> ; Sultaire et al., 2016 <sup>[[#fn:r777|777]]</sup> ; Pedersen et al., 2017 <sup>[[#fn:r778|778]]</sup> ) ( ''robust evidence'' ). Under all climate scenarios, the duration of this camouflage mismatch will increase, enhancing predation rates thereby decreasing populations of coat-colour changing species (e.g., 24% decrease by late century under RCP8.5 for snowshoe hares; Zimova et al., 2016 <sup>[[#fn:r779|779]]</sup> ; see also Atmeh et al., 2018) ( ''medium evidence'' , ''high agreement'' ). For roe deer (Plard et al., 2014 <sup>[[#fn:r780|780]]</sup> ) and mountain goats (White et al., 2017 <sup>[[#fn:r781|781]]</sup> ), climate driven changes in snowmelt duration and summer temperatures will reduce survival considerably under RCP4.5 and RCP8.5 scenarios ( ''medium'' ''evidence'' , ''high agreement'' ).

<div id="section-2-3-3-2-freshwater-biota"></div>

<span id="freshwater-biota"></span>
==== 2.3.3.2 Freshwater Biota ====

<div id="section-2-3-3-2-freshwater-biota-block-1"></div>

Biota in mountain freshwater ecosystems is affected by cryospheric change through alterations in both the quantity and timing of runoff from glaciers and snowmelt. Where melt water from glaciers decreases, river flows have become more variable, with water temperature and overall channel stability increasing and habitats becoming less complex (Giersch et al., 2017 <sup>[[#fn:r782|782]]</sup> ; Milner et al., 2017 <sup>[[#fn:r783|783]]</sup> ) ( ''medium evidence, medium agreement'' ).

Analysis of three invertebrate datasets from tropical (Ecuador), temperate (Italian Alps) and sub-Arctic (Iceland) alpine regions indicates that a number of cold-adapted species have decreased in abundance below a threshold of watershed glacier cover varying from 19 – 32%. With complete loss of the glaciers, 11–38% of the regional species will be lost (Jacobsen et al., 2012 <sup>[[#fn:r784|784]]</sup> ; Milner et al., 2017 <sup>[[#fn:r785|785]]</sup> ) ( ''medium confidence'' ). As evidenced in Europe (Pyrenees, Italian Alps) and North America (Rocky Mountains) (Brown et al., 2007 <sup>[[#fn:r786|786]]</sup> ; Giersch et al., 2015 <sup>[[#fn:r787|787]]</sup> ; Giersch et al., 2017 <sup>[[#fn:r788|788]]</sup> ; Lencioni, 2018 <sup>[[#fn:r789|789]]</sup> ) the loss of these invertebrates — many of them endemic — as glacier runoff decreases and transitions to a regime more dominated by snowmelt leading to a reduction in turnover between and within stream reaches (beta diversity) and regional (gamma) diversity ''(very high confidence'' ). Regional genetic diversity within individual riverine invertebrate species in mountain headwater areas has decreased with the loss of environmental heterogeneity (Giersch et al., 2017 <sup>[[#fn:r790|790]]</sup> ), as decreasing glacier runoff reduces the isolation of individuals permitting a greater degree of genetic intermixing (Finn et al., 2013 <sup>[[#fn:r791|791]]</sup> ; Finn et al., 2016 <sup>[[#fn:r792|792]]</sup> ; Jordan et al., 2016 <sup>[[#fn:r793|793]]</sup> ; Hotaling et al., 2018 <sup>[[#fn:r794|794]]</sup> ) ( ''medium evidence, high agreement'' ). However, local (alpha) diversity, dominated by generalist species of invertebrates and algae, has increased (Khamis et al., 2016 <sup>[[#fn:r795|795]]</sup> ; Fell et al., 2017 <sup>[[#fn:r796|796]]</sup> ; Brown et al., 2018 <sup>[[#fn:r797|797]]</sup> ) ( ''very'' ''high confidence'' ) in certain regions as species move upstream, although not in the Andes, where downstream migration has been observed (Jacobsen et al., 2014 <sup>[[#fn:r798|798]]</sup> ; Cauvy-Fraunié et al., 2016 <sup>[[#fn:r799|799]]</sup> ).

Many climate variables influence fisheries, through both direct and indirect pathways. The key variables linked to cryospheric change include: changes in air and water temperature, precipitation, nutrient levels and ice cover (Stenseth et al., 2003 <sup>[[#fn:r800|800]]</sup> ). A shrinking cryosphere has significantly affected cold mountain resident salmonids (e.g., brook trout, ''Salvelinus fontinalis'' ), causing further migration upstream in summer thereby shrinking their range (Hari et al., 2006 <sup>[[#fn:r801|801]]</sup> ; Eby et al., 2014 <sup>[[#fn:r802|802]]</sup> ; Young et al., 2018 <sup>[[#fn:r803|803]]</sup> ). Within the Yanamarey watershed of the Cordillera Blanca in Peru, fish stocks have either declined markedly or have become extinct in many streams, possibly due to seasonal reductions of fish habitat in the upper watershed resulting from glacier recession (Bury et al., 2011 <sup>[[#fn:r804|804]]</sup> ; Vuille et al., 2018 <sup>[[#fn:r805|805]]</sup> ). In contrast, glacier recession in the mountains of coastal Alaska and to a lesser extent the Pacific northwest have created a large number of new stream systems that have been, and could continue to be with further glacier retreat, colonised from the sea by salmon species that contribute to both commercial and sport fisheries (Milner et al., 2017 <sup>[[#fn:r806|806]]</sup> ; Schoen et al., 2017 <sup>[[#fn:r807|807]]</sup> ) ( ''medium confidence'' ). Changes in water temperature will vary seasonally, and a potential decreased frequency of rain-on-snow events in winter compared to rain-on-ground would increase water temperature, benefiting overwintering survival (Leach and Moore, 2014 <sup>[[#fn:r808|808]]</sup> ). Increased water temperature remaining below thermal tolerance limits for fish and occurring earlier in the year can benefit overall fish growth and increase fitness (Comola et al., 2015 <sup>[[#fn:r809|809]]</sup> ) ( ''medium evidence'' , ''medium agreement'' ).

In the future, increased primary production dominated by diatoms and golden algae will occur in streams as glacier runoff decreases, although some cold-tolerant diatom species will be lost, resulting in a decrease in regional diversity (Fell et al., 2017 <sup>[[#fn:r810|810]]</sup> ; Fell et al., 2018 <sup>[[#fn:r811|811]]</sup> ). Reduced glacier runoff is projected to improve water clarity in many mountain lakes, increasing biotic diversity and the abundance of bacterial and algal communities and thus primary production (Peter and Sommaruga, 2016 <sup>[[#fn:r812|812]]</sup> ) ( ''limited evidence'' ). Extinction of range-restricted prey species may increase as more favourable conditions facilitate the upstream movement of large bodied invertebrate predators (Khamis et al., 2015 <sup>[[#fn:r813|813]]</sup> ) ( ''medium confidence'' ). Modelling studies indicate a reduction in the range of native species, notably trout, in mountain streams, (Papadaki et al., 2016 <sup>[[#fn:r814|814]]</sup> ; Vigano et al., 2016 <sup>[[#fn:r815|815]]</sup> ; Young et al., 2018 <sup>[[#fn:r816|816]]</sup> ) ( ''medium evidence, high agreement'' ), which will potentially impact sport fisheries. In northwest North America, where salmon are important in native subsistence as well as commercial and sport fisheries, all species will potentially be affected by reductions in glacial runoff from mountain glaciers over time (Milner et al., 2017 <sup>[[#fn:r817|817]]</sup> ; Schoen et al., 2017 <sup>[[#fn:r818|818]]</sup> ), particularly in larger systems where migratory corridors to spawning grounds are reduced ( ''medium confidence'' ).

In summary, cryospheric change will alter freshwater communities with increases in local biodiversity but range shrinkage and extinctions for some species causes regional biodiversity to decrease ( ''robust evidence'' , ''medium agreement'' , i.e., ''high confidence'' ).

<div id="section-2-3-3-3-ecosystem-services-and-adaptation"></div>

<span id="ecosystem-services-and-adaptation"></span>
==== 2.3.3.3 Ecosystem Services and Adaptation ====

<div id="section-2-3-3-3-ecosystem-services-and-adaptation-block-1"></div>

The trend to a higher productivity in high mountain ecosystems due to a warmer environment and cryospheric changes, affects provisioning and regulating services ( ''high confidence'' ). Due to earlier snowmelt, the growing season has begun earlier, for example, on the Tibetan Plateau, and in the Swiss Alps (Wang et al., 2017 <sup>[[#fn:r819|819]]</sup> ; Xie et al., 2018 <sup>[[#fn:r820|820]]</sup> ), and in some regions earlier growth has been linked to greater plant production or greater net ecosystem production, possibly affecting carbon uptake (Scholz et al., 2018 <sup>[[#fn:r821|821]]</sup> ; Wang et al., 2018 <sup>[[#fn:r822|822]]</sup> ; Wu et al., 2018 <sup>[[#fn:r823|823]]</sup> ). In other areas productivity has decreased, despite a longer growing season, for example, in the US Rocky Mountains, US Sierra Nevada Mountains, Swiss Alps, and Tibetan Plateau (Arnold et al., 2014 <sup>[[#fn:r824|824]]</sup> ; Sloat et al., 2015 <sup>[[#fn:r825|825]]</sup> ; Wang et al., 2017 <sup>[[#fn:r826|826]]</sup> ; De Boeck et al., 2018 <sup>[[#fn:r827|827]]</sup> ; Knowles et al., 2018 <sup>[[#fn:r828|828]]</sup> ) ( ''robust evidence'' , ''medium agreement'' ). Changed productivity of the vegetation in turn can affect the timing, quantity and quality of water supply, a critical regulating service ecosystems play in high mountain areas (Goulden and Bales, 2014 <sup>[[#fn:r828|828]]</sup> ; Hubbard et al., 2018 <sup>[[#fn:r829|829]]</sup> ) ( ''medium confidence'' ). Permafrost degradation has dramatically changed some alpine ecosystems through altered soil temperature and permeability, decreasing the climate regulating service of a vast region and leading to lowered ground water and new and shrinking lakes on the Tibetan Plateau (Jin et al., 2009 <sup>[[#fn:r830|830]]</sup> ; Yang et al., 2010b <sup>[[#fn:r831|831]]</sup> ; Shen et al., 2018 <sup>[[#fn:r832|832]]</sup> ) ( ''medium evidence, high agreement'' ).

Ecosystems and their services are vulnerable to changes in the intensity and/or the frequency of an ecological disturbance that exceed the previous range of variation (Johnstone et al., 2016 <sup>[[#fn:r833|833]]</sup> ; Camac et al., 2017 <sup>[[#fn:r834|834]]</sup> ; Fairman et al., 2017 <sup>[[#fn:r835|835]]</sup> ); cf. 3.4.3.2 Ecosystems and their Services) ( ''high confidence'' ). For example, in the Western USA, mountain ecosystems are experiencing an increase in the number and extent of wildfires, which have been attributed to many factors, including climate factors such as earlier snowmelt and vapour-pressure deficit (Settele et al., 2014 <sup>[[#fn:r836|836]]</sup> ; Westerling, 2016 <sup>[[#fn:r837|837]]</sup> ; Kitzberger et al., 2017 <sup>[[#fn:r838|838]]</sup> ; Littell, 2018 <sup>[[#fn:r839|839]]</sup> ; Littell et al., 2018 <sup>[[#fn:r840|840]]</sup> ). Similarly, landslides and floods in many areas have been attributed to cryospheric changes (Section 2.3.2). Disturbances can feedback and diminish many of the ecosystem services such as provisioning, regulating and cultural services (Millar and Stephenson, 2015 <sup>[[#fn:r841|841]]</sup> ; McDowell and Koppes, 2017 <sup>[[#fn:r842|842]]</sup> ; Mcdowell et al., 2018 <sup>[[#fn:r843|843]]</sup> ; Murphy et al., 2018 <sup>[[#fn:r844|844]]</sup> ; Maxwell et al., 2019 <sup>[[#fn:r845|845]]</sup> ). Consistent with AR5 findings (Settele et al., 2014 <sup>[[#fn:r846|846]]</sup> ) the capacity of many freshwater and terrestrial mountain species to adapt naturally to climate change is projected to be exceeded for high warming levels, leading to species migration across mountain ranges or loss with consequences for many ecosystem services (Elsen and Tingley, 2015 <sup>[[#fn:r847|847]]</sup> ; Dobrowski and Parks, 2016 <sup>[[#fn:r848|848]]</sup> ; Pecl et al., 2017 <sup>[[#fn:r849|849]]</sup> ; Rumpf et al., 2019 <sup>[[#fn:r850|850]]</sup> ) ( ''robust evidence'' , ''medium agreement'' , i.e., ''high confidence'' ). Although the adaptive potential of aquatic biota to projected changes in glacial runoff is not fully understood (Lencioni et al., 2015 <sup>[[#fn:r851|851]]</sup> ), dispersion and phenotypic plasticity together with additional microrefugia formation due to cryospheric changes, is expected to help threatened species to better adapt, perhaps even in the long term (Shama and Robinson, 2009 <sup>[[#fn:r852|852]]</sup> ). Likewise, traits shaped by climate and with high genetically-based standing variation may be used to spatially identify, map and manage global ‘hotspots’ for evolutionary rescue from climate change (Jones et al., 2018 <sup>[[#fn:r853|853]]</sup> ; Mills et al., 2018 <sup>[[#fn:r854|854]]</sup> ). Nature conservation increases the potential for mitigating adverse effects on many of these ecosystem services, including those that are essential for the support of the livelihoods and the culture of mountain peoples, including economical aspects such as recreation and tourism (e.g., Palomo, 2017; Elsen et al., 2018 <sup>[[#fn:r855|855]]</sup> ; Wester et al., 2019 <sup>[[#fn:r856|856]]</sup> ) ( ''medium confidence'' ).

<span id="infrastructure-and-mining"></span>
=== 2.3.4 Infrastructure and Mining ===

<div id="section-2-3-4infrastructure-and-mining-block-1"></div>

There is ''high confidence'' that permafrost thaw has had negative impacts on the integrity of infrastructure in high mountain areas. Like in polar regions (Section 3.4.3.3.4), the local effects of infrastructure together with climate change degraded permafrost beneath and around structures (Dall’Amico et al., 2011 <sup>[[#fn:r857|857]]</sup> ; Doré et al., 2016 <sup>[[#fn:r858|858]]</sup> ) Infrastructure on permafrost in the European Alps, mostly found near mountain summits but not in major valleys, has been destabilised by permafrost thaw, including mountain stations in France and Austria (Ravanel et al., 2013 <sup>[[#fn:r859|859]]</sup> ; Keuschnig et al., 2015 <sup>[[#fn:r860|860]]</sup> ; Duvillard et al., 2019 <sup>[[#fn:r861|861]]</sup> ) as well as avalanche defence structures (Phillips and Margreth, 2008 <sup>[[#fn:r862|862]]</sup> ) and a ski lift (Phillips et al., 2007 <sup>[[#fn:r863|863]]</sup> ) in Switzerland. On the Tibetan Plateau, deformation or damage has been found on roads (Yu et al., 2013 <sup>[[#fn:r864|864]]</sup> ; Chai et al., 2018 <sup>[[#fn:r865|865]]</sup> ), power transmission infrastructure (Guo et al., 2016 <sup>[[#fn:r866|866]]</sup> ) and around an oil pipeline (Yu et al., 2016 <sup>[[#fn:r867|867]]</sup> ). For infrastructure on permafrost, engineering practices suitable for polar and high mountain environments (Doré et al., 2016 <sup>[[#fn:r868|868]]</sup> ) as well as specific for steep terrain (Bommer et al., 2010 <sup>[[#fn:r869|869]]</sup> ) have been developed to support adaptation.

In some mountain regions, glacier retreat and related processes of change in the cryosphere have afforded greater accessibility for extractive industries and related activities to mine minerals and metals ( ''medium confidence'' ). Accelerated glacier shrinkage and retreat have been reported to facilitate mining activities in Chile, Argentina and Peru (Brenning, 2008 <sup>[[#fn:r870|870]]</sup> ; Brenning and Azócar, 2010 <sup>[[#fn:r871|871]]</sup> ; Anacona et al., 2018 <sup>[[#fn:r872|872]]</sup> ), and Kyrgyzstan (Kronenberg, 2013 <sup>[[#fn:r873|873]]</sup> ; Petrakov et al., 2016 <sup>[[#fn:r874|874]]</sup> ), which also interact with and have consequences for other social, cultural, economic, political and legal measures, where climate change impacts also play a role (Brenning and Azócar, 2010 <sup>[[#fn:r875|875]]</sup> ; Evans et al., 2016 <sup>[[#fn:r876|876]]</sup> ; Khadim, 2016 <sup>[[#fn:r877|877]]</sup> ; Anacona et al., 2018 <sup>[[#fn:r878|878]]</sup> ). However, negative impacts due to cryosphere changes may also occur. One study projects that reductions in glacier melt water and snowmelt in the watershed in the Chilean Andes will lead to a reduction of water supply to a copper mine by 2075–2100 of 28% under scenario A2 and of 6% under B2; construction of infrastructure to draw water from other sources will cost between 16–137 million USD (Correa-Ibanez et al., 2018 <sup>[[#fn:r879|879]]</sup> ).

Conversely, there is also evidence suggesting that some of these mining activities affect glaciers locally, and the mountain environment around them, further altering glacier dynamics, glacier structure and permafrost degradation. This is due mainly to excavation, extraction, and use of explosives (Brenning, 2008 <sup>[[#fn:r880|880]]</sup> ; Brenning and Azócar, 2010 <sup>[[#fn:r881|881]]</sup> ; Kronenberg, 2013 <sup>[[#fn:r882|882]]</sup> ), and deposition of dust and other mine waste material close to or top of glaciers during extraction and transportation (Brenning, 2008 <sup>[[#fn:r883|883]]</sup> ; Torgoev and Omorov, 2014 <sup>[[#fn:r884|884]]</sup> ; Arenson et al., 2015b <sup>[[#fn:r885|885]]</sup> ; Jamieson et al., 2015 <sup>[[#fn:r886|886]]</sup> ). These activities have reportedly generated slope instabilities (Brenning, 2008 <sup>[[#fn:r887|887]]</sup> ; Brenning and Azócar, 2010 <sup>[[#fn:r888|888]]</sup> ; Torgoev and Omorov, 2014 <sup>[[#fn:r889|889]]</sup> ), glacier mass loss due to enhanced surface melt from dust and debris deposition (Torgoev and Omorov, 2014 <sup>[[#fn:r890|890]]</sup> ; Arenson et al., 2015b <sup>[[#fn:r891|891]]</sup> ; Petrakov et al., 2016 <sup>[[#fn:r892|892]]</sup> ), and even glacier advance by several kilometres (Jamieson et al., 2015 <sup>[[#fn:r893|893]]</sup> ), although their impact is considered less than that reported for changes in glaciers due to climatic change ( ''limited evidence, medium agreement'' ). Glacier Protection Laws and similar measures have been introduced in countries such as Chile and Argentina to address these impacts (Khadim, 2016 <sup>[[#fn:r894|894]]</sup> ; Anacona et al., 2018 <sup>[[#fn:r895|895]]</sup> ; Navarro et al., 2018 <sup>[[#fn:r896|896]]</sup> ). In addition, the United Nations Human Rights Council passed a declaration in 2018 to “ protect and restore water-related ecosystems” in mountain areas as elsewhere from contamination by mining (UNHRC, 2018 <sup>[[#fn:r897|897]]</sup> ); however, evidence on the effectiveness of these measures remains inconclusive.

<span id="tourism-and-recreation"></span>
=== 2.3.5 Tourism and Recreation ===

<div id="section-2-3-5tourism-and-recreation-block-1"></div>

The mountain cryosphere provides important aesthetic, cultural, and recreational services to society (Xiao et al., 2015 <sup>[[#fn:r898|898]]</sup> ). These services support tourism, providing economic contributions and livelihood options to mountain communities and beyond. The relevant changes in the cryosphere affecting mountain tourism and recreation include shorter seasons of snow cover, more winter precipitation falling as rain instead of snow, and declining glaciers and permafrost (Sections 2.2.1, 2.2.2, 2.2.3 and 2.2.4). Downhill skiing, the most popular form of snow recreation, occurs in 67 countries (Vanat, 2018 <sup>[[#fn:r899|899]]</sup> ). The Alps in Europe support the largest ski industry (Vanat, 2018 <sup>[[#fn:r900|900]]</sup> ). In Europe, the growth of alpine skiing and winter tourism after 1930 brought major economic growth to alpine regions and transformed winter sports into a multi-billion USD industry (Denning, 2014 <sup>[[#fn:r901|901]]</sup> ). Sixteen percent of skier visits occur in the USA, where expenditures from all recreational snow sports generated more than 695,000 jobs and 72.7 billion USD in trip-related spending in 2016 (Outdoor Industry Association, 2017 <sup>[[#fn:r902|902]]</sup> ). While the number of ski resorts in the USA has been decreasing since the 1980s, China added 57 new ski resorts in 2017 (Vanat, 2018 <sup>[[#fn:r903|903]]</sup> ). Although the bulk of economic activity is held within mountain communities, supply chains for production of ski equipment and apparel span the globe. Steiger et al. (2017) <sup>[[#fn:r904|904]]</sup> point out that Asia, Africa and South America are underrepresented in the ski tourism literature, and Africa and the Middle East are not significant markets from a ski tourism perspective.

Skiing’s reliance on favourable atmospheric and snow conditions make it particularly vulnerable to climate change (Arent et al., 2014 <sup>[[#fn:r905|905]]</sup> ; Hoegh-Guldberg et al., 2018 <sup>[[#fn:r906|906]]</sup> ). Snow reliability, although not universally defined, quantifies whether the snow cover is sufficient for ski resorts operations. Depending on the context, it focuses on specific periods of the winter season, and may account for interannual variability and/or for snow management (Steiger et al., 2017 <sup>[[#fn:r907|907]]</sup> ). The effects of less snow, due to strong correlation between snow cover and skier visits, cost the USA economy 1 billion USD and 17,400 jobs per year between 2001–2016 in years of less seasonal snow (Hagenstad et al., 2018 <sup>[[#fn:r908|908]]</sup> ). Efforts to reduce climate change impacts and risks to economic losses focus on increased snowmaking, such as artificial production of snow (Steiger et al., 2017 <sup>[[#fn:r909|909]]</sup> ), summertime slope preparation (Pintaldi et al., 2017 <sup>[[#fn:r91+|91+]]</sup> ), grooming (Steiger et al., 2017 <sup>[[#fn:r911|911]]</sup> ), and snow farming, that is, storage of snow (Grünewald et al., 2018 <sup>[[#fn:r912|912]]</sup> ). The effectiveness of snow management methods as adaptation to long-term climate change depends on sufficiently low air temperature conditions needed for snowmaking, water and energy availability, compliance with environmental regulations (de Jong, 2015), and ability to pay for investment and operating costs. When these requirements are met, evidence over the past decades shows that snow management methods have generally proven efficient in reducing the impact of reduced natural snow cover duration for many resorts (Dawson and Scott, 2013 <sup>[[#fn:r913|913]]</sup> ; Hopkins and Maclean, 2014 <sup>[[#fn:r914|914]]</sup> ; Steiger et al., 2017 <sup>[[#fn:r915|915]]</sup> ; Spandre et al., 2019a <sup>[[#fn:r916|916]]</sup> ). The number of skier visits was found to be 39% less sensitive to natural snow variations in Swiss ski resorts with 30% areal snowmaking coverage (representing the national average), compared to resorts without snowmaking (Gonseth, 2013 <sup>[[#fn:r917|917]]</sup> ). In some regions, many resorts (mostly smaller, low-elevation resorts) have closed due to unfavourable snow conditions brought on by climate change and/or the associated need for large capital investments for snowmaking capacities (e.g., in northeast USA; Beaudin and Huang, 2014 <sup>[[#fn:r918|918]]</sup> )). To offset loss in ski tourism revenue, a key adaptation strategy is diversification, offering other non-snow recreation options such as mountain biking, mountain coasters and alpine slides, indoor climbing walls and water parks, festivals and other special events (Figure 2.9; Hagenstad et al., 2018 <sup>[[#fn:r919|919]]</sup> ; Da Silva et al., 2019).

In the near term (2031–2050) and regardless of the greenhouse gas emission scenario, risks to snow reliability exist for many resorts, especially at lower elevation, although snow reliability is projected to be maintained at many resorts in North America (Wobus et al., 2017 <sup>[[#fn:r920|920]]</sup> ) and in the European Alps, Pyrenees and  Scandinavia (Marke et al., 2015 <sup>[[#fn:r921|921]]</sup> ; Steiger et al., 2017 <sup>[[#fn:r922|922]]</sup> ; Scott et al., 2019 <sup>[[#fn:r923|923]]</sup> ; Spandre et al., 2019a <sup>[[#fn:r924|924]]</sup> ; Spandre et al., 2019b <sup>[[#fn:r925|925]]</sup> ). At the end of the century (2081–2100), under RCP8.5, snow reliability is projected to be unviable for most ski resorts under current operating practices in North America, the European Alps and Pyrenees, Scandinavia and Japan, with some exceptions at high elevation or high-latitudes (Steiger et al., 2017 <sup>[[#fn:r926|926]]</sup> ; Wobus et al., 2017 <sup>[[#fn:r927|927]]</sup> ; Suzuki-Parker et al., 2018 <sup>[[#fn:r928|928]]</sup> ; Scott et al., 2019 <sup>[[#fn:r929|929]]</sup> ; Spandre et al., 2019a <sup>[[#fn:r930|930]]</sup> ; Spandre et al., 2019b <sup>[[#fn:r931|931]]</sup> ). Only few studies have used RCP2.6 in the context of ski tourism, and results indicate that the risks at the end of the century (2081–2100) are expected to be similar to the near term impacts (2031–2050) for RCP8.5 (Scott et al., 2019 <sup>[[#fn:r932|932]]</sup> ; Spandre et al., 2019a <sup>[[#fn:r933|933]]</sup> ).

The projected economic losses reported in the literature include an annual loss in hotel revenues of EUR 560 million  (2012 value) in Europe, compared to the period 1971–2000 under a 2°C global warming scenario (Damm et al., 2017 <sup>[[#fn:r935|935]]</sup> ). This estimate includes population projections but does not account for snow management. In the USA, Wobus et al. (2017) estimate annual revenue losses from tickets (skiing) and day fees (cross country skiing and snowmobiling) due to reduced snow season length, will range from 340–780 million USD in 2050 for RCP4.5 and RCP8.5, respectively, and from 130 million to 2 billion USD in 2090 for RCP4.5 and RCP8.5 respectively, taking into account snow management and population projections. Total economic losses from these studies would be much higher if all costs were included (costs for tickets, transport, lodging, food and equipment). Regardless of the climate scenario, as risk of financial unviability increases, there are reported expectations that companies would need to forecast when their assets may become stranded assets and require devaluation or conversion to liabilities, and report this on their balance sheets (Caldecott et al., 2016 <sup>[[#fn:r936|936]]</sup> ). Economic impacts are projected to occur in other snow-based winter activities including events (e.g., ski races) and other recreation activities such as cross-country skiing, snowshoeing, backcountry skiing, ice climbing, sledding, snowmobiling and snow tubing. By 2050, 13 (out of 21) prior Olympic Winter Games locations are projected to exhibit adequate snow reliability under RCP2.6, and 10 under RCP8.5. By 2080, the number decreases to 12 and 8, respectively (Scott et al., 2018 <sup>[[#fn:r937|937]]</sup> ). Even for cities remaining cold enough to host ski competitions, costs are projected to rise for making and stockpiling snow, as was the case in Sochi, Russia in 2014 and Vancouver, Canada in 2010 (Scott et al., 2018 <sup>[[#fn:r938|938]]</sup> ), and preserving race courses through salting (Hagenstad et al., 2018 <sup>[[#fn:r939|939]]</sup> ).

In summer, cryosphere changes are impacting glacier-related activities (hiking, sightseeing, skiing, climbing and mountaineering) (Figure 2.8). In recent years, several ski resorts operating on glaciers have ceased summer operations due to unfavourable snow conditions and excessive operating costs (e.g., Falk, 2016). Snow management and snowmaking are increasingly used on glaciers (Fischer et al., 2016 <sup>[[#fn:r940|940]]</sup> ). Glacier retreat has led to increased moraine instability which can compromise hiker and climber safety along established trails and common access routes, for example, in Iceland (Welling et al., 2019 <sup>[[#fn:r941|941]]</sup> ), though it has made some areas in the Peruvian Andes more accessible to trekkers (Vuille et al., 2018 <sup>[[#fn:r942|942]]</sup> ). In response, some hiking routes have been adjusted and ladders and fixed anchors installed (Duvillard et al., 2015 <sup>[[#fn:r943|943]]</sup> ; Mourey and Ravanel, 2017 <sup>[[#fn:r944|944]]</sup> ). As permafrost thaws, rock falls on and off glaciers are increasingly observed, threatening the safety of hikers and mountaineers, for example, in Switzerland (Temme, 2015 <sup>[[#fn:r945|945]]</sup> ) and New Zealand (Purdie et al., 2015 <sup>[[#fn:r946|946]]</sup> ). Glacier retreat and permafrost thaw have induced major changes to iconic mountaineering routes in the Mont Blanc area with impacts on mountaineering practices, such as shifts in suitable climbing seasons, and reduced route safety (Mourey and Ravanel, 2017 <sup>[[#fn:r947|947]]</sup> ; Mourey et al., 2019 <sup>[[#fn:r948|948]]</sup> ). Cryosphere decline has also reduced opportunities for ice climbing and reduced attractions for summer trekking in the Cascade Mountains, USA (Orlove et al., 2019 <sup>[[#fn:r949|949]]</sup> ). In response to these impacts, tour companies have shifted to new sites, diversified to offer other activities or simply reduced their activities (Furunes and Mykletun, 2012 <sup>[[#fn:r950|950]]</sup> ) (Figure 2.9). Steps to improve consultation and participatory approaches to understand risk perception and design joint action between affected communities, authorities and operators, are evident, for example, in Iceland (Welling et al., 2019 <sup>[[#fn:r951|951]]</sup> ). In some cases, new opportunities are presented such as marketing ‘climate change tourism’ where visitors are attracted by ‘last chance’ opportunities to view a glacier; for example, in New Zealand (Stewart et al., 2016 <sup>[[#fn:r952|952]]</sup> ), in China (Wang et al., 2010 <sup>[[#fn:r953|953]]</sup> ) or through changing landscapes such as new lakes, for instance in Iceland (Þórhallsdóttir and Ólafsson, 2017 <sup>[[#fn:r954|954]]</sup> ), or to view the loss of a glacier, for example, in the Bolivian Andes (Kaenzig et al., 2016 <sup>[[#fn:r955|955]]</sup> ). The opening of a trekking route promoting this opportunity created tensions between a National Park and a local indigenous community in the Peruvian Andes over the management and allocation of revenue from the route (Rasmussen, 2019 <sup>[[#fn:r956|956]]</sup> ). The consequences of ongoing and future glacier retreat are projected to negatively impact trekking and mountaineering in the Himalaya (Watson and King, 2018 <sup>[[#fn:r957|957]]</sup> ). Reduced snow cover has also negatively impacted trekking in the Himalaya, since tourists find the mountains less attractive as a destination, and the reduced water availability affects the ability of hotels and campsites to serve visitors (Becken et al., 2013 <sup>[[#fn:r958|958]]</sup> ).

In summary, financial risks to mountain communities that depend on tourism for income, are high and include losses to revenues generated from recreation primarily in the winter season. Adaptation to cryosphere change for ski tourism focuses on snowmaking and is expected to be moderately effective for many locations in the near term (2031–2050), but it is unlikely to substantially reduce the risks in most locations in the longer term (end of century) ( ''high confidence'' ). Determining the extent to which glacier retreat and permafrost thaw impact upon overall visitor numbers in summer tourism, and how any losses or increased costs are offset by opportunities, is inconclusive. Furthermore, tourism is also impacted by cryospheric change that impacts on water resources availability, increasing competition for its use (Section 2.3.1.3).

<div id="section-2-3-5tourism-and-recreation-block-2"></div>

<span id="figure-2.9"></span>
<!-- START IMG -->
<!-- IMG TITLE -->
'''Figure 2.9'''

<span id="figure-2.9-a-documented-number-of-individual-adaptation-actions-distributed-across-seven-of-the-high-mountain-regions-addressed-in-this-chapter-with-pie-charts-indicating-the-number-of-adaptation-measures-for-sectors-addressed-in-this-chapter-left-pie-chart-and-the-relative-proportion-of-these-classified-as-either-formal-autonomous-or-undefined-right-pie"></span>
<!-- IMG CAPTION -->
'''Figure 2.9 | a) Documented number of individual adaptation actions distributed across seven of the high mountain regions addressed in this Chapter, with pie charts indicating the number of adaptation measures for sectors addressed in this chapter (left pie chart), and the relative proportion of these classified as either ‘formal’, ‘autonomous’ or ‘undefined’ (right pie […]'''
<!-- IMG FILE -->
[[File:5663c8409ff51deab2d5cb5f9d835eaa IPCC-SROCC-CH_2_9.jpg]]

Figure 2.9 | a) Documented number of individual adaptation actions distributed across seven of the high mountain regions addressed in this Chapter, with pie charts indicating the number of adaptation measures for sectors addressed in this chapter (left pie chart), and the relative proportion of these classified as either ‘formal’, ‘autonomous’ or ‘undefined’ (right pie chart). Note that for regions with less than five reported adaptation measures were excluded from the figure (i.e., Caucasus, Iceland and Alaska), however these are detailed in Table SM2.9. b) Number of publications reported in the assessed literature over time. In some cases, multiple adaptation measures are discussed in a single publication (Table SM2.9).

<!-- END IMG -->
<span id="cultural-values-and-human-well-being">
</span>
=== 2.3.6 Cultural Values and Human Well-being ===

<div id="section-2-3-6cultural-values-and-human-well-being-block-1"></div>

Cryosphere changes also impact cultural values, which are held by populations in high mountains and other regions around the world; these impacts often harm human well-being (Tschakert et al., 2019 <sup>[[#fn:r959|959]]</sup> ) ( ''medium evidence, high agreement'' ). Cultural values were covered extensively in AR5, with particular emphasis on small island states and the Arctic; the research on cultural values in high mountain regions is relatively new. Out of a total of 247 UNESCO World Heritage natural sites recognised for their outstanding universal value, 46 sites include glaciers within their boundaries, where the presence of glaciers is stated among the principal reason (5 sites), or secondary reason (28 sites), for World Heritage inscription; complete glacier extinction is projected by 2100 in 8 to 21 of these sites, under RCP2.6 and RCP8.5 scenarios, respectively, compromising the outstanding universal value placed on these sites, which have been inscribed at least partly for their exceptional glaciers (Bosson et al., 2019 <sup>[[#fn:r960|960]]</sup> ). UNESCO defines “outstanding universal value” as “ cultural and/or natural significance which is so exceptional as to transcend national boundaries and to be of common importance for present and future generations of all humanity” ( UNESCO, 2012 <sup>[[#fn:r961|961]]</sup> ). Furthermore, in recognising the importance of the cultural and intangible value placed by communities on aspects of their surrounding environment, such as those afforded by cryosphere elements in the high mountains, are mentioned under the workplan of the Warsaw International Mechanism as a specific work area under ‘Non-economic loss and damage’ ( UNFCCC Secretariat, 2014 <sup>[[#fn:r962|962]]</sup> ; Serdeczny, 2019 <sup>[[#fn:r963|963]]</sup> ).

Cultural values include spiritual, intrinsic and existence values, as well as aesthetic dimensions, which are also an element of tourism and recreation (Section 2.3.5), though they focus more directly on ties to sacred beings or to inherent rights of entities to exist. However, these values overlap, since the visual appeal of natural landscapes links with a sense of the immensity of mountain landscapes, glaciers and fresh snow (Paden et al., 2013 <sup>[[#fn:r964|964]]</sup> ; Gagné et al., 2014 <sup>[[#fn:r965|965]]</sup> ). Moreover, different stakeholders, such as local communities, tourists and policymakers, may place different emphasis on specific cultural values (Schirpke et al., 2016 <sup>[[#fn:r966|966]]</sup> ). For the indigenous Manangi community of the Annapurna Conservation Area of Nepal, the loss of glaciers which they have observed threatens their ethnic identity (Konchar et al., 2015 <sup>[[#fn:r967|967]]</sup> ). Villagers in the Italian Alps also report that glacier retreat weakens their identity (Jurt et al., 2015 <sup>[[#fn:r968|968]]</sup> ).

Spiritual and intrinsic values in high mountain regions often, but not exclusively, rest on deeply held religious beliefs and other local customs ( ''medium evidence, high agreement'' ). Some communities understand mountains through a religious framework (Bernbaum, 2006 <sup>[[#fn:r969|969]]</sup> ). In settings as diverse as the Peruvian Andes, the Nepal Himalaya, the Alps, the North Cascades (USA), Mount Kilimanjaro and the Hengduan Mountains of southwest China, local populations view glacier retreat as the product of their failure to show respect to sacred beings or to follow proper conduct. Experiencing deep concern that they have disturbed cosmic order, they seek to behave in closer accord with established traditions; they anticipate that the retreat will continue, leading to further environmental degradation and to the decline of natural and social orders—a prospect which causes them distress (Becken et al., 2013 <sup>[[#fn:r970|970]]</sup> ; Gagné et al., 2014 <sup>[[#fn:r971|971]]</sup> ; Allison, 2015 <sup>[[#fn:r972|972]]</sup> ). In the USA, the snow covered peaks of the Cascades have also evoked a deep sense of awe and majesty, and an obligation to protect them (Carroll, 2012 <sup>[[#fn:r973|973]]</sup> ; Duntley, 2015 <sup>[[#fn:r974|974]]</sup> ). Similar views are found in the Italian Alps, where villagers speak of treating glacier peaks with “respect,” and state that glacier retreat is due, at least in part, to humans “disturbing” the glaciers (Brugger et al., 2013 <sup>[[#fn:r975|975]]</sup> ), resulting in an emotion which Albrecht et al. (2007) <sup>[[#fn:r976|976]]</sup> termed solastalgia, a kind of deep environmental distress or ecological grief (Cunsolo and Ellis, 2018 <sup>[[#fn:r977|977]]</sup> ).

Glacier retreat threatens the Indigenous knowledge and local knowledge of populations in mountain regions; this knowledge constitutes a cultural service to wider society by contributing to scientific understanding of glaciers (Cross-Chapter Box 4 in Chapter 1). Though this knowledge is dynamic, and records previous states of glaciers, it has been undermined by the complete disappearance of glaciers in a local area (Rhoades et al., 2008 <sup>[[#fn:r978|978]]</sup> ). This knowledge of glaciers is often tied to religious beliefs and practices. It is based on direct observation, stories passed down from one generation to another within community, placenames, locations of structures and other sources (Gagné et al., 2014 <sup>[[#fn:r979|979]]</sup> ). Residents of mountain areas can provide dates for previous locations of glacier fronts, sometimes documenting these locations through the presence of structures (Brugger et al., 2013 <sup>[[#fn:r980|980]]</sup> ). Much like other cases of data from citizen science (Theobald et al., 2015 <sup>[[#fn:r981|981]]</sup> ), their observations often overlap with the record of instrumental observations (Deng et al., 2012 <sup>[[#fn:r982|982]]</sup> ), and can significantly extend this record (Mark et al., 2010 <sup>[[#fn:r983|983]]</sup> ).

An additional cultural value is the contribution of glaciers to the understanding of human history. Glacier retreat has supported the increase of knowledge of past societies by providing access to archaeological materials and other cultural resources that had previously been covered by ice. The discovery of Oetzi, a mummified Bronze Age man whose remains were discovered in 1991 in the Alps near the Italian-Austrian border, marked the beginning of scientific research with such materials (Putzer and Festi, 2014 <sup>[[#fn:r984|984]]</sup> ). Subsequent papers described objects that were uncovered in retreating glaciers and shrinking ice patches in the Wrangell-Saint Elias Range (Dixon et al., 2005 <sup>[[#fn:r985|985]]</sup> ), the Rocky Mountains (Lee, 2012) and Norway (Bjørgo et al., 2016 <sup>[[#fn:r986|986]]</sup> ). This field provides new insight into human cultural history and contributes to global awareness of climate change (Dixon et al., 2014 <sup>[[#fn:r987|987]]</sup> ). Though climate change permits the discovery of new artefacts and sites, it also threatens these objects and places, since they become newly exposed to harsh weather (Callanan, 2016 <sup>[[#fn:r988|988]]</sup> ).

<span id="migration-habitability-and-livelihoods"></span>
=== 2.3.7 Migration, Habitability and Livelihoods ===

<div id="section-2-3-7migration-habitability-and-livelihoods-block-1"></div>

High mountain communities have historically included mobility in their sets of livelihood strategies, as a means to gain access to production zones at different elevations within mountain zones and in lowland areas, and as a response to the strong seasonality of agricultural and pastoral livelihoods. Cryosphere changes in high mountain areas have influenced human mobility and migration during this century by altering water availability and increasing exposure to mass movements and floods and other cryospheric induced disasters (Figure 2.7) (Barnett et al., 2005 <sup>[[#fn:r989|989]]</sup> ; Carey et al., 2017 <sup>[[#fn:r990|990]]</sup> ; Rasul and Molden, 2019 <sup>[[#fn:r991|991]]</sup> ). These changes affect three forms of human mobility: transhumant pastoralism, temporary or permanent wage labour migration and displacement, in which entire communities resettle in new areas.

Transhumant pastoralism, involving movements between summer and winter pastures, is a centuries old practice in high mountain areas (Lozny, 2013 <sup>[[#fn:r992|992]]</sup> ). In High Mountain Asia and other regions, it is declining due to both climatic factors, including changes in snow distribution and glaciers, and to non-climatic factors, and is projected to continue declining, at least in the short term ( ''medium evidence, high agreement'' ). The changes in snow and glaciers adversely affect herders at their summer residences and winter camps in the Himalaya (Namgay et al., 2014 <sup>[[#fn:r993|993]]</sup> ) and in Scandinavian mountains (Mallory and Boyce, 2018 <sup>[[#fn:r994|994]]</sup> ). Reduced winter snowfall has led to poorer pasture quality in Nepal (Gentle and Maraseni, 2012 <sup>[[#fn:r995|995]]</sup> ) and India (Ingty, 2017 <sup>[[#fn:r996|996]]</sup> ). Other climate change impacts, including erratic snowfall patterns and a decrease in rainfall, are perceived by herders in Afghanistan, Nepal and Pakistan to have resulted in vegetation of lower quality and quantity (Shaoliang et al., 2012 <sup>[[#fn:r997|997]]</sup> ; Joshi et al., 2013 <sup>[[#fn:r998|998]]</sup> ; Gentle and Thwaites, 2016 <sup>[[#fn:r999|999]]</sup> ). Heavy snowfall incidents in winter caused deaths of a large number of livestock in northern Pakistan in 2009 (Shaoliang et al., 2012 <sup>[[#fn:r1000|1000]]</sup> ). Herders in Nepal reported of water scarcity in traditional water sources along migration routes (Gentle and Thwaites, 2016 <sup>[[#fn:r1001|1001]]</sup> ). Increased glacier melt water has caused lakes on the Tibetan Plateau to increase in size, covering pasture areas and leading pastoralists to alter their patterns of seasonal movement (Nyima and Hopping, 2019 <sup>[[#fn:r1002|1002]]</sup> ). However, rising temperatures, with associated effects on snow cover, have some positive impacts. Seasonal migration from winter to summer pastures start earlier in Northern Pakistan, and residence in summer pasture lasts longer (Joshi et al., 2013 <sup>[[#fn:r1003|1003]]</sup> ), as it does in Afghanistan (Shaoliang et al., 2012 <sup>[[#fn:r1004|1004]]</sup> ).

Wage labour migration is also a centuries old practice in the Himalaya, the Andes and the European Alps (Macfarlane, 1976 <sup>[[#fn:r1005|1005]]</sup> ; Cole, 1985 <sup>[[#fn:r1006|1006]]</sup> ; Viazzo, 1989 <sup>[[#fn:r1007|1007]]</sup> ). Studies show that migration is a second-order effect of cryosphere changes, since the first-order effects, a decrease in agricultural production (Section 2.3.1.3.2), have led to increased wage labour migration to provide supplementary income in a number of regions ( ''medium evidence, high agreement)'' . Wage labour migration linked to cryosphere changes occurs on several time scales, including short-term, long-term and permanent migration, and on different spatial scales. Though migration usually takes place within the country of origin, and sometimes within the region, cases of international migration have also been recorded (Merrey et al., 2018 <sup>[[#fn:r1008|1008]]</sup> ). The studies since AR5 on migration driven by cryosphere changes are concentrated in High Mountain Asia and the Andes, supporting the finding, reported in AR5 Working Group II (Section 12.7), that stress on livelihoods is an important driver of climate change induced migration. The research on such migration also supports the finding in SR15 (Section 4.3.5.6) that migration can have mixed outcomes on reducing socioeconomic vulnerability, since cases of increase and of reduction of vulnerability are both found in migration from high mountain regions that is driven by cryosphere changes.

Changing water availability, mass movements and floods are cryosphere processes which drive wage labour migration ( ''medium evidence, high agreement'' ). A debris flow in central Nepal in 2014, in a region where landslides have increased in recent decades, led more than half the households to migrate for months (van der Geest and Schindler, 2016 <sup>[[#fn:r1009|1009]]</sup> ). In the Santa River drainage, Peru, rural populations have declined 10% between 1970–2000, and the area of several major subsistence crops also declined (Bury et al., 2013 <sup>[[#fn:r1010|1010]]</sup> ). Research in this region suggests that seasonal wage labour migration from small basins within the main Santa basin is largest in the small drainages in which glacier retreat has reduced melt water flow most significantly; where this process is not as acute, and streamflow is less reduced, migration rates are lower  (Wrathall et al., 2014 <sup>[[#fn:r1011|1011]]</sup> ). A study from a region in the central Peruvian Andes shows that the residents of the villages that have the highest dependence on glacier melt water travel further and stay away longer than the residents of the villages where glacier melt water forms a smaller portion of stream flow (Milan and Ho, 2014 <sup>[[#fn:r1012|1012]]</sup> ). However, the inverse relation between reliance on cryosphere-related water sources and migration was noted in a case in the Naryn River drainage in Kyrgyzstan, where the villages that are more dependent on glacier melt water had lower, rather than higher, rates of wage labour migration than the villages which were less dependent on it; the villages with lower rates of such migration also had more efficient water management institutions than the others (Hill et al., 2017 <sup>[[#fn:r1013|1013]]</sup> ). Several studies, which project cryosphere-related emigration to continue in the short term, emphasise decreased water availability, due to glacier retreat as a driver in Kyrgyzstan (Chandonnet et al., 2016 <sup>[[#fn:r1014|1014]]</sup> ) and Peru (Oliver-Smith, 2014 <sup>[[#fn:r1015|1015]]</sup> ), and to reduced snow cover in Nepal (Prasain, 2018 <sup>[[#fn:r1016|1016]]</sup> ). In most cases, climate is only one of several drivers (employment opportunities and better educational and health services in lowland areas are others).

Several studies show that wage labour migration is more frequent among young adults than among other age groups, supporting the observation in AR5 that climate change migrants worldwide are concentrated in this age ( ''limited evidence, high agreement'' ). This age-specific pattern is found in a valley in Northern Pakistan in which agriculture relies on glacier melt water for irrigation; as river flow decreases, the returns to agricultural labour have declined, and emigration has increased, particularly among the youth, who are assigned, by local cultural practices, to carry out the heaviest work (Parveen et al., 2015 <sup>[[#fn:r1017|1017]]</sup> ). Emigration has increased in recent decades from two valleys in highland Bolivia which rely on glacier melt water, as water supplies have declined, though other factors also contribute to emigration, including land fragmentation, increasing household needs for income, the lack of local wage-labour opportunities and an interest among the young in educational opportunities located in cities (Brandt et al., 2016 <sup>[[#fn:r1018|1018]]</sup> ). In Nepal, young members of high-elevation pastoral households impacted by cryosphere change have been increasingly engaged in tourism and labour migration since 2000 (Shaoliang et al., 2012 <sup>[[#fn:r1019|1019]]</sup> ); similar responses are reported for Sikkim in the Indian Himalaya (Ingty, 2017 <sup>[[#fn:r1020|1020]]</sup> ). A recent study documents the inter-generational dynamics of emigration from a livestock raising community in the Peruvian Andes, where glacier retreat has led to reduced streamflow that supports crucial dry season pasture (Alata et al., 2018 <sup>[[#fn:r1021|1021]]</sup> ). Though people 50 years old or older in this community are accustomed to living in the high pasture zones, younger people use livestock raising as a means of accumulating capital. They sell off their animals and move to towns at lower elevations. This loss of young adults has reduced the capacity of households to undertake the most demanding tasks, particularly in periods of inclement weather, accelerating the decline of herding. As a result, the human and animal populations of the communities are shrinking.

Recent research on cryosphere driven migration shows some cases of complex livelihood interactions or feedback loops, in which migration is not merely a result of changes in agricultural livelihoods, but also has impacts, either positive or negative, on these livelihoods ( ''medium confidence).'' In some instances, the different livelihood strategies complement each other to support income and well-being. A review of migration in the Himalaya and Hindu Kush found that households that participated in labour migration and received remittances had improved adaptive capacity, and lowered exposure to natural hazards (Banerjee et al., 2018 <sup>[[#fn:r1022|1022]]</sup> ). In other cases, the households and communities, which undertake wage labour migration, encounter conflicts or incompatibilities between migration and agricultural livelihoods. Sustainable management of land, water and other resources is highly labour intensive, and hence labour mobility constrains and limits the adoption of sustainable practices (Gilles et al., 2013 <sup>[[#fn:r1023|1023]]</sup> ). Moreover, the labour available to a household is differentiated by age. In Northern Pakistan, where cryosphere changes are reducing streamflow the emigration of young people has led to a decline not only in the labour in fields and orchards, but also a decline in the maintenance of irrigation infrastructure, leading to an overall reduction of the agricultural livelihoods in the community (Parveen et al., 2015 <sup>[[#fn:r1024|1024]]</sup> ).

In addition to affecting pastoral transhumance and increasing wage labour migration, cryosphere changes impact human mobility by creating cases of displacement. These cases differ from wage labour migration because they involve entire communities. As a result, they are irreversible, unlike cases in which individuals undertake long-term or permanent migration from their communities but retain the possibility of returning, because, for example, some relatives or former neighbours have remained in place. In this way, these cases of displacement represent cryosphere driven challenges to habitability. Though natural hazards have historically led some communities to relocate, cryosphere changes have contributed to instances of displacement. Unreliable water availability and increased risks of natural hazards are responsible for resettlement of villages in certain high mountain areas (McDonald, 1989 <sup>[[#fn:r1025|1025]]</sup> ; Parveen et al., 2015 <sup>[[#fn:r1026|1026]]</sup> ). A village in Western Nepal moved to lower elevation after decreasing snowfall reduced the flow of water in the river on which their pastoralism and agriculture depended (Barnett et al., 2005 <sup>[[#fn:r1027|1027]]</sup> ). Three villages in Nepal faced severe declines in agricultural and pastoral livelihoods because decreased snow cover led to reduced soil moisture and to the drying up of springs, which were the historical source of irrigation water; in conjunction with an international non-governmental organisation (INGO), the residents planned a move to a lower area (Prasain, 2018 <sup>[[#fn:r1028|1028]]</sup> ).

The issue of habitability arises in the cases, mentioned above, of communities that relocate after floods or debris flows destroy houses and irrigation infrastructure, or damage fields and pastures. It occurs as well in the cases of households with extensive long-term migration, where agricultural and pastoral livelihoods are undermined by reduced water supply caused by cryospheric change (Barnett et al., 2005 <sup>[[#fn:r1029|1029]]</sup> ). In addition, the loss of cultural values, including spiritual and intrinsic values (Section 2.3.6), can contribute to decisions to migrate (Kaenzig, 2015 <sup>[[#fn:r1030|1030]]</sup> ). Combined with the patterns of permanent emigration, this issue of habitability raises the issue of limits to adaptation in mountain areas (Huggel et al., 2019 <sup>[[#fn:r1031|1031]]</sup> ). Projections of decreased streamflow by 2100 in watersheds with strong glacier melt water components in Asia, Europe, and North and South America (Section 2.3.1.1) indicate that threats to habitability may continue through this period and affect the endeavours of achieving the SDGs in developing countries (Rasul et al., 2019 <sup>[[#fn:r1032|1032]]</sup> ).

<span id="international-policy-frameworks-and-pathways-to-sustainable-development"></span>