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

==== 2.3.3.3 Ecosystem Services and Adaptation ====

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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'' ).

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