IPCC:AR6/SROCC/Chapter-2 - Revision history

Laura: /* Supplementary Material */

2026-06-01T06:54:15Z

Supplementary Material

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	To view the Supplementary Material for Chapter 2 click on the image below		To view the Supplementary Material for Chapter 2 click on the image below

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	[https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/SROCC_Ch02-SM_FINAL.pdf [[File:d4de0eb281331fb86c3fb0d4e6495dcb SROCC-Ch2-SM-Cover.jpg]]]		[https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/SROCC_Ch02-SM_FINAL.pdf [[File:d4de0eb281331fb86c3fb0d4e6495dcb SROCC-Ch2-SM-Cover.jpg\|200px]]]

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Laura: /* A.2.A Additional Information on Global and Regional Glacier Mass Change Estimates for 2006–2015 */

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A.2.A Additional Information on Global and Regional Glacier Mass Change Estimates for 2006–2015

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	'''Table 2A.1'''		'''Table 2A.1'''


	'''Table 2A.1''' . Regional estimates of glacier mass budget in three different units. Only estimates from the studies marked in bold were used to derive the average SROCC estimates. Regional glacier area ''A'' and volume ''V'' are taken from the Randolph Glacier Inventory (RGI Consortium, 2017) and Farinotti et al. (2019), respectively. Method ''geod'' . refers to the geodetic method (using elevation changes) and ''gl'' . refers to the glaciological method (based on in-situ mass-balance observations). Results are given for various aggregated areas including among others all regions combined (global), and global excluding the Antarctic (A) and Greenland (G) periphery. All regional estimates (in kg m -2 yr -1) are shown in Figures 2.4 and 3.8). SLE is sea level equivalent.		'''Table 2A.1''' . Regional estimates of glacier mass budget in three different units. Only estimates from the studies marked in bold were used to derive the average SROCC estimates. Regional glacier area ''A'' and volume ''V'' are taken from the Randolph Glacier Inventory (RGI Consortium, 2017) and Farinotti et al. (2019), respectively. Method ''geod'' . refers to the geodetic method (using elevation changes) and ''gl'' . refers to the glaciological method (based on in-situ mass-balance observations). Results are given for various aggregated areas including among others all regions combined (global), and global excluding the Antarctic (A) and Greenland (G) periphery. All regional estimates (in kg m -2 yr -1) are shown in Figures 2.4 and 3.8). SLE is sea level equivalent.
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	<span id="c-citation"></span>		<span id="c-citation"></span>

	== Acknowledgements ==		== Acknowledgements ==

Laura: /* 2.3.3.2 Freshwater Biota */

2026-06-01T06:53:13Z

2.3.3.2 Freshwater Biota

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

	<span id="ecosystem-services-and-adaptation"></span>		<span id="ecosystem-services-and-adaptation"></span>

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

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

2026-06-01T06:52:46Z

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

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

	== 2.4 International Policy Frameworks and Pathways to Sustainable Development ==		== 2.4 International Policy Frameworks and Pathways to Sustainable Development ==

Laura: /* 2.3.2.3 Disaster Risk Reduction and Adaptation */

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2.3.2.3 Disaster Risk Reduction and Adaptation

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	<span id="box-2.4-challenges-to-farmers-and-local-population-related-to-shrinkages-in-the-cryosphere-cordillera-blanca-peru"></span>		<span id="box-2.4-challenges-to-farmers-and-local-population-related-to-shrinkages-in-the-cryosphere-cordillera-blanca-peru"></span>
			<div class="container-box col-regular">

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

Laura: /* Box 2.3 Local Responses to Water Shortage in northwest India */

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Box 2.3 Local Responses to Water Shortage in northwest India

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	<div id="section-2-3-1-3key-impacts-and-vulnerability-block-4">		<div id="section-2-3-1-3key-impacts-and-vulnerability-block-4">
	</div>		</div>
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	<span id="box-2.4-challenges-to-farmers-and-local-population-related-to-shrinkages-in-the-cryosphere-cordillera-blanca-peru"></span>		<span id="box-2.4-challenges-to-farmers-and-local-population-related-to-shrinkages-in-the-cryosphere-cordillera-blanca-peru"></span>

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

Laura: /* 2.3.1.3.2 Agriculture */

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2.3.1.3.2 Agriculture

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	<span id="box-2.3-local-responses-to-water-shortage-in-northwest-india"></span>		<span id="box-2.3-local-responses-to-water-shortage-in-northwest-india"></span>
			<div class="container-box col-regular">

	== Box 2.3 Local Responses to Water Shortage in northwest India ==		== Box 2.3 Local Responses to Water Shortage in northwest India ==

Laura: /* Box 2.2 Local, Regional and Global Climate Feedbacks Involving the Mountain Cryosphere */

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Box 2.2 Local, Regional and Global Climate Feedbacks Involving the Mountain Cryosphere

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	Global-scale climate feedbacks from the cryosphere remain largely unexplored with respect to the proportion originating from high mountains. Although mountain topography affects global climate (e.g., Naiman et al., 2017), there is little evidence for mountain-cryosphere specific feedbacks, largely because of the limited spatial extent of the mountain cryosphere. The most relevant feedback probably relates to permafrost in mountains, which contain about 28% of the global permafrost area (Section 2.2.4). Organic carbon stored in permafrost can be decayed following thaw and transferred to the atmosphere as carbon dioxide or methane (Schuur et al., 2015<sup>[[#fn:r226\|226]]</sup>). This self-reinforcing effect accelerates the pace of climate change and operates in polar (Section 3.4.1.2.3) and mountain areas alike (Mu et al., 2017<sup>[[#fn:r227\|227]]</sup>; Sun et al., 2018a<sup>[[#fn:r228\|228]]</sup>). In contrast to polar areas, however, there is ''limited evidence'' and ''low agreement'' on the total amount of permafrost carbon in mountains because of differences in upscaling and difficulties to distinguish permafrost and seasonally frozen soils due to the lack of data. For example, on the Tibetan Plateau, the top 3 m of permafrost are estimated to contain about 15 petagrams (Ding et al., 2016<sup>[[#fn:r229\|229]]</sup>) and mountain soils with permafrost globally are estimated to contain approximately 66 petagrams of organic carbon (Bockheim and Munroe, 2014<sup>[[#fn:r230\|230]]</sup>). At the same time, there is ''limited evidence'' and ''high agreement'' that the average density (kg C m -2) of permafrost carbon in mountains is lower than in other areas. For example, densities of soil organic carbon are low in the sub-arctic Ural (Dymov et al., 2015<sup>[[#fn:r231\|231]]</sup>) and 1–2 orders of magnitude lower in subarctic Sweden (Fuchs et al., 2015<sup>[[#fn:r232\|232]]</sup>) in comparison to lowland permafrost, and 50% lower in mountains than in steppe-tundra in Siberia and Alaska (Zimov et al., 2006<sup>[[#fn:r233\|233]]</sup>). Some mechanisms of soil carbon decay and transfer to the atmosphere in mountains are similar to those in lowland areas, for example collapse following thaw in peatlands (Mu et al., 2016<sup>[[#fn:r234\|234]]</sup>; Mamet et al., 2017<sup>[[#fn:r235\|235]]</sup>), and some are specific to areas with steep slopes, for example drainage of water from thawing permafrost leading to soil aeration (Dymov et al., 2015<sup>[[#fn:r236\|236]]</sup>). There is no global-scale analysis of the climate feedback from permafrost in mountains. Given that projections indicate increasing thaw and degradation of permafrost in mountains during the 21st century (''very'' ''high confidence'') (Section 2.2.4), a corresponding increase in greenhouse gas emissions can be anticipated but is not quantified.		Global-scale climate feedbacks from the cryosphere remain largely unexplored with respect to the proportion originating from high mountains. Although mountain topography affects global climate (e.g., Naiman et al., 2017), there is little evidence for mountain-cryosphere specific feedbacks, largely because of the limited spatial extent of the mountain cryosphere. The most relevant feedback probably relates to permafrost in mountains, which contain about 28% of the global permafrost area (Section 2.2.4). Organic carbon stored in permafrost can be decayed following thaw and transferred to the atmosphere as carbon dioxide or methane (Schuur et al., 2015<sup>[[#fn:r226\|226]]</sup>). This self-reinforcing effect accelerates the pace of climate change and operates in polar (Section 3.4.1.2.3) and mountain areas alike (Mu et al., 2017<sup>[[#fn:r227\|227]]</sup>; Sun et al., 2018a<sup>[[#fn:r228\|228]]</sup>). In contrast to polar areas, however, there is ''limited evidence'' and ''low agreement'' on the total amount of permafrost carbon in mountains because of differences in upscaling and difficulties to distinguish permafrost and seasonally frozen soils due to the lack of data. For example, on the Tibetan Plateau, the top 3 m of permafrost are estimated to contain about 15 petagrams (Ding et al., 2016<sup>[[#fn:r229\|229]]</sup>) and mountain soils with permafrost globally are estimated to contain approximately 66 petagrams of organic carbon (Bockheim and Munroe, 2014<sup>[[#fn:r230\|230]]</sup>). At the same time, there is ''limited evidence'' and ''high agreement'' that the average density (kg C m -2) of permafrost carbon in mountains is lower than in other areas. For example, densities of soil organic carbon are low in the sub-arctic Ural (Dymov et al., 2015<sup>[[#fn:r231\|231]]</sup>) and 1–2 orders of magnitude lower in subarctic Sweden (Fuchs et al., 2015<sup>[[#fn:r232\|232]]</sup>) in comparison to lowland permafrost, and 50% lower in mountains than in steppe-tundra in Siberia and Alaska (Zimov et al., 2006<sup>[[#fn:r233\|233]]</sup>). Some mechanisms of soil carbon decay and transfer to the atmosphere in mountains are similar to those in lowland areas, for example collapse following thaw in peatlands (Mu et al., 2016<sup>[[#fn:r234\|234]]</sup>; Mamet et al., 2017<sup>[[#fn:r235\|235]]</sup>), and some are specific to areas with steep slopes, for example drainage of water from thawing permafrost leading to soil aeration (Dymov et al., 2015<sup>[[#fn:r236\|236]]</sup>). There is no global-scale analysis of the climate feedback from permafrost in mountains. Given that projections indicate increasing thaw and degradation of permafrost in mountains during the 21st century (''very'' ''high confidence'') (Section 2.2.4), a corresponding increase in greenhouse gas emissions can be anticipated but is not quantified.
			</div>
			<span id="mountain-social-ecological-systems-impacts-risks-and-human-responses"></span>

	~~<span id="mountain-social-ecological-systems-impacts-risks-and-human-responses"></span>~~
	== 2.3 Mountain Social-Ecological Systems: Impacts, Risks and Human Responses ==		== 2.3 Mountain Social-Ecological Systems: Impacts, Risks and Human Responses ==

Laura: /* 2.2.5 Lake and River Ice */

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2.2.5 Lake and River Ice

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	<span id="box-2.2-local-regional-and-global-climate-feedbacks-involving-the-mountain-cryosphere"></span>		<span id="box-2.2-local-regional-and-global-climate-feedbacks-involving-the-mountain-cryosphere"></span>
			<div class="container-box col-regular">

	== Box 2.2 Local, Regional and Global Climate Feedbacks Involving the Mountain Cryosphere ==		== Box 2.2 Local, Regional and Global Climate Feedbacks Involving the Mountain Cryosphere ==

Laura: /* CCB.6 Glacier Projections in Polar and High Mountain Regions */

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CCB.6 Glacier Projections in Polar and High Mountain Regions

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	<span id="box-2.2-local-regional-and-global-climate-feedbacks-involving-the-mountain-cryosphere"></span>		<span id="box-2.2-local-regional-and-global-climate-feedbacks-involving-the-mountain-cryosphere"></span>

	== Box 2.2 Local, Regional and Global Climate Feedbacks Involving the Mountain Cryosphere ==		== Box 2.2 Local, Regional and Global Climate Feedbacks Involving the Mountain Cryosphere ==