IPCC:AR6/SROCC/Chapter-3 - Revision history

Laura: /* Supplementary Material */

2026-06-01T07:03:30Z

Supplementary Material

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	To view the Supplementary Material for Chapter 3 click on the image below		To view the Supplementary Material for Chapter 3 click on the image below

	<!-- START SM IMG -->		<!-- START SM IMG -->
	[https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/SROCC_Ch03-SM_FINAL.pdf [[File:511044bd972750967794fb259aa603d6 SROCC-Ch3-SM-Cover.jpg]]]		[https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/SROCC_Ch03-SM_FINAL.pdf [[File:511044bd972750967794fb259aa603d6 SROCC-Ch3-SM-Cover.jpg\|200px]]]

	<!-- END IMG -->		<!-- END IMG -->

Laura: /* Box 3.4 Impacts and Risks for Polar Biodiversity from Range Shifts and Species Invasions Related to Climate Change */

2026-06-01T07:02:40Z

Box 3.4 Impacts and Risks for Polar Biodiversity from Range Shifts and Species Invasions Related to Climate Change

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	<span id="spatial-distribution-of-fish-communities-identified-at-bottom-trawl-stations-in-the-barents-sea-north-of-northern-norway-and-russia-position-indicated-by-red-box-in-small-globe-in-a-2004-and-b-2012.-atlantic-red-arctic-blue-and-central-communities-yellow.-circles-shallow-sub-communities-triangles-deep-sub-communities.-modified-from-fossheim-et-al.-2015."></span>		<span id="spatial-distribution-of-fish-communities-identified-at-bottom-trawl-stations-in-the-barents-sea-north-of-northern-norway-and-russia-position-indicated-by-red-box-in-small-globe-in-a-2004-and-b-2012.-atlantic-red-arctic-blue-and-central-communities-yellow.-circles-shallow-sub-communities-triangles-deep-sub-communities.-modified-from-fossheim-et-al.-2015."></span>

	<!-- IMG CAPTION -->		<!-- IMG CAPTION -->
	'''Spatial distribution of fish communities identified at bottom trawl stations in the Barents Sea (north of northern Norway and Russia, position indicated by red box in small globe) in (a) 2004 and (b) 2012. Atlantic (red), Arctic (blue) and Central communities (yellow). Circles: shallow sub-communities, triangles: deep sub-communities. Modified from Fossheim et al. (2015).'''		'''Spatial distribution of fish communities identified at bottom trawl stations in the Barents Sea (north of northern Norway and Russia, position indicated by red box in small globe) in (a) 2004 and (b) 2012. Atlantic (red), Arctic (blue) and Central communities (yellow). Circles: shallow sub-communities, triangles: deep sub-communities. Modified from Fossheim et al. (2015).'''

	<!-- IMG FILE -->		<!-- IMG FILE -->
	[[File:d730cedc393bc8b382a6b48540e95cbd IPCC-SROCC-CH_3_Box3_4.jpg]]		[[File:d730cedc393bc8b382a6b48540e95cbd IPCC-SROCC-CH_3_Box3_4.jpg]]
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	Alien species are a major driver of terrestrial biodiversity change also in the Antarctic region (Frenot et al., 2005<sup>[[#fn:r1814\|1814]]</sup>; Chown et al., 2012<sup>[[#fn:r1815\|1815]]</sup>; McClelland et al., 2017<sup>[[#fn:r1816\|1816]]</sup>). The Protocol on Environmental Protection to the Antarctic Treaty restricts the introduction of non-native species to Antarctica as do the management authorities of sub-Antarctic islands (De Villiers et al., 2006). Despite this, alien species and their propagules continue to be introduced to the Antarctic continent and sub-Antarctic islands (Hughes et al., 2015<sup>[[#fn:r1817\|1817]]</sup>). To date, 14 non-native terrestrial species have colonised the Antarctic Treaty area (excluding sub-Antarctic islands) (Hughes et al., 2015<sup>[[#fn:r1818\|1818]]</sup>), while the number in the sub-Antarctic is much higher (on the order of 200 species) (Frenot et al., 2005<sup>[[#fn:r1819\|1819]]</sup>) (''low confidence''). Species distribution models for terrestrial invasive species indicate that climate does not currently constitute a barrier for the establishment of invasive species on all subantarctic islands, and that the AP region will be the most vulnerable location on the Antarctic continent to invasive species establishment under RCP8.5 (Duffy et al., 2017<sup>[[#fn:r1820\|1820]]</sup>). Thus, for continental Antarctica, existing climatic barriers to alien species establishment will weaken as warming continues across the region (''medium confidence''). An increase in the ice-free area linked to glacier retreat in Antarctica is expected to increase the area available for new terrestrial ecosystems (Lee et al., 2017a<sup>[[#fn:r1821\|1821]]</sup>). Along with growing number of visitors, this is expected to increase in the establishment probability of terrestrial alien species (Chown et al., 2012<sup>[[#fn:r1822\|1822]]</sup>; Hughes et al., 2015<sup>[[#fn:r1823\|1823]]</sup>) (''medium confidence'').		Alien species are a major driver of terrestrial biodiversity change also in the Antarctic region (Frenot et al., 2005<sup>[[#fn:r1814\|1814]]</sup>; Chown et al., 2012<sup>[[#fn:r1815\|1815]]</sup>; McClelland et al., 2017<sup>[[#fn:r1816\|1816]]</sup>). The Protocol on Environmental Protection to the Antarctic Treaty restricts the introduction of non-native species to Antarctica as do the management authorities of sub-Antarctic islands (De Villiers et al., 2006). Despite this, alien species and their propagules continue to be introduced to the Antarctic continent and sub-Antarctic islands (Hughes et al., 2015<sup>[[#fn:r1817\|1817]]</sup>). To date, 14 non-native terrestrial species have colonised the Antarctic Treaty area (excluding sub-Antarctic islands) (Hughes et al., 2015<sup>[[#fn:r1818\|1818]]</sup>), while the number in the sub-Antarctic is much higher (on the order of 200 species) (Frenot et al., 2005<sup>[[#fn:r1819\|1819]]</sup>) (''low confidence''). Species distribution models for terrestrial invasive species indicate that climate does not currently constitute a barrier for the establishment of invasive species on all subantarctic islands, and that the AP region will be the most vulnerable location on the Antarctic continent to invasive species establishment under RCP8.5 (Duffy et al., 2017<sup>[[#fn:r1820\|1820]]</sup>). Thus, for continental Antarctica, existing climatic barriers to alien species establishment will weaken as warming continues across the region (''medium confidence''). An increase in the ice-free area linked to glacier retreat in Antarctica is expected to increase the area available for new terrestrial ecosystems (Lee et al., 2017a<sup>[[#fn:r1821\|1821]]</sup>). Along with growing number of visitors, this is expected to increase in the establishment probability of terrestrial alien species (Chown et al., 2012<sup>[[#fn:r1822\|1822]]</sup>; Hughes et al., 2015<sup>[[#fn:r1823\|1823]]</sup>) (''medium confidence'').
			</div>
	<div id="section-3-4-3-3-impacts-on-social-ecological-systems"></div>		<div id="section-3-4-3-3-impacts-on-social-ecological-systems"></div>

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	<span id="human-responses-to-climate-change-in-polar-regions"></span>		<span id="human-responses-to-climate-change-in-polar-regions"></span>

	== 3.5 Human Responses to Climate Change in Polar Regions ==		== 3.5 Human Responses to Climate Change in Polar Regions ==

Laura: /* 3.4.3.2.3 Freshwater */

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3.4.3.2.3 Freshwater

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	<span id="box-3.4-impacts-and-risks-for-polar-biodiversity-from-range-shifts-and-species-invasions-related-to-climate-change"></span>		<span id="box-3.4-impacts-and-risks-for-polar-biodiversity-from-range-shifts-and-species-invasions-related-to-climate-change"></span>
			<div class="container-box col-regular">

	== Box 3.4 Impacts and Risks for Polar Biodiversity from Range Shifts and Species Invasions Related to Climate Change ==		== Box 3.4 Impacts and Risks for Polar Biodiversity from Range Shifts and Species Invasions Related to Climate Change ==

Laura: /* CCB.8 Future Sea Level Changes and Marine Ice Sheet Instability */

2026-06-01T07:01:38Z

CCB.8 Future Sea Level Changes and Marine Ice Sheet Instability

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	Overall, this assessment finds that unstable retreat and thinning of some Antarctic glaciers, and to a lesser extent Greenland outlet glaciers, may be underway. However, the timescale and future rate of these processes is not well known, casting deep uncertainty on projections of the sea level contributions from the AIS (Cross-Chapter Box 5 in Chapter 1, Section 4.2.3.1).		Overall, this assessment finds that unstable retreat and thinning of some Antarctic glaciers, and to a lesser extent Greenland outlet glaciers, may be underway. However, the timescale and future rate of these processes is not well known, casting deep uncertainty on projections of the sea level contributions from the AIS (Cross-Chapter Box 5 in Chapter 1, Section 4.2.3.1).
			</div>
			<span id="arctic-snow-freshwater-ice-and-permafrost-changes-consequences-and-impacts"></span>

	~~<span id="arctic-snow-freshwater-ice-and-permafrost-changes-consequences-and-impacts"></span>~~
	== 3.4 Arctic Snow, Freshwater Ice and Permafrost: Changes, Consequences and Impacts ==		== 3.4 Arctic Snow, Freshwater Ice and Permafrost: Changes, Consequences and Impacts ==

Laura: /* 3.3.3.4 Ecosystems */

2026-06-01T07:01:21Z

3.3.3.4 Ecosystems

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	<span id="ccb.8-future-sea-level-changes-and-marine-ice-sheet-instability"></span>		<span id="ccb.8-future-sea-level-changes-and-marine-ice-sheet-instability"></span>
			<div class="container-box col-cross">

	== CCB.8 Future Sea Level Changes and Marine Ice Sheet Instability ==		== CCB.8 Future Sea Level Changes and Marine Ice Sheet Instability ==

Laura: /* 3.2.2.3 Carbon and Ocean Acidification */

2026-06-01T07:00:27Z

3.2.2.3 Carbon and Ocean Acidification

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	<span id="the-upper-ocean-010-m-at-end-of-this-century-20812100-characterised-by-undersaturated-conditions-for-aragonite-across-90-confidence-intervals-dark-red-to-light-red-for-the-representative-concentration-pathway-rcp8.5-a-and-rcp2.6-b-scenarios-in-the-coupled-model-intercomparison-project-phase-5-cmip5.-saturation-states-are-averaged-and-confidence-intervals-calculated-at"></span>		<span id="the-upper-ocean-010-m-at-end-of-this-century-20812100-characterised-by-undersaturated-conditions-for-aragonite-across-90-confidence-intervals-dark-red-to-light-red-for-the-representative-concentration-pathway-rcp8.5-a-and-rcp2.6-b-scenarios-in-the-coupled-model-intercomparison-project-phase-5-cmip5.-saturation-states-are-averaged-and-confidence-intervals-calculated-at"></span>

	<!-- IMG CAPTION -->		<!-- IMG CAPTION -->
	'''The upper ocean (0–10 m) at end of this century (2081–2100), characterised by undersaturated conditions for aragonite across 90% confidence intervals (dark red to light red) for the Representative Concentration Pathway (RCP)8.5 (a) and RCP2.6 (b) scenarios in the Coupled Model Intercomparison Project Phase 5 (CMIP5). Saturation states are averaged and confidence intervals calculated at […]'''		'''The upper ocean (0–10 m) at end of this century (2081–2100), characterised by undersaturated conditions for aragonite across 90% confidence intervals (dark red to light red) for the Representative Concentration Pathway (RCP)8.5 (a) and RCP2.6 (b) scenarios in the Coupled Model Intercomparison Project Phase 5 (CMIP5). Saturation states are averaged and confidence intervals calculated at […]'''

	<!-- IMG FILE -->		<!-- IMG FILE -->
	[[File:c8a10b7483d8fc1fc700af74963ecd68 IPCC-SROCC-CH_3_4.jpg]]		[[File:c8a10b7483d8fc1fc700af74963ecd68 IPCC-SROCC-CH_3_4.jpg]]
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	<span id="impacts-on-marine-ecosystems"></span>		<span id="impacts-on-marine-ecosystems"></span>

	=== 3.2.3 Impacts on Marine Ecosystems ===		=== 3.2.3 Impacts on Marine Ecosystems ===

Laura: /* Box 3.3 Polynyas */

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Box 3.3 Polynyas

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	In some CMIP5 models, phases of Weddell polynya activity appear for decades or centuries at a time, and then cease for a similar period (Reintges et al., 2017<sup>[[#fn:r482\|482]]</sup>). The observational era is not sufficiently long to rule out this behaviour. Models indicate that under anthropogenic climate change, surface freshening caused by increased precipitation reduces the occurrence of the Weddell polynya (de Lavergne et al., 2014). There are systematic biases in modelled ocean stratification resulting in ''low confidence'' in future Weddell Polynya projections (Reintges et al., 2017<sup>[[#fn:r483\|483]]</sup>).		In some CMIP5 models, phases of Weddell polynya activity appear for decades or centuries at a time, and then cease for a similar period (Reintges et al., 2017<sup>[[#fn:r482\|482]]</sup>). The observational era is not sufficiently long to rule out this behaviour. Models indicate that under anthropogenic climate change, surface freshening caused by increased precipitation reduces the occurrence of the Weddell polynya (de Lavergne et al., 2014). There are systematic biases in modelled ocean stratification resulting in ''low confidence'' in future Weddell Polynya projections (Reintges et al., 2017<sup>[[#fn:r483\|483]]</sup>).
			</div>
	<div id="section-3-2-2-2-physical-oceanography"></div>		<div id="section-3-2-2-2-physical-oceanography"></div>

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	<span id="polar-ice-sheets-and-glaciers-changes-consequences-and-impacts"></span>		<span id="polar-ice-sheets-and-glaciers-changes-consequences-and-impacts"></span>

	== 3.3 Polar Ice Sheets and Glaciers: Changes, Consequences and Impacts ==		== 3.3 Polar Ice Sheets and Glaciers: Changes, Consequences and Impacts ==

Laura: /* 3.2.2.1 Sea Ice */

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3.2.2.1 Sea Ice

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	<span id="box-3.3-polynyas"></span>		<span id="box-3.3-polynyas"></span>
			<div class="container-box col-regular">

	== Box 3.3 Polynyas ==		== Box 3.3 Polynyas ==

Laura: /* CCB.7 Southern Ocean Circulation: Drivers, Changes and Implications */

2026-06-01T06:59:16Z

CCB.7 Southern Ocean Circulation: Drivers, Changes and Implications

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	The considerable Coupled Model Intercomparison Project Phase 5 (CMIP5) inter-model variations in Southern Ocean time-mean circulation projections reported in WGI AR5 (Meijers et al., 2012<sup>[[#fn:r361\|361]]</sup>; Downes and Hogg, 2013<sup>[[#fn:r362\|362]]</sup>) remain largely unchanged. Some of the differences in projected changes have been found to be correlated with biases in the various models’ ability to simulate the historical state of the Southern Ocean, such as mixed layer depth (Sallée et al., 2013a<sup>[[#fn:r363\|363]]</sup>) and westerly wind jet latitude (Bracegirdle et al., 2013<sup>[[#fn:r364\|364]]</sup>). This suggests that bias reduction against observed historical metrics (Russell et al., 2018<sup>[[#fn:r365\|365]]</sup>) in future generations of coupled models (e.g., Coupled Model Intercomparison Project Phase 6 (CMIP6)) should lead to improved confidence in aspects of projected Southern Ocean changes. CMIP5 models suggest that the subduction of mode and intermediate water will increase (Sallée et al., 2013b<sup>[[#fn:r366\|366]]</sup>), which will affect oxygen and nutrient transports, and the overall transport of the Southern Ocean upper overturning cell will increase by up to 20% (Downes and Hogg, 2013<sup>[[#fn:r367\|367]]</sup>), but model performance is limited by the inability to explicitly resolve eddy processes (Gent, 2016<sup>[[#fn:r368\|368]]</sup>; Downes et al., 2018<sup>[[#fn:r369\|369]]</sup>). The formation and export of Antarctic Bottom Water is predicted to continue decreasing (Heuzé et al., 2015<sup>[[#fn:r370\|370]]</sup>) due to warming and freshening of surface source waters near the continent. These are, however, some of the most poorly represented processes in global models. Further uncertainty derives from increased meltwater from the AIS not being considered in the CMIP5 climate models, despite its potential for significant impact on Southern Ocean dynamics and the global climate, and its potential for positive feedbacks (Bronselaer et al., 2018<sup>[[#fn:r371\|371]]</sup>). Due to these uncertainties, ''low confidence'' is therefore ascribed to the CMIP5-based model projections of future Southern Ocean circulation and water masses.		The considerable Coupled Model Intercomparison Project Phase 5 (CMIP5) inter-model variations in Southern Ocean time-mean circulation projections reported in WGI AR5 (Meijers et al., 2012<sup>[[#fn:r361\|361]]</sup>; Downes and Hogg, 2013<sup>[[#fn:r362\|362]]</sup>) remain largely unchanged. Some of the differences in projected changes have been found to be correlated with biases in the various models’ ability to simulate the historical state of the Southern Ocean, such as mixed layer depth (Sallée et al., 2013a<sup>[[#fn:r363\|363]]</sup>) and westerly wind jet latitude (Bracegirdle et al., 2013<sup>[[#fn:r364\|364]]</sup>). This suggests that bias reduction against observed historical metrics (Russell et al., 2018<sup>[[#fn:r365\|365]]</sup>) in future generations of coupled models (e.g., Coupled Model Intercomparison Project Phase 6 (CMIP6)) should lead to improved confidence in aspects of projected Southern Ocean changes. CMIP5 models suggest that the subduction of mode and intermediate water will increase (Sallée et al., 2013b<sup>[[#fn:r366\|366]]</sup>), which will affect oxygen and nutrient transports, and the overall transport of the Southern Ocean upper overturning cell will increase by up to 20% (Downes and Hogg, 2013<sup>[[#fn:r367\|367]]</sup>), but model performance is limited by the inability to explicitly resolve eddy processes (Gent, 2016<sup>[[#fn:r368\|368]]</sup>; Downes et al., 2018<sup>[[#fn:r369\|369]]</sup>). The formation and export of Antarctic Bottom Water is predicted to continue decreasing (Heuzé et al., 2015<sup>[[#fn:r370\|370]]</sup>) due to warming and freshening of surface source waters near the continent. These are, however, some of the most poorly represented processes in global models. Further uncertainty derives from increased meltwater from the AIS not being considered in the CMIP5 climate models, despite its potential for significant impact on Southern Ocean dynamics and the global climate, and its potential for positive feedbacks (Bronselaer et al., 2018<sup>[[#fn:r371\|371]]</sup>). Due to these uncertainties, ''low confidence'' is therefore ascribed to the CMIP5-based model projections of future Southern Ocean circulation and water masses.
			</div>
	<span id="projected-changes-in-sea-ice-and-ocean"></span>		<span id="projected-changes-in-sea-ice-and-ocean"></span>
	=== 3.2.2 Projected Changes in Sea Ice and Ocean ===		=== 3.2.2 Projected Changes in Sea Ice and Ocean ===
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	<span id="box-3.3-polynyas"></span>		<span id="box-3.3-polynyas"></span>

	== Box 3.3 Polynyas ==		== Box 3.3 Polynyas ==

Laura: /* 3.2.1.3 Ocean Circulation */

2026-06-01T06:58:53Z

3.2.1.3 Ocean Circulation

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	<span id="ccb.7-southern-ocean-circulation-drivers-changes-and-implications"></span>		<span id="ccb.7-southern-ocean-circulation-drivers-changes-and-implications"></span>
			<div class="container-box col-cross">

	== CCB.7 Southern Ocean Circulation: Drivers, Changes and Implications ==		== CCB.7 Southern Ocean Circulation: Drivers, Changes and Implications ==