Editing IPCC:AR6/WGII/Cross-Chapter-Paper-6 (section)

== CCP6.2 Observed Impacts and Future Risks ==

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=== CCP6.2.1 Marine and Coastal Ecosystems ===

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==== CCP6.2.1.1 Warming and sea ice retreat cause shifts in distribution ranges of species ====

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In Arctic seas, warming and other climate impact drivers, primarily sea ice retreat, have led to range contractions of Arctic marine and ice-associated species and poleward expansions of boreal species ( ''very high confidence'' ) (Table CCP6.2) ( [[#Bouchard--2020|Bouchard and Fortier, 2020]] ; [[#Huntington--2020|Huntington et al., 2020]] ; [[#Mueter--2020|Mueter et al., 2020]] ) even though light and energetics at seasonal extremes may limit some range shifts ( ''limited evidence'' ) ( [[#Ljungström--2021|Ljungström et al., 2021]] ). Altered conditions allow more microorganisms to move poleward and provide opportunities for invasive species ( [[#Cavicchioli--2019|Cavicchioli et al., 2019]] ; [[#Nielsen--2020|Nielsen et al., 2020]] ; Mustonen, 2021). Phytoplankton communities harbour increasing numbers of taxa, including harmful species ( [[#Lovejoy--2017|Lovejoy et al., 2017]] ) and the coccolithophore ''Emiliania huxleyi'' , which meanwhile forms regular blooms in the Barents Sea ( [[#Neukermans--2018|Neukermans et al., 2018]] ; [[#Silkin--2020|Silkin et al., 2020]] ). Northward shifts of pelagic, benthic and demersal species and subsequent changes in Arctic community composition have been observed in the Bering, Greenland and Barents Seas ( [[#Grebmeier--2018|Grebmeier et al., 2018]] ; [[#Mueter--2020|Mueter et al., 2020]] ), as have higher numbers of economically important boreal species such as haddock and Pacific and Atlantic cod (CCP6.2.3). Cold-adapted Arctic fish species such as polar cod ( ''Boreogadus saida'' ) are expected to decline further and lose spawning habitats at GWL &gt;1.5°C, mainly due to a lack of phenotypic plasticity, as well as increasing interspecific competition with and predation from invading boreal species ( [[#Dahlke--2018|Dahlke et al., 2018]] ; [[#Marsh--2020|Marsh and Mueter, 2020]] ). Numerous mammals and sea birds respond to changes in the distribution of their preferred habitats and prey by shifting their range, altering the timing or pathways for migration or switching prey ( ''very high confidence'' ) ( [[#Hamilton--2017|Hamilton et al., 2017]] ; [[#Loseto--2018|Loseto et al., 2018]] ; [[#Meredith--2019|Meredith et al., 2019]] ). Ice-breeding seals (e.g., harp seals – ''Pagophilus groenlandicus'' ) often have little scope to shift distribution, leading to increases in strandings and pup mortality in years with little ice cover ( ''medium confidence'' ) (Table CCP6.2) ( [[#Boveng--2020|Boveng et al., 2020]] ). Recent studies confirm that polar bears ( ''Ursus maritimus'' ) are negatively affected by changing ice and snow conditions with decreases in denning, foraging, reproduction, genetic diversity and survival rates ( ''very high confidence'' ) (Table CCP6.2) ( [[#Boonstra--2020|Boonstra et al., 2020]] ; [[#Johnson--2020|Johnson and Derocher, 2020]] ; [[#Maduna--2021|Maduna et al., 2021]] ).

In the Southern Ocean, southward range shifts are expected to result from increased warming coupled with the narrow thermal tolerance of cold-adapted Antarctic species ( [[#Convey--2019|Convey and Peck, 2019]] ; [[#Morley--2019|Morley et al., 2019]] ; [[#Gutt--2021|Gutt et al., 2021]] ). Such shifts have so far only been detected for Antarctic krill ( ''Euphausia superba'' ), with a poleward contraction of the highest densities of krill in the Atlantic sector ( ''medium confidence'' ) (Table CCP6.2); ( [[#Atkinson--2019|Atkinson et al., 2019]] ). Ocean warming is expected to put pressure on Antarctic phytoplankton ( [[#Pinkerton--2021|Pinkerton et al., 2021]] ) and fish species unable to move further south in shelf areas, including waters off sub-Antarctic islands ( ''low confidence'' ) (Table CCP6.2) ( [[#Caccavo--2021|Caccavo et al., 2021]] ). Off the Antarctic Peninsula and sub-Antarctic islands, invasive benthic invertebrates and macroalgae have already been detected ( ''medium confidence'' ) ( [[#Fraser--2018|Fraser et al., 2018]] ; [[#Avila--2020|Avila et al., 2020]] ; [[#Brasier--2021|Brasier et al., 2021]] ), and projected changes will further favour the spread of invasive species ( [[#Fraser--2020|Fraser et al., 2020]] ; [[#Macaya--2020|Macaya et al., 2020]] ). On a local to regional scale, the benthic recolonisation of the newly exposed seabed after the disintegration of ice shelves shows typical succession patterns, with mass occurrences of few pioneer species followed by gradual shifts to a more diverse typical shelf community, driven by increasing pelagic primary production upon ice-shelf collapse and strengthening of the pelagic–benthic coupling ( ''high confidence'' ) ( [[#Brasier--2021|Brasier et al., 2021]] ; [[#Gutt--2021|Gutt et al., 2021]] ). Range changes of Antarctic birds and marine mammals have been observed, which vary among sub-regions and are mostly attributable to changes in sea ice extent and food availability ( ''high confidence'' ) (Table CCP6.2) ( [[#Gutt--2018|Gutt et al., 2018]] ; [[#Convey--2019|Convey and Peck, 2019]] ; [[#Bestley--2020|Bestley et al., 2020]] ). With projected sea ice retreat and associated change in prey distribution ( [[#Henley--2020|Henley et al., 2020]] ), foraging areas of sub-Antarctic sea birds and marine mammals will shift southwards, leading to elevated pressure on populations due to higher foraging costs during the breeding season ( ''medium confidence'' ) ( [[#Ropert-Coudert--2018|Ropert-Coudert et al., 2018]] ; [[#Bestley--2020|Bestley et al., 2020]] ; [[#Hindell--2020|Hindell et al., 2020]] ; [[#Hückstädt--2020|Hückstädt et al., 2020]] ; [[#Wege--2021|Wege et al., 2021]] ). These changes are particularly impacting emperor penguins ( ''Aptenodytes forsteri'' ) (Table CCP6.2), with the projected population declining close to extinction by 2100 under Business-As-Usual climate scenarios ( ''medium confidence'' ) ( [[#Jenouvrier--2020|Jenouvrier et al., 2020]] ; [[#Trathan--2020|Trathan et al., 2020]] ; [[#Jenouvrier--2021|Jenouvrier et al., 2021]] ), whereas population decline is halted by 2060 under the 1.5°C climate scenario ( ''low confidence'' ) ( [[#Jenouvrier--2020|Jenouvrier et al., 2020]] ).

'''Table CCP6.2 |''' Summary of observed impacts (and projected risks of climate change for polar marine, terrestrial and freshwater ecosystems identified in [[IPCC:Wg2:Chapter:Chapter-3#3.2.3|Section 3.2.3]] and Box 3.4 in [[IPCC:Wg2:Chapter:Chapter-3|Chapter 3]] of the IPCC SROCC ( [[#Meredith--2019|Meredith et al., 2019]] ).

{| class="wikitable"
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! '''Affected system'''

! '''Hazard'''

'''*Cascading effect'''

! '''Observed impacts, future risks and natural adaptations identified in SROCC (confidence level)'''

|-
| colspan="3"| ''Arctic marine ecosystems''

|-
| Primary producers (PP-1)

| Sea ice loss

\* Freshening

\* Stratification

| Impact: timing (earlier and later blooms), distribution and magnitude (&gt;30% increase in annual net primary production since 1998) ( ''high confidence'' )

|-
|
| Acidification

| Adaptation: phytoplankton may compensate for decrease in pH

|-
| Zooplankton

| \* PP-1

| Impact: changing production and community composition ( ''medium confidence'' )

|-
| Benthos

| \* PP-1

| Impact: changing production and biodiversity ( ''medium confidence'' )

|-
|
| Acidification

| Risk: effects on zooplankton and pteropods depends on climate scenario and species’ sensitivity/adaptive capacity

|-
| Fish

| Warming

\* Prey changes

| Impact: northward expanding ranges of sub-Arctic/boreal species (e.g., Atlantic cod) in Bering Sea (Detection— ''high confidence'' , Attribution— ''medium confidence'' ) negatively affecting Arctic polar cod ( ''medium confidence'' )

|-
|
| \* Prey declines

| Risk: decreasing production of walleye pollock, Pacific cod and arrowtooth flounder, due to declines in large copepods ( ''medium confidence'' )

|-
| Birds and marine mammals

| Sea ice loss

| Impact: phenological, behavioural, physiological and distributional changes; endemic marine mammals have little scope to move northwards in response to warming ( ''high confidence'' )

|-
| Polar bears

| Sea ice timing, distribution, thickness

| Impact: phenological shifts, and changes in distribution, denning, foraging behaviour and survival rates ( ''hi'' ''gh co'' ''nfidence'' )

|-
| colspan="3"| ''Antarctic marine ecosystems''

|-
| Primary productivity

| Sea ice loss

\* Freshening

\* Stratification

| Impact: little overall change in biomass at circumpolar scale from 1998 to 2006, but sub-regional differences ( ''medium confidence'' ); changes difficult to detect and attribute to climate change

|-
| Microbes

| Acidification

| Impact: detrimental effect on primary production and changes to the structure and function of microbial communities ( ''medium confidence'' )

|-
| Antarctic krill

| Warming

| Impact: declines in abundance in the South Atlantic sector ( ''medium confidence'' ); may not represent a long-term, climate-driven trend but a decline following a period of anomalous peak abundance ( ''low confidence'' )

|-
|
| Risk: southward range shift due to changes in the location of the optimum conditions for growth and recruitment, with decreases most apparent in the areas with the most rapid warming, such as the southwest Atlantic/Weddell Sea region ( ''medium confidence'' )

|-
| Zooplankton

| Acidification

| Risk: vulnerability of pteropods through effects on eggs ( ''medium confidence'' )

|-
| Benthos

| Sea ice loss

| Risk: increase of biomass on the Antarctic continental shelf as productivity from longer phytoplankton blooms outweighs ice-scour mortality ( ''low confidence'' )

|-
|
| Sea ice loss

| Risk: shallow-water communities may become dominated by macroalgae due to increases in the amount of light (possible loss of endemic species by 12% due to warming temperatures) ( ''low confidence'' )

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| Fish

| Warming

| Risk: icefish may be displaced from shallow regions around sub-Antarctic islands ( ''low confidence'' )

|-
| Birds and marine mammals

| Sea ice cover

| Impact: predictability of foraging grounds and sea ice cover associated with climate are main drivers of population changes: increases for gentoo penguins (decreases for Adélie, chinstrap, king and Emperor penguins) ( ''high confidence'' )

|-
| colspan="3"| ''Arctic terrestrial and freshwater ecosystems''

|-
| Vegetation

| Warming

| Impact: greening ( ''high confidence'' )

|-
|
| Risk: decrease in tundra areal extent &gt;50% by 2050; wood shrubs expected to increase ( ''medium confidence'' )

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| Vertebrates

| Warming

| Impact: expanding range into Arctic

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| Freshwater primary productivity

| \* Increased runoff

\* Increased permafrost thaw

| Impact: increased productivity in rivers, lakes and coastal areas

|-
|
| Risk: expected to mobilise stores of pollutants

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| Pathogens

| Warming

| Impact: expanding range into Arctic

|-
|
| Risk: mobilisation may increase in high latitudes, including anthrax from frozen carcasses possibly released from permafrost

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| Fish

| \* Freshwater winter habitat

\* Increased discharge

| Risk: disruption of the life history of Arctic freshwater fish

|-
|
| \* Warming freshwater

| Risk: may make some surface waters inhospitably warm for cold water fish species

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| Biodiversity

| Warming

| Impact: sub-Arctic biodiversity expanding into Arctic

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| Reindeer/caribou

| Climate factors

| Impact: reindeer/caribou declined overall without adaptation ( ''high confidence'' ), with climate affecting many aspects of their life history ( ''medium confidence'' )

|-
|
| Risk: domesticated reindeer/caribou can be affected by fire, which reduces pasture, as well as by increased ice-on-snow, which can cause starvation

|-
| colspan="3"| ''Antarctic terrestrial and freshwater ecosystems''

|-
| Terrestrial biota

| \* Increased coastal ice melt

| Impact: increasing coastal ice-free areas available for colonisation ( ''high confidence'' )

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| Alien species

| Warming

| Risk: barriers to alien species reduce, affecting terrestrial biodiversity ( ''medium confidence'' )

|}

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==== CCP6.2.1.2 Ocean warming and sea ice changes affect marine primary productivity ====

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In the central Arctic Ocean, primary productivity remains low ( ''medium confidence'' ), mostly due to persisting nutrient and light limitations ( [[#Randelhoff--2016|Randelhoff and Guthrie, 2016]] ; [[#Ardyna--2020|Ardyna and Arrigo, 2020]] ). In inflowing (Barents and Chukchi Sea) and interior shelf regions (Laptev, Kara, and Siberian Sea), changes in sea ice extent, thickness and seasonal timing have altered light and mixing regimes, causing increasing overall productivity in open-water and under-ice habitats, and in leads ( ''high confidence'' ) (Table CCP6.2) ( [[#Ardyna--2020|Ardyna and Arrigo, 2020]] ; [[#Lannuzel--2020|Lannuzel et al., 2020]] ). Productivity changes are associated with the earlier-onset phytoplankton spring blooms and the increasing occurrence of autumn blooms, particularly at lower latitudes of the Arctic ( ''high confidence'' ) (Table CCP6.2) ( [[#Tedesco--2019|Tedesco et al., 2019]] ; [[#Ardyna--2020|Ardyna et al., 2020]] ). Ice algal communities are expected to change in productivity and species composition in response to the transition from a predominantly multi-year to a seasonal sea ice pack ( ''high confidence'' ) ( [[#Meredith--2019|Meredith et al., 2019]] ; [[#Tedesco--2019|Tedesco et al., 2019]] ; [[#Lannuzel--2020|Lannuzel et al., 2020]] ). Thinner sea ice increases the likelihood of surface flooding, resulting in the occurrence of snow-infiltration algal communities, which have been described in the Atlantic sector of the Arctic Ocean ( [[#Fernández-Méndez--2018|Fernández-Méndez et al., 2018]] ) and observed by Indigenous Peoples off northern Greenland (Box CCP6.2). The observed transition from marine-terminating to land-terminating glaciers has a negative impact on coastal ecosystems in Greenland ( ''medium confidence'' ) ( [[#Meire--2017|Meire et al., 2017]] ; [[#Hopwood--2018|Hopwood et al., 2018]] ) and Svalbard ( [[#Halbach--2019|Halbach et al., 2019]] ), as land-terminating glacial meltwater input increases stratification, which hinders vertical mixing and lowers local productivity, whereas marine-terminating glaciers can trigger upwelling, which supplies nutrients and enables higher productivity in the summer ( [[#Hopwood--2020|Hopwood et al., 2020]] ). Macroalgae and seagrass are generally expanding in the Arctic ( ''medium confidence'' ), though there are negative trends in some regions, partly due to increased runoff and turbidity from melting glaciers ( [[#Hopwood--2020|Hopwood et al., 2020]] ; [[#Krause-Jensen--2020|Krause-Jensen et al., 2020]] ). In the future Arctic Ocean, higher light availability in response to further sea ice decline and reduced deep mixing is projected to generally increase primary productivity ( ''medium confidence'' ), leading to an increase in phytoplankton biomass from 2000 to 2100 by ~20% for SSP1-2.6 and ~30–40% for SSP5-8.5 (Chapter 3) ( [[#Kwiatkowski--2020|Kwiatkowski et al., 2020]] ). However, productivity may increase less than predicted and eventually even decrease once nutrient limitation outweighs the benefits of higher light availability ( ''low confidence'' ) ( [[#Randelhoff--2020|Randelhoff et al., 2020]] ; [[#Seifert--2020|Seifert et al., 2020]] ).

Despite large-scale environmental changes in the Southern Ocean, such as the deepening of the summer mixed layer ( ''medium confidence'' ) ( [[#Panassa--2018|Panassa et al., 2018]] ; [[#Sallée--2021|Sallée et al., 2021]] ), and the expected impacts via altered nutrient entrainment, light availability and grazer encounter rates (Chapter 3) ( [[#Behrenfeld--2014|Behrenfeld and Boss, 2014]] ; [[#Llort--2019|Llort et al., 2019]] ), assessments indicated no consistent changes in primary production at the circumpolar scale, as sectors and regions show different trends ( ''medium confidence'' ). Although a global assessment found no overall changes in circumpolar primary production from 1998 to 2015 (Table CCP6.2) ( [[#Gregg--2019|Gregg and Rousseaux, 2019]] ), another study showed an overall increase in phytoplankton biomass in the mixed layer over the period 1997–2019 ( [[#Pinkerton--2021|Pinkerton et al., 2021]] ). Primary productivity has increased in the Pacific sector and decreased in the Atlantic sector and the Ross Sea ( ''low confidence'' ) ( [[#Kahru--2017|Kahru et al., 2017]] ; [[#Henley--2020|Henley et al., 2020]] ; [[#Pinkerton--2021|Pinkerton et al., 2021]] ). Higher productivity has also been observed in regions where rapid environmental changes occurred, such as in the vicinity of retreating IS and declining sea ice cover off the Antarctic Peninsula ( ''medium confidence'' ) ( [[#Henley--2020|Henley et al., 2020]] ; [[#Rogers--2020|Rogers et al., 2020]] ), although diversity of phytoplankton may decrease with warming temperatures and less sea ice ( ''limited evidence'' ) ( [[#Lin--2021|Lin et al., 2021]] ). In the future Southern Ocean, stronger upwelling due to strengthened westerly winds is projected to increase primary productivity at the circumpolar scale in the Antarctic Zone and to the north of the sub-Antarctic Front, but not in the sub-Antarctic Zone ( ''low to medium confidence'' ) (Chapter 3) ( [[#Henley--2020|Henley et al., 2020]] ; [[#Kwiatkowski--2020|Kwiatkowski et al., 2020]] ; [[#Pinkerton--2021|Pinkerton et al., 2021]] ). The largest changes are projected to occur after 2100 at 2–6°C warming of the surface ocean ( [[#Moore--2018|Moore et al., 2018]] ). Such an increase in Southern Ocean productivity will lead to a decline in global ocean productivity ( ''medium confidence'' ), due to nutrient trapping ( [[#Moore--2018|Moore et al., 2018]] ) and altered ocean carbon uptake through ecosystem feedbacks ( [[#Hauck--2018|Hauck et al., 2018]] ).

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==== CCP6.2.1.3 Impacts of ocean acidification vary spatially and among biotas ====

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In Arctic seas, areas with acidification levels corrosive to organisms forming CaCO 3 shells or skeletons expanded between the 1990s and 2010 ( ''high confidence'' ), with instances of extreme aragonite under-saturation ( [[#Ding--2017|Ding et al., 2017]] ; [[#Zhang--2020|Zhang et al., 2020]] ). Key species of diatom and picoeukaryote phytoplankton species yet appear relatively resilient to decreasing pH levels over a range of temperature and light conditions ( ''medium confidence'' ) (Table CCP6.2) ( [[#Thoisen--2015|Thoisen et al., 2015]] ; [[#Wolf--2018|Wolf et al., 2018]] ; [[#White--2020|White et al., 2020]] ). In contrast, there is evidence for species- and stage-specific sensitivities of zooplankton, pteropods and fishes ( ''high confidence'' ) (Table CCP6.2) ( [[#Bailey--2016|Bailey et al., 2016]] ; [[#Dahlke--2018|Dahlke et al., 2018]] ; [[#Thor--2018|Thor et al., 2018]] ). Warming, rising river-sediment discharge and coastal erosion in Arctic shelf regions are expected to increase the input of labile, often permafrost-derived organic carbon, the remineralisation of which further increases acidification rates ( ''medium confidence'' ) ( [[#Semiletov--2016|Semiletov et al., 2016]] ; [[#AMAP--2018b|AMAP, 2018b]] ; [[#Bröder--2018|Bröder et al., 2018]] ). Interactions with other physical changes, such as warming or freshening, are expected to aggravate the impacts of ocean acidification (Chapter 3) ( [[#Falkenberg--2018|Falkenberg et al., 2018]] ).

In the Southern Ocean, calcifying organisms are also most vulnerable to ocean acidification ( ''high confidence'' ) (Table CCP6.2), as evidenced by rates of calcification declining by 3.9% between 1998 and 2014 ( [[#Freeman--2015|Freeman and Lovenduski, 2015]] ). Calcifying species with low-magnesium calcite or mechanisms to protect their skeletons are less vulnerable to the corrosive effects of acidification than those using aragonite or high-magnesium calcite ( ''high confidence'' ) ( [[#Figuerola--2021|Figuerola et al., 2021]] ). In diatom-dominated communities, silicification diminishes with reduced pH levels, albeit with rates differing among taxa ( ''low confidence'' ) ( [[#Petrou--2019|Petrou et al., 2019]] ). Species-specific responses exist regarding growth and primary production, which are further strongly modulated by iron and light availability ( ''high confidence'' ) ( [[#Hoppe--2013|Hoppe et al., 2013]] ; [[#Trimborn--2013|Trimborn et al., 2013]] ; [[#Hoppe--2015|Hoppe et al., 2015]] ; [[#Henley--2020|Henley et al., 2020]] ; [[#Seifert--2020|Seifert et al., 2020]] ). A meta-analysis yielded different CO 2 thresholds for Antarctic organismal groups; for example, negative impacts emerged at &gt;1000 μ atm CO 2 in phytoplankton and at &gt;1500 μ atm CO 2 in invertebrates, whereas bacterial abundance was positively affected by ocean acidification ( [[#Hancock--2020|Hancock et al., 2020]] ). Species sensitivity can also differ strongly between life-cycle stages (Chapter 3.3.2). For instance, eggs and embryos of Antarctic krill are negatively impacted at &gt;1250 μ atm CO 2 whereas adults can thrive even at 1000–2000 µatm CO 2 over one year ( [[#Kawaguchi--2013|Kawaguchi et al., 2013]] ; [[#Ericson--2018|Ericson et al., 2018]] ).

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==== CCP6.2.1.4 Climate change alters food web dynamics ====

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Climate change has transformed Arctic marine ecosystems from sea ice-associated to open-water production regimes, with profound impacts on trophic energy transfer efficiencies and pathways ( ''high confidence'' ) ( [[#Behrenfeld--2017|Behrenfeld et al., 2017]] ; [[#Meredith--2019|Meredith et al., 2019]] ; [[#Huntington--2020|Huntington et al., 2020]] ) as well as benthic–pelagic coupling ( ''medium confidence'' ) ( [[#Birchenough--2015|Birchenough et al., 2015]] ; [[#Degen--2016|Degen et al., 2016]] ; [[#Solan--2020|Solan et al., 2020]] ). Shifts in bloom phenology favour small phytoplankton and smaller zooplankton over large lipid-rich macro-zooplankton, leading to longer, less efficient food chains ( ''medium confidence'' ) ( [[#Aarflot--2018|Aarflot et al., 2018]] ; [[#Feng--2018|Feng et al., 2018]] ; [[#Kimmel--2018|Kimmel et al., 2018]] ; [[#Weydmann--2018|Weydmann et al., 2018]] ; [[#Møller--2020|Møller and Nielsen, 2020]] ). In the Beaufort Sea and Svalbard waters, earlier spring phytoplankton blooms have resulted in a mismatch in dynamics between microalgae and herbivorous copepods ( [[#Renaud--2018|Renaud et al., 2018]] ; [[#Dezutter--2019|Dezutter et al., 2019]] ). In the Bering Sea, zooplankton declines following the particularly pronounced sea ice retreats in 2017 and 2018 were associated with reduced forage fish production ( [[#Duffy-Anderson--2019|Duffy-Anderson et al., 2019]] ) as well as multi-trophic mortality of ctenophore, fish, bird and mammal species, coupled with severe emaciation, reproductive failure, disease and high mortality rates of sea bird predators ( [[IPCC:Wg2:Chapter:Chapter-14#14.4|Section 14.4.4.2]] ) ( [[#Jones--2019|Jones et al., 2019]] ; [[#Maekakuchi--2020|Maekakuchi et al., 2020]] ; [[#Piatt--2020|Piatt et al., 2020]] ; [[#Romano--2020|Romano et al., 2020]] ). Species range shifts have restructured higher trophic levels in Arctic food webs ( ''high confidence'' ) (Table CCP6.2; CCP6.2.3.3 Chapter 3) ( [[#Huntington--2020|Huntington et al., 2020]] ). In the northern Barents Sea, increased predation mortality for key species and incursions of boreal fish have induced entire ecosystem reorganisation ( [[#Degen--2016|Degen et al., 2016]] ; [[#Pecuchet--2020a|Pecuchet et al., 2020a]] ; [[#Pecuchet--2020b|Pecuchet et al., 2020b]] ). Regional taxonomic and functional diversity increased with immigration of boreal species, although the ongoing decline in Arctic species suggests high species turnover (Table CCP6.2) ( [[#Frainer--2017|Frainer et al., 2017]] ). Recent marine heatwaves induced rapid and profound food web changes unprecedented over the last four decades ( [[#Siddon--2020|Siddon et al., 2020]] ).

Climate impacts on Arctic marine food webs will be profound and intensify with GWL ( ''high confidence'' ), regardless of mitigation scenarios due to multi-decadal lags in sea ice extent and atmospheric carbon (WGI) ( [[#Jones--2020|Jones et al., 2020]] ). However, the exact nature of these impacts remains unclear due to attenuating and amplifying dynamics of both top-down and bottom-up processes in polar food webs and the management of fisheries ( ''high confidence'' ) (Chapter 3) ( [[#Cavicchioli--2019|Cavicchioli et al., 2019]] ; [[#Meredith--2019|Meredith et al., 2019]] ). Projected sea ice loss is associated with a &gt;50% decline in the density of large zooplankton species by 2100 (relative to early 21st century levels) in the southern Bering Sea and a net increase in large zooplankton in the Northern Bering Sea in scenarios without carbon mitigation (Representative Concentration Pathway (RCP) 8.5), whereas these declines are roughly half the magnitude under moderate mitigation scenarios (RCP4.5) ( [[#Hermann--2019|Hermann et al., 2019]] ; [[#Kearney--2020|Kearney et al., 2020]] ). Warming is expected to reduce the quantity and quality of lipid-rich copepod prey ( ''high confidence'' ) ( [[#Aarflot--2018|Aarflot et al., 2018]] ; [[#Kimmel--2018|Kimmel et al., 2018]] ; [[#Bouchard--2020|Bouchard and Fortier, 2020]] ; [[#Møller--2020|Møller and Nielsen, 2020]] ; [[#Mueter--2020|Mueter et al., 2020]] ), leading to declines in survival and growth of multiple upper-trophic level fish species; these impacts are amplified over time under low mitigation scenarios (RCP8.5) ( ''high confidence'' ) (CCP6.2.1.1) ( [[#Dahlke--2018|Dahlke et al., 2018]] ; [[#Holsman--2020|Holsman et al., 2020]] ; [[#Mueter--2020|Mueter et al., 2020]] ; [[#Oke--2020|Oke et al., 2020]] ; [[#Reum--2020|Reum et al., 2020]] ; [[#Thorson--2020|Thorson et al., 2020]] ; [[#Whitehouse--2021|Whitehouse et al., 2021]] ). Marine mammals and sea birds will continue to attenuate climate change impacts by shifting their diets and behaviour ( ''medium confidence'' ) (Table CCP6.2) ( [[#Hamilton--2017|Hamilton et al., 2017]] ; [[#Lowther--2017|Lowther et al., 2017]] ; [[#Lydersen--2017|Lydersen et al., 2017]] ; [[#Vihtakari--2018|Vihtakari et al., 2018]] ; [[#Boveng--2020|Boveng et al., 2020]] ). However, sea birds generally have low temperature-mediated plasticity of reproductive timing, making them vulnerable to mismatches with their prey and limiting long-term adaptation ( ''medium confidence'' ) ( [[#Keogan--2018|Keogan et al., 2018]] ; [[#Kharouba--2020|Kharouba and Wolkovich, 2020]] ; [[#Piatt--2020|Piatt et al., 2020]] ; [[#Samplonius--2021|Samplonius et al., 2021]] ).

Many factors have contributed to changes in Antarctic food webs, including historical exploitation of fish and marine mammals as well as changes driven by the ozone hole and climate factors ( [[#Meredith--2019|Meredith et al., 2019]] ; [[#Morley--2020|Morley et al., 2020]] ; [[#Grant--2021|Grant et al., 2021]] ). Most documented changes resulting from warming and sea ice losses relate to shifts in ranges and dynamics of species, with most impacts occurring around the Antarctic Peninsula (CCP6.2.1.1; Table CCP6.2).

The projected general rise in primary production in Antarctic seas by 2100 (CCP6.2.1.2) suggests a concomitant increase in the abundance of higher trophic species, but changes in the structure and function of food webs will vary ( [[#McCormack--2021|McCormack et al., 2021]] ; McCormack, accepted) depending on regional differences in changing drivers ( [[#Morley--2020|Morley et al., 2020]] ; [[#Cavanagh--2021|Cavanagh et al., 2021]] ; [[#Grant--2021|Grant et al., 2021]] ). Primary production in open water habitats is expected to be supported by smaller phytoplankton species in the future ( [[#Henley--2020|Henley et al., 2020]] ), which could increase the relative importance of the copepod-mesopelagic fish pathway (McCormack, accepted), because krill prefer larger diatoms as food ( [[#Siegel--2016|Siegel, 2016]] ). The optimum habitat for Antarctic krill is expected to decline with a shortening of suitable season for krill growth and reproduction, particularly in the northern Scotia and Bellingshausen Seas ( ''medium confidence'' ) ( [[#Veytia--2020|Veytia et al., 2020]] ), although changes may be difficult to distinguish from natural variability until later in the century ( [[#Sylvester--2021|Sylvester et al., 2021]] ). More subtle and unpredictable changes may occur in the structure and relative importance of energy pathways in the food webs ( [[#Trebilco--2020|Trebilco et al., 2020]] ). Small mesopelagic fish are increasingly recognised for their importance as mid-trophic level species in the Southern Ocean, particularly in the sub-Antarctic zone ( [[#Caccavo--2021|Caccavo et al., 2021]] ) and Central Indian Sector ( [[#Subramaniam--2020|Subramaniam et al., 2020]] ; [[#McCormack--2021|McCormack et al., 2021]] ). Although salps have long been considered to be competitors of Antarctic krill ( [[#Suprenand--2017|Suprenand and Ainsworth, 2017]] ; [[#Rogers--2020|Rogers et al., 2020]] ), they provide a third energy pathway in pelagic food webs and, given the changing ocean conditions and their preference for smaller phytoplankton, may increase in importance for copepods ( ''low confidence'' ) ( [[#Plum--2020|Plum et al., 2020]] ; [[#Trebilco--2020|Trebilco et al., 2020]] ; [[#McCormack--2021|McCormack et al., 2021]] ; [[#Pauli--2021|Pauli et al., 2021]] ; McCormack, accepted). Declining ice shelves, such as those off the Antarctic Peninsula, will open up new pelagic and benthic habitats (CCP6.2.1.1) with expected increases in productivity of benthic assemblages in the new areas ( [[#Barnes--2017|Barnes, 2017]] ; [[#Morley--2020|Morley et al., 2020]] ; [[#Brasier--2021|Brasier et al., 2021]] ; [[#Gutt--2021|Gutt et al., 2021]] ).

<div id="CCP6.2.2" class="h2-container"></div>

<span id="ccp6.2.2-terrestrial-and-freshwater-ecosystems"></span>
=== CCP6.2.2 Terrestrial and Freshwater Ecosystems ===

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Since the publication of AR5 ( [[#IPCC--2014|IPCC, 2014]] ) and SROCC ( [[#IPCC--2019|IPCC, 2019]] ) and their findings (Table CCP6.2), more studies confirm rapid changes in Arctic terrestrial and freshwater systems including increased permafrost thaw, changes to tundra hydrology and vegetation (overall greening of the tundra, regional browning of tundra and boreal forests), coastal and riverbank erosion ( ''high confidence'' ) ( [[#Canadell--2021|Canadell et al., 2021]] ; [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ), reduced duration of snow cover and river and lake ice, increased rain-on-snow events, and reduced land-ice extent and thickness ( [[#Bieniek--2018|Bieniek et al., 2018]] ; [[#Brown--2018|Brown et al., 2018]] ). Climate change continues to alter vegetation and attendant biodiversity, with divergent regional trends across the Arctic due to disparities in local conditions and changes in growing seasons ( [[#Zhu--2016|Zhu et al., 2016]] ; [[#Taylor--2020|Taylor et al., 2020]] ). Warming facilitates woody vegetation growth in northeastern Siberia, western Alaska, and northern Quebec ( [[#Song--2018|Song et al., 2018]] ; [[#García%20Criado--2020|García Criado et al., 2020]] ), as well as a northward expansion of shrub vegetation and sub-Arctic and boreal species ( [[#Davidson--2020|Davidson et al., 2020]] ).

Further evidence shows that warming and changes to the Arctic hydrologic cycle increase the risk of wildfire ( ''medium confidence'' ) ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ). Both the frequency of and the area burned by wildfires during recent years are unprecedented compared with the last 10,000 years ( ''high confidence'' ) ( [[#Meredith--2019|Meredith et al., 2019]] ; [[#Irannezhad--2020|Irannezhad et al., 2020]] ). Fire risk levels are projected to increase across most tundra and boreal regions, and interactions between climate and shifting vegetation ( [[#Song--2018|Song et al., 2018]] ) will influence future fire intensity and frequency ( ''medium confidence'' ) ( [[#Curtis--2018|Curtis et al., 2018]] ).

For all warming scenarios, declines in snow cover in the Arctic by 2050 (Table CCP6.1) may accelerate vascular plant, moss and lichen extinction rates (32% for Arctic–alpine and 12% for boreal species), especially after the tipping point of 20–30% decrease in snow cover duration is passed ( [[#Niittynen--2018|Niittynen et al., 2018]] ). Even though the overall regional water cycle will intensify, including increased precipitation, evapotranspiration and river discharge to the Arctic Ocean (Table CCP6.1), snow and permafrost decline may lead to further soil drying ( ''medium confidence'' ) ( [[#Meredith--2019|Meredith et al., 2019]] ). Glacial ice melt poses a risk to ecosystems and people through remobilisation of sequestered hazardous waste and transported pollutants (Table CCP6.3) ( [[#Wang--2019|Wang et al., 2019]] ).

In the Antarctic, there is further ''high agreement'' since the publication of SROCC that melt and ice-free areas are causing increases in the rates of colonisation and utilisation of coastal environments by terrestrial biota and land-based colonies of seals and birds ( [[#Gutt--2021|Gutt et al., 2021]] ), although colonisation rates remain variable ( [[#Ruiz-Fernandez--2017|Ruiz-Fernandez et al., 2017]] ; [[#Bokhorst--2021|Bokhorst et al., 2021]] ). Soil temperatures along the Antarctic Peninsula are now sufficient for germination of non-native plants; invasions by non-endemic species are expected to increase with rising temperatures ( ''high confidence'' ) ( [[#Bokhorst--2021|Bokhorst et al., 2021]] ), posing a risk to endemic polar species ( ''medium confidence'' ) ( [[#Chown--2019|Chown and Brooks, 2019]] ; [[#Gutt--2021|Gutt et al., 2021]] ).

Vegetation responses to warming are contingent on water availability and local temperature ( ''medium confidence'' ) ( [[#Guglielmin--2014|Guglielmin et al., 2014]] ; [[#Royles--2015|Royles and Griffiths, 2015]] ; [[#Amesbury--2017|Amesbury et al., 2017]] ; [[#Cannone--2017|Cannone et al., 2017]] ; [[#Charman--2018|Charman et al., 2018]] ; [[#Robinson--2018|Robinson et al., 2018]] ; [[#Stelling--2018|Stelling et al., 2018]] ), which vary greatly around Antarctica (Figure CCP6.1) ( [[#Turner--2020a|Turner et al., 2020a]] ). Antarctic terrestrial ecosystem responses to changes in water availability are not homogeneous ( [[#Ball--2015|Ball and Levy, 2015]] ; [[#Sadowsky--2016|Sadowsky et al., 2016]] ; [[#Fuentes-Lillo--2017|Fuentes-Lillo et al., 2017]] ; [[#Gooseff--2017|Gooseff et al., 2017]] ; [[#Schroeter--2017|Schroeter et al., 2017]] ; [[#Lee--2018|Lee et al., 2018]] ). West Antarctica is showing evidence of greening in the dominant cryptogrammic vegetation, with greater growth in mosses ( ''high confidence'' ) ( [[#Casanova-Katny--2016|Casanova-Katny et al., 2016]] ; [[#Amesbury--2017|Amesbury et al., 2017]] ; [[#Shortlidge--2017|Shortlidge et al., 2017]] ; [[#Charman--2018|Charman et al., 2018]] ; [[#Prather--2019|Prather et al., 2019]] ). Peatland ecosystems may increase on the west Antarctic Peninsula with future warming ( ''low confidence'' ) ( [[#Yu--2016|Yu et al., 2016]] ; [[#Loisel--2017|Loisel et al., 2017]] ). In contrast, some parts of East Antarctica and the subantarctic islands to the north have been experiencing a drying climate, with declining health of mosses and other vegetation ( ''high confidence'' ) ( [[#Bergstrom--2015|Bergstrom et al., 2015]] ; [[#Bramley-Alves--2015|Bramley-Alves et al., 2015]] ; [[#Robinson--2018|Robinson et al., 2018]] ; [[#Bergstrom--2021|Bergstrom et al., 2021]] ).

Antarctica encountered its first reported heatwave in 2020 (Table CCP6.1). Such abrupt heating can cause wide-ranging effects on biota, from flash-flooding damage and dislodgement of plants to excess melt waters supplying moisture to arid Antarctic ecosystems. This suggests that increased melt may reverse the drying trend if plant communities remain connected to melt streams and there is sufficient precipitation ( ''high agreement, limited evidence'' ) ( [[#Bergstrom--2021|Bergstrom et al., 2021]] ).

Warming of the Antarctic Peninsula has resulted in increased soil microbial abundance and biomass. However, this trend is not as great in southern colder locations ( ''medium confidence'' ) (e.g., [[#Kim--2018|Kim et al., 2018]] ; [[#Newsham--2019|Newsham et al., 2019]] ), as the microbial community structure is affected by vegetation cover and water availability ( ''high confidence'' ) ( [[#Dennis--2019|Dennis et al., 2019]] ; [[#Newsham--2019|Newsham et al., 2019]] ).

Antarctic terrestrial invertebrate communities on the West Antarctic Peninsula may be controlled more by vegetation and water availability than by air temperature ( ''medium confidence'' ) ( [[#Bokhorst--2016|Bokhorst and Convey, 2016]] ; [[#Knox--2016|Knox et al., 2016]] ; [[#Andriuzzi--2018|Andriuzzi et al., 2018]] ; [[#Prather--2019|Prather et al., 2019]] ; [[#Newsham--2020|Newsham et al., 2020]] ). Evidence from laboratory studies, field programmes and sedimentary records indicate that Antarctic freshwater ecosystems may become more productive under climate warming scenarios ( ''medium confidence'' ) (e.g., [[#Schiaffino--2011|Schiaffino et al., 2011]] ; [[#Borghini--2016|Borghini et al., 2016]] ; [[#Píšková--2019|Píšková et al., 2019]] ; [[#Čejka--2020|Čejka et al., 2020]] ).

<div id="CCP6.2.3" class="h2-container"></div>

<span id="ccp6.2.3-food-fibre-and-other-ecosystem-products"></span>
=== CCP6.2.3 Food, Fibre and Other Ecosystem Products ===

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Food and fibre production underpins regional identities, cultures and communities of practice and place in polar regions, are vital to local and distant economies (Table CCP6.4) and represent for fisheries a critical source of global nutrition and food security ( [[#Hicks--2019|Hicks et al., 2019]] ). Since SROCC, there is further evidence that climate change alterations of polar ecosystems increasingly challenge production of, and access to, sufficient, healthy and nutritious food, posing risks to future food and nutritional security within and beyond polar regions ( ''high confidence'' ).

'''Table CCP6.4 |''' Climate change impacts on Arctic and Antarctic fisheries and fishing communities. Additional detail in Table SMCCP6.3.

{| class="wikitable"
|-
! '''Driver'''

! '''Observed impacts and projected risks'''

! '''References'''

|-
| colspan="2"| ''Current and past climate change impacts''

|
|-
| Warming

| Fisheries productivity declined in multiple stocks across the Arctic including the Eastern Bering Sea (EBS), while Atlantic cod and other fisheries have increased.

| ( [[#Free--2019|Free et al., 2019]] ; [[#Cheung--2020|Cheung and Frölicher, 2020]] )

|-
| Extreme heat

| Commercially important fish species declined rapidly during recent MHWs (2016–2019), in the EBS due to reduced recruitment, increased metabolic demand and increased predation mortality, and it is probable that climate impacts have contributed to the closure of Pribilof islands blue king crab ( ''Paralithodes platypus'' ) fisheries.

| ( [[#Zheng--2018|Zheng and Ianelli, 2018]] ; [[#Duffy-Anderson--2019|Duffy-Anderson et al., 2019]] ; [[#Stabeno--2019|Stabeno et al., 2019]] ; [[#Basyuk--2020|Basyuk and Zuenko, 2020]] ; [[#Reum--2020|Reum et al., 2020]] ; [[#Thorson--2020|Thorson et al., 2020]] )

|-
| Temperature; shifting species distributions

| In the Barents Sea, northward redistribution of stocks led fisheries into previously unfished habitats, exposing benthic ecosystems to novel trawling impacts. Large-scale redistributions of Pacific cod (&gt;1000 km per decade) and other groundfish species have challenged fisheries management in the EBS; ~50% of the biomass is now located in the Northern Bering Sea (NBS), outside of historical survey areas and in a region where bottom trawling is prohibited (although pelagic gear is permitted).

| ( [[#Christiansen--2014|Christiansen et al., 2014]] ; [[#Jørgensen--2019|Jørgensen et al., 2019]] ; [[#Spies--2019|Spies et al., 2019]] ; [[#Stevenson--2019|Stevenson and Lauth, 2019]] )

|-
| OA, warming, winds

| Shellfish species such as snow crab are undergoing range contractions poleward in the Barents Sea and NBS, with increased catches in the north and declines in the south.

| ( [[#Jørgensen--2019|Jørgensen et al., 2019]] ; [[#Fedewa--2020|Fedewa et al., 2020]] ) (Cross-Chapter Box MOVING PLATE in Chapter 5)

|-
| Warming; poleward expansion

| Poleward expansion of Pacific salmon into Arctic watersheds and Greenland fjords presents both new opportunities and novel threats to key subsistence and commercial species such as Arctic char and Atlantic salmon.

| ( [[#Bilous--2020|Bilous and Dunmall, 2020]] ; [[#Nielsen--2020|Nielsen et al., 2020]] )

|-
| Warming; harmful algal blooms (HABs)

| Altered seasonal freshwater habitats are impacting salmon productivity and phenology of important salmon resources in Alaska and in the Fennoscandian North, with subsequent community-specific impacts on commercial and subsistence resources.

| ( [[#Brattland--2018|Brattland and Mustonen, 2018]] ; [[#Cline--2019|Cline et al., 2019]] ; [[#Mustonen--2020|Mustonen and Feodoroff, 2020]] ; [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] )

|-
| Multiple; sea ice

| Losses of winter sea ice to the north and west of the Antarctic Peninsula have enabled krill fishing vessels to fish all year round in that area.

| ( [[#Meredith--2019|Meredith et al., 2019]] )

|-
| colspan="2"| ''Future climate change impacts and risks''

|
|-
| Multiple

| Climate change impacts on the ecology and physiology of polar cod species contribute to expected increases in biomass and catch potential under high to moderate mitigation (RCP2.6 and RCP4.5) and reductions in groundfish recruitment and yield under low mitigation (RCP8.5) scenarios (CCP6.2.2) across a range of multispecies models.

| ( [[#Laurel--2016|Laurel et al., 2016]] ; [[#Spencer--2016|Spencer et al., 2016]] ; [[#Lotze--2018|Lotze et al., 2018]] ; [[#Spencer--2019|Spencer et al., 2019]] ; [[#Dahlke--2020|Dahlke et al., 2020]] ; [[#Grüss--2020|Grüss et al., 2020]] ; [[#Hollowed--2020|Hollowed et al., 2020]] ; [[#Reum--2020|Reum et al., 2020]] ; [[#Thorson--2020|Thorson et al., 2020]] )

|-
| Climate × management interaction

| Assuming no climate adaptation in current EBM, 50% declines (relative to projections under persistent current climate conditions) in EBS pollock and cod yield is ''likely'' under moderate carbon mitigation scenarios (RCP4.5), and ''very likely'' under low mitigation scenarios (RCP8.5).

| ( [[#Holsman--2020|Holsman et al., 2020]] ; [[#Reum--2020|Reum et al., 2020]] ; [[#Whitehouse--2021|Whitehouse et al., 2021]] )

|-
| Warming; ocean acidification (OA)

| Warming, OA, fish predators and thermal tolerance differentiate impacts across crab species in the Arctic; increased productivity and redistribution offshore is expected for tanner crab; red king crab and snow crab are projected to continue to shift north and decrease in productivity. OA is expected to impact demographics, altering harvest recommendations and biological reference points for some species of some shellfish and flatfish (e.g., red king crab, Northern rock sole) in projection simulations.

| ( [[#Punt--2014|Punt et al., 2014]] ; [[#Sawatzky--2020|Sawatzky et al., 2020]] ; [[#Punt--2021|Punt et al., 2021]] )

|-
| Climate × management interaction

| Multiple rights-based fisheries operate in the Arctic, increasing investment in long-term sustainability but reducing harvest portfolio diversity and increasing vulnerability to climate shocks.

| ( [[#Kasperski--2013|Kasperski and Holland, 2013]] ; [[#Ojea--2017|Ojea et al., 2017]] )

|-
| Multiple; sea ice

| Physical and biological changes in Antarctic waters are expected to result in net declines in krill habitat and growth potential, although one study indicates a potential increase. Reduction in the Antarctic ice pack is as ''likely as not'' to increase total season length in areas near to land-based predators.

| ( [[#Melbourne-Thomas--2016|Melbourne-Thomas et al., 2016]] ; [[#Piñones--2016|Piñones and Fedorov, 2016]] ; [[#Klein--2018|Klein et al., 2018]] ; [[#Rogers--2020|Rogers et al., 2020]] ; [[#Veytia--2020|Veytia et al., 2020]] )

|-
| Phytoplankton and temperature

| Projected changes in primary production and temperature are expected to cause declines in krill growth and availability to predators; impacts may be countered by reducing fisheries, signifying a potential conflict between fisheries and top predators.

| ( [[#Piñones--2016|Piñones and Fedorov, 2016]] ; [[#Klein--2018|Klein et al., 2018]] )

|}

<div id="CCP6.2.3.1" class="h3-container"></div>

<span id="ccp6.2.3.1-arctic-subsistence-resources"></span>
==== CCP6.2.3.1 Arctic subsistence resources ====

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Subsistence harvest of fish, sea birds and marine mammals is the basis for economic, cultural and spiritual connections with Arctic marine systems (Box CCP6.2)( [[#Fall--2013|Fall et al., 2013]] ; [[#Haynie--2016|Haynie and Huntington, 2016]] ; [[#Raymond-Yakoubian--2017|Raymond-Yakoubian et al., 2017]] ; [[#Slats--2019|Slats et al., 2019]] ), and nature-based livelihoods (e.g., caribou and reindeer ( ''Rangifer tarandus'' ) herding, fishing, hunting, trapping, small-scale forestry) are fundamental to Indigenous Peoples across the Arctic as they have been for millennia ( [[#Koivurova--2015|Koivurova et al., 2015]] ; [[#Betts--2016|Betts, 2016]] ; [[#Gavin--2018|Gavin et al., 2018]] ; [[#Raheem--2018|Raheem, 2018]] ; [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ). Climate change has impacted Indigenous subsistence resources across the Arctic ( ''very high confidence'' ) (SMCCP6.2), and future food systems and ecological connections are at risk from future climate change hazards interacting with non-climate pressures, some of which are mediated or amplified by novel conditions and opportunities in Arctic regions ( ''high confidence'' ) ( [[#Moerlein--2012|Moerlein and Carothers, 2012]] ; [[#Fall--2013|Fall et al., 2013]] ; [[#Raymond-Yakoubian--2017|Raymond-Yakoubian et al., 2017]] ; [[#Meredith--2019|Meredith et al., 2019]] ; [[#Slats--2019|Slats et al., 2019]] ; [[#Huntington--2020|Huntington et al., 2020]] ; [[#Huntington--2021|Huntington et al., 2021]] ). Increasing heatwaves, wildfires, extreme precipitation, permafrost loss and rapid seasonal snow and ice thaw events will further threaten terrestrial subsistence food resources across the Arctic ( ''high confidence'' ) (Table CCP6.3). Although climate impacts and non-climate factors systematically undermine access to and productivity of subsistence resources, resilience is inherently high for Indigenous Peoples, illustrating critical elements underpinning successful adaptation to climate change (Box CCP6.2) ( [[#Huntington--2021|Huntington et al., 2021]] ).

'''Table CCP6.3 |''' Illustrative examples of climate change impacts on subsistence resources in the Arctic.

{| class="wikitable"
|-
! '''Changing'''

'''drivers'''

! '''Observed impacts and projected risks'''

! '''References'''

|-
| Snow, ice, river environments

| Climate change is disrupting subsistence harvests for Indigenous Peoples in Arctic communities that depend on snow, ice and river environments for travel and access to subsistence resources.

| ( [[#Wildcat--2013|Wildcat, 2013]] ; [[#Meredith--2019|Meredith et al., 2019]] ; [[#Slats--2019|Slats et al., 2019]] )

|-
| Multiple

| Across the Canadian Arctic, multiple populations of reindeer and caribou are in decline, with 95% of assessed herds listed as rare, decreasing or ‘threatened’; reindeer and caribou abundances in the Alaska–Canada region have declined 56% over the past 20 years.

| ( [[#Russell--2018|Russell et al., 2018]] )

|-
| Multiple

| Reindeer herding is an important economic and Indigenous cultural activity in the Eurasian Arctic and is being affected by non-climate and climate events, including changes to thaw cycles, drought and unpredictable summer weather, which threaten pasture areas in Siberia. Although changes in vegetation and the freeze–thaw cycle are impacting Sami reindeer herding, adaptive measures by herders have been effective at offsetting multiple climate and non-climate impacts.

| ( [[#Furberg--2011|Furberg et al., 2011]] ; [[#Uboni--2020|Uboni et al., 2020]] ; [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] )

|-
| Sea ice; winds; visibility

| Loss of multi-year ‘mother ice’, declines in seasonal sea ice thickness and stability, and changes in winds and visibility have impacted the availability of, and access to, subsistence resources ( ''high confidence'' ) and have increased interactions between coastal communities and shipping, tourism and commercial fisheries, which directly impact human safety and well-being in Arctic communities ( ''high confidence'' ).

| ( [[#Stephenson--2015|Stephenson and Smith, 2015]] ; [[#Brinkman--2016|Brinkman et al., 2016]] ; [[#Melia--2016|Melia et al., 2016]] ; [[#Raymond-Yakoubian--2017|Raymond-Yakoubian et al., 2017]] ; [[#Ford--2019|Ford et al., 2019]] ; [[#Slats--2019|Slats et al., 2019]] ; [[#Huntington--2020|Huntington et al., 2020]] ; [[#Huntington--2021|Huntington et al., 2021]] )

|-
| Multiple

| Marine heatwave (MHW)-induced ecosystem changes contributed to widespread mortality events and declines in Northern Bering Sea sea birds and disrupted subsistence harvests in western Alaska.

| ( [[#Jones--2019|Jones et al., 2019]] ; [[#Piatt--2020|Piatt et al., 2020]] ; [[#Siddon--2020|Siddon et al., 2020]] )

|-
| Storminess; sea ice; whale migration timing; shipping

| Although some communities have seen reduced whale harvests due to climate impacts on survival and productivity, changes in storminess and whale migration timing have lengthened the July harvest season for Inuvialuit from Inuvik, Aklavik and Tuktoyaktuk. Changes in Beluga migration routes have increased accessibility to communities of Ulukhaktok and Paulatuk. In Western Greenland, loss of sea ice has both reduced access to sealing and increased subsistence and commercial harvest of Atlantic cod, halibut and other fish species. Increased impacts of noise and ship strikes associated with shipping are expected to impact subsistence species, especially seals and whales in Lancaster sound as well as the Pacific Arctic.

| ( [[#George--2017|George et al., 2017]] ; [[#Hauser--2018|Hauser et al., 2018]] ; [[#Loseto--2018|Loseto et al., 2018]] ; [[#Mustonen--2018a|Mustonen et al., 2018a]] )

|-
| Sea ice

| Changes in sea ice will continue to undermine subsistence resources and disrupt access by smaller scale commercial and subsistence-based ice-edge fishing.

| ( [[#Jacobsen--2018|Jacobsen et al., 2018]] ; [[#Ford--2019|Ford et al., 2019]] )

|-
| Shifting distributions; food web changes

| Shifting species distributions and climate change mediated food web reorganisation pose a risk to near-shore subsistence harvests that are essential to sustaining Indigenous Peoples in Western Greenland and the Northern Bering, Beaufort and Chukchi Seas; for example, cod biomass in the Inuvialuit region is projected to decrease 17% by 2100 (RCP8.5). Climate-related declines in harvester access drive projected declines in subsistence availability in Alaska.

| ( [[#Moerlein--2012|Moerlein and Carothers, 2012]] ; [[#Fall--2013|Fall et al., 2013]] ; [[#Brinkman--2016|Brinkman et al., 2016]] ; [[#Loseto--2018|Loseto et al., 2018]] ; [[#Steiner--2019|Steiner et al., 2019]] ; [[#Marsh--2020|Marsh and Mueter, 2020]] ; [[#Ribeiro--2021|Ribeiro et al., 2021]] )

|}

<div id="CCP6.2.3.2" class="h3-container"></div>

<span id="ccp6.2.3.2-agriculture-forestry-livestock-and-aquaculture"></span>
==== CCP6.2.3.2 Agriculture, forestry, livestock and aquaculture ====

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In addition to reindeer herding, Arctic agriculture primarily consists of local production of cool season crops, forage, small grains and livestock (sheep and goats) ( [[#Westergaard-Nielsen--2015|Westergaard-Nielsen et al., 2015]] ; [[#Natcher--2019|Natcher et al., 2019]] ). Short growing seasons, cold conditions, permafrost and moisture stress, especially along coasts, have historically limited production, but agriculture is generally increasing across the region ( [[#Westergaard-Nielsen--2015|Westergaard-Nielsen et al., 2015]] ). Although only ~0.2% of Alaska is farmland, area farmed and income from agriculture have increased 2% and 80%, respectively, since 2012 ( [[#United%20States%20Department%20of%20Agriculture--2017|United States Department of Agriculture, 2017]] ). It is ''likely'' that growing seasons have extended by 1–3 days per decade in interior Alaska, although some coastal areas exhibit declines in growing season ( [[#Lader--2018|Lader et al., 2018]] ).

Arctic temperatures rarely exceed thermal tolerances for crops (e.g., 35–38°C across corn, rice and grain), and warming will provide new opportunities for food and forage production in areas such as southwest Greenland and interior Alaska ( [[#Westergaard-Nielsen--2015|Westergaard-Nielsen et al., 2015]] ; [[#Tripathi--2016|Tripathi et al., 2016]] ; [[#Lader--2018|Lader et al., 2018]] ). Higher atmospheric CO 2 favours plant growth if soil quality and condition are sufficient, but benefits can be offset by increased heat and water stress associated with climate change ( [[#Tripathi--2016|Tripathi et al., 2016]] ; [[#Unc--2021|Unc et al., 2021]] ). Growing seasons in Alaska will lengthen by 48–87 d yr -1 relative to historical growing season length (1981–2010), and the start of growing season is expected to shift 1–4 weeks earlier ( [[#Lader--2018|Lader et al., 2018]] ). Feasible growing areas across the Arctic are expected to shift northward and increase within the 55°–69°N region ( [[#King--2018|King et al., 2018]] ). Permafrost thaw (Table CCP6.1) increases drainage, which is a potential benefit, but can also increase erosion, subsidence and irregular surfaces, inhibiting agriculture ( [[#Lader--2018|Lader et al., 2018]] ). Conversion of Arctic soils to croplands may also release carbon stored in vegetation and soils ( [[#Unc--2021|Unc et al., 2021]] ).

Arctic aquaculture contributes approximately 2% to global farm production (primarily Norwegian salmon ( ''Salmo salar'' ) as well as finfish in Iceland and Sweden and shellfish in Alaska), and will face increasing challenges from climate change ( [[#Troell--2017|Troell et al., 2017]] ) including increased frequency of storms (impacting sea farms), extreme temperatures and warmer conditions that favour pathogens, parasites and harmful algal blooms. Aquaculture feeds often depend on small pelagic fish or krill and supply may be affected by climate impacts on fisheries (Table CCP6.6) ( [[#Troell--2017|Troell et al., 2017]] ; [[#Chen--2018|Chen and Tung, 2018]] ; [[#Mørkøre--2020|Mørkøre et al., 2020]] ). Integrated policies and coordination across multiple food production sectors in Arctic regions are needed to address climate opportunities and challenges ( [[#Altdorff--2021|Altdorff et al., 2021]] ; [[#Unc--2021|Unc et al., 2021]] ).

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<span id="ccp6.2.3.3-commonalities-in-impacts-and-risks-across-polar-fisheries"></span>
==== CCP6.2.3.3 Commonalities in impacts and risks across polar fisheries ====

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Fisheries play an increasingly important role in addressing global food and nutritional deficits ( [[IPCC:Wg2:Chapter:Chapter-3#3.6.3|Section 3.6.3]] )( [[#Béné--2016|Béné et al., 2016]] ; [[#Ding--2017|Ding et al., 2017]] ; [[#Hicks--2019|Hicks et al., 2019]] ; [[#Costello--2020|Costello et al., 2020]] ), especially as climate change has already reduced global yields from key crops ( [[#Myers--2017|Myers et al., 2017]] ; [[#Ray--2019|Ray et al., 2019]] ; [[#Thiault--2019|Thiault et al., 2019]] ). Antarctic and Arctic systems support some of the world’s largest fisheries, including those for Antarctic krill and Arctic walleye pollock ( ''Gadus chalcogrammus'' ), which constitute a critical source of protein and macronutrients to a growing population of seafood consumers, as well as various aquaculture and livestock feeds (Cross-Chapter Box MOVING PLATE in Chapter 5) (Table CCP6.4) ( [[#Huntington--2013|Huntington et al., 2013]] ; [[#Raheem--2018|Raheem, 2018]] ; [[#Hicks--2019|Hicks et al., 2019]] ; [[#Steiner--2019|Steiner et al., 2019]] ; [[#FAO--2020|FAO, 2020]] ; [[#Cavanagh--2021|Cavanagh et al., 2021]] ; [[#Grant--2021|Grant et al., 2021]] ; [[#Murphy--2021|Murphy et al., 2021]] ). Marine sources of protein and nutrition are important in transformational future scenarios where dietary shifts and provisioning policies provide multiple co-benefits to equity, food security and carbon mitigation ( [[#Springmann--2016|Springmann et al., 2016]] ; [[#Poore--2018|Poore and Nemecek, 2018]] ; [[#Thiault--2019|Thiault et al., 2019]] ; [[#Kim--2020|Kim et al., 2020]] ). Shifting spatial distributions of fish stocks have led to transboundary management challenges in the Atlantic, Bering Sea and Arctic areas previously inaccessible due to sea ice (Table CCP6.6) ( [[#Gullestad--2020|Gullestad et al., 2020]] ).

Cascading and interacting effects of climate change impacts in polar regions (Table CCP6.1) will reduce access to, and productivity of, future fisheries, and pose significant risks to regional and global food and nutritional security that increase with atmospheric carbon levels and declines in sea ice ( ''high confidence'' ) (Table CCP6.6). Although it is expected that fisheries will continue to contract poleward under future warming (Cross-Chapter Box MOVING PLATE in Chapter 5) (Table CCP6.4) ( [[#Alabia--2018|Alabia et al., 2018]] ; [[#Morley--2018|Morley et al., 2018]] ; [[#Stevenson--2019|Stevenson and Lauth, 2019]] ; [[#Caccavo--2021|Caccavo et al., 2021]] ; [[#Grant--2021|Grant et al., 2021]] ), global and regional models differ in their projections of fisheries catch potential for the polar regions under climate change. For example, some global-scale models project increases in potential fishery yields in Arctic Canada ( [[#Cheung--2018|Cheung, 2018]] ; [[#Bindoff--2019|Bindoff et al., 2019]] ; [[#Tai--2019|Tai et al., 2019]] ), whereas many observational studies and high-resolution regional projections suggest overall declines in biomass, productivity and yield associated with warming and loss of sea ice in multiple regions such as the Bering Sea ( ''medium confidence'' ) ( [[#Free--2019|Free et al., 2019]] ; [[#Hollowed--2020|Hollowed et al., 2020]] ; [[#Holsman--2020|Holsman et al., 2020]] ; [[#Mueter--2020|Mueter et al., 2020]] ; [[#Reum--2020|Reum et al., 2020]] ). Reduced production of macronutrients and protein by polar marine sources will disproportionately impact people already experiencing food and nutritional scarcity ( [[#Myers--2017|Myers et al., 2017]] ), marine-dependent communities within and beyond polar regions, and women and children who require higher quantities of macronutrients ( ''high confidence'' ).

Large-scale commercial fisheries are expected to continue to operate in polar regions ( ''high confidence'' ) ( [[#Barange--2018|Barange et al., 2018]] ; [[#Cavanagh--2021|Cavanagh et al., 2021]] ; [[#Grant--2021|Grant et al., 2021]] ), and will shift poleward ( ''high confidence'' ) toward geopolitical and management boundaries ( ''high confidence'' ) (CCP6.3.2.3; Table CCP6.6). Warming and climate impacts will continue to impact transboundary stocks and increase the potential for conflict in fisheries management ( [[#Pinsky--2018|Pinsky et al., 2018]] ; [[#Mendenhall--2020|Mendenhall et al., 2020]] ; [[#Palacios-Abrantes--2020|Palacios-Abrantes et al., 2020]] ; [[#Sumaila--2020|Sumaila et al., 2020]] ). Increased distances from ports to redistributed fishing grounds as well as increased frequency of storms and other extreme events are expected to increase risks and costs for fishery operations ( ''medium confidence'' ) and impact shore-based infrastructure and emergency response services (CCP6.2.4). Observed and expected increases in mobile ice combined with abrupt wind can create major hazards for fish operators in Antarctica and the Arctic, with consequences to human safety and total revenue (Dawson and et al., 2017; [[#Barber--2018|Barber et al., 2018]] ; [[#Grant--2021|Grant et al., 2021]] ). There will be increased demand for new port infrastructure across the Arctic ( ''high confidence'' ); new ports have already been proposed for the Northern Bering Sea, and small craft harbour investments are being considered across Arctic Canada and Greenland. Ecosystem-based management (EBM), increasing diversity and flexibility in harvest portfolios as well as access to high-resolution ecological forecasts and projections, and climate-informed advice will promote adaptation and climate resilience in fisheries (Dawson and et al., 2017; [[#Brooks--2018|Brooks et al., 2018]] ; [[#Karp--2019|Karp et al., 2019]] ; [[#Hollowed--2020|Hollowed et al., 2020]] ). Coupling adaptation measures with global carbon mitigation strategies substantially decreases climate change risks to polar fisheries ( ''very high confidence'' ) (CCP6.3).

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<span id="faq-ccp6.1-how-do-changes-in-ecosystems-and-human-systems-in-the-polar-regions-impact-everyone-around-the-globe-how-will-changes-in-polar-fisheries-impact-food-security-and-nutrition-around-the-world"></span>
=== FAQ CCP6.1 | How do changes in ecosystems and human systems in the polar regions impact everyone around the globe? How will changes in polar fisheries impact food security and nutrition around the world? ===

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''Polar regions are commonly known to be experiencing particularly fast and profound climate change, which strongly affects areas and people all around the world in several ways. Physical processes taking place in these regions are critically important for the global climate and sea level. Less known is that regional climate-driven changes of ecosystems and human communities will also have far-reaching impacts on a number of sectors of human societies at lower latitudes.''

Climate change has triggered rapid, unprecedented and cascading changes in polar regions that have profound implications for ecosystems and people globally. Although physically remote from the largest population centres, polar systems are inextricably linked to the rest of the world through interconnected ocean currents, atmospheric interactions and weather, ecological and social systems, commerce and trade. The nutrient-rich waters of the polar regions fuel some of the most productive marine ecosystems on earth, which in turn support fisheries for species packed with vital macronutrients that are essential for human health and well-being. The largest most sustainable fisheries in the world are located in polar waters, where a mix of ice, seasonal light and cold nutrient-rich waters fuel schools of millions of fish that swell and retract in numbers across the years, reflecting interlaced cycles of icy cold waters, lipid-rich prey and abundant predators. Polar systems thus exist in a productive balance that has supported vibrant ecocultural connections between Indigenous Peoples and the Arctic for millennia and has supported global food production and trade for centuries. Climate change increasingly destabilises this balance with uncertain outcomes for Indigenous Peoples and local residents in the Arctic as well as for the rest of the world. Triggered by warming oceans and air temperatures, accelerated melting of sea ice, glaciers and IS in polar regions in turn impacts ocean salinity, sea levels and circulation throughout the global ocean. Warming waters have also pushed cold-adapted species poleward, eroded the cold barrier between boreal and Arctic species, and induced rapid reorganisation of polar ecosystems. Studies increasingly indicate that the complex web of physical and biological connections that have fuelled these productive regions will falter without the strong regulating influence of cryospheric change. At the same time, the global demand for food is increasing, particularly the demand for highly nutritious marine protein, placing increasing importance on stabilising polar ecological systems and minimising climate change impacts and risks.

<span id="faq-ccp6.2-is-sea-ice-reduction-in-the-polar-regions-driving-an-increase-in-shipping-traffic"></span>
=== FAQ CCP6.2 | Is sea ice reduction in the polar regions driving an increase in shipping traffic? ===

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''The polar seas have captured the imagination of global nations for centuries for its natural resource, tourism, scientific, and maritime trade potential. As the polar regions are warming at two to three times the rate of the global average leading to rapid reductions in sea ice extent and thickness, international attention has been reinvigorated and investments are being made by Arctic and non-Arctic nations alike with a view to utilise newly accessible seaways. Between 2013 and 2019, ship traffic entering the Arctic grew by 25% and the total distance travelled increased by 75%. Similar shipping growth trends are evident in the Antarctic, albeit to a lesser extent. Expected growth in Arctic shipping will influence a suite of cascading environmental and cultural risks with implications for Indigenous Peoples.''

There has been debate among shipping stakeholders, rightsholders and experts about the extent to which climate change and sea ice change is directly influencing increases in shipping activity in the polar regions relative to other social, technological, political and economic factors such as commodity prices, tourism demand, global economic trends, infrastructure support and service availability. Understanding the connection between climate change and polar shipping activity will allow for more reliable projections of possible future traffic trends and will aid in identifying appropriate adaptation and infrastructure needs required to support future management of the industry. Recent studies have observed increasing statistical correlations between sea ice change and shipping trends in the polar regions, and many have concluded that although economic factors remain the main driver of shipping activities, followed by infrastructure availability, climate change does indeed play a varying but important role in influencing operator intentions. The ‘opening of polar seaways’ due to sea ice reduction is indeed ‘enabling’ opportunities for polar shipping among all types of vessels due to increasingly accessible areas that were previously covered by multi-year ice, but the extent to which climate change will specifically ‘drive’ an increase in shipping demand remains highly dependent on the vessel type and the reasons for operation. There are certain vessel types, such as those supporting international trade, mining operations or community re-supply, where analysis shows no correlation or weak correlations with sea ice change, suggesting that climate change is enabling these types of ships via increased open water areas and season lengths but that it is not necessarily driving demand. Conversely, there are certain vessel types, such as yachts and cruise ships, where correlations between sea ice change and traffic increases are stronger, and where there is evidence to suggest that these vessels are indeed driven to visit the polar regions because they perceive waterways as exotic and exciting due to being newly accessible or they want to have a Polar experience before it disappears or is irreversibly changed as is the case with last chance tourists. As sea ice recedes and polar shipping opportunities grow, there will be an increased need to better identify and implement Indigenous self-determined and equitable shipping governance frameworks that facilitate benefits and minimise risks.

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[[File:3b0291fb0f95acc5131b4fc275c8f150 IPCC_AR6_WGII_Figure_CCP6_FAQ_CCP6_2_1.png]]

'''Figure FAQ CCP6.2.1''' '''|''' '''Projected operational accessibility along Arctic maritime trade routes (Northwest Passage, Transpolar Route and Northern Sea Route) under future warming (left) and observed increases in commercial ship traffic along the routes from 2012 to 2019.'''

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<span id="ccp6.2.4-economic-activities"></span>
=== CCP6.2.4 Economic Activities ===

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Climate change presents significant risks to economic activities in the polar regions ( ''very high confidence'' ) and simultaneously enables development possibilities for fisheries (CCP6.2.3.3), agriculture (CCP6.2.3.2), the sharing and subsistence economy (CCP6.2.3.1) (SMCCP6.2) ( ''high confidence'' ), maritime trade (Box CCP6.1), natural resource development (CCP6.2.4.1) ( ''medium confidence'' ), tourism (CCP6.2.4.2) and transportation (including shipping) (CCP6.2.4.3; FAQ CCP6.2). Hundreds of billions of dollars are expected to be invested in the polar regions in the next several decades ( [[#Lloyd’s--2012|Lloyd’s, 2012]] ; [[#Barnhart--2016|Barnhart et al., 2016]] ; [[#Pendakur--2017|Pendakur, 2017]] ; [[#Tsukerman--2019|Tsukerman et al., 2019]] ), and, as this unfolds, there are opportunities to simultaneously implement adaptation strategies that support climate resilient development pathways in line with self-determination for Indigenous Peoples and local communities and locally derived visions of successful adaptation and development (CCP6.3.2, CCP6.4.3) ( [[#Jorgenson--2007|Jorgenson, 2007]] ; [[#Ritsema--2015|Ritsema et al., 2015]] ; [[#Ready--2017|Ready and Power, 2017]] ; [[#Larsen--2020|Larsen and Petrov, 2020]] ).

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<span id="ccp6.2.4.1-changing-access-to-natural-resources-with-consequences-for-safety-economic-development-and-climate-mitigation"></span>
==== CCP6.2.4.1 Changing access to natural resources with consequences for safety, economic development and climate mitigation ====

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Climate change is improving access to natural resources in the Arctic with consequences for human safety ( ''high confidence'' ), economic development ( ''very high confidence'' ) and global mitigation efforts ( ''medium confidence'' ). Reductions in sea ice combined with improved extraction and transportation technologies have increased accessibility to natural resources across the Arctic ( [[#Eliasson--2017|Eliasson et al., 2017]] ; [[#Dawson--2018b|Dawson et al., 2018b]] ; [[#Stephen--2018|Stephen, 2018]] ), a situation that could support continued global dependence on relatively cheap and abundant fossil fuels resources and contribute to further warming. By 2040 (RCP4.5) it is expected that sea ice will have receded enough to make gas production technologically feasible in the European off-shore Arctic ( [[#Petrick--2017|Petrick et al., 2017]] ). However, increased sea ice mobility, iceberg abundance, storm surge and surface wave action ( [[#Ng--2018|Ng et al., 2018]] ; [[#Howell--2019|Howell and Brady, 2019]] ; [[#Casas-Prat--2020|Casas-Prat and Wang, 2020]] ) will also increase risks to ships servicing mines in a region that already exhibits disproportionately high accident rates ( [[#Council%20of%20Canadian%20Academies--2016|Council of Canadian Academies, 2016]] ) (CCP6.3.1, Table CCP6.1). Season lengths for ship-based support to mines and extraction sites will increase with sea ice change, while access via ice roads will decrease with warming ( [[#Perrin--2015|Perrin et al., 2015]] ; [[#Council%20of%20Canadian%20Academies--2016|Council of Canadian Academies, 2016]] ; [[#Trofimenko--2017|Trofimenko et al., 2017]] ; [[#Southcott--2018|Southcott and Natcher, 2018]] ). By 2050, climate change impacts to the Tibbitt to Contwoyto Winter Road servicing mines in the northeastern region of the Northwest Territories, Canada could cost between $55 million to $213 million CAD to maintain for a shorter period of time than at present ( [[#Perrin--2015|Perrin et al., 2015]] ). Changes in submarine permafrost, critical to mining infrastructure, such as pipelines and offshore infrastructure ( [[#Bashaw--2016|Bashaw et al., 2016]] ; [[#Paulin--2016|Paulin and Caines, 2016]] ), are expected to increase production costs and impact safety for workers ( [[#Riedel--2017|Riedel et al., 2017]] ). By mid-century, regardless of emissions scenario, it is expected that risks from permafrost thaw will be disproportionately high for industrial infrastructure along major pipeline systems in Alaska and natural gas extraction areas in the Yamal-Nenets region in northwestern Siberia, Russia ( [[#Hjort--2018|Hjort et al., 2018]] ).

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<span id="ccp6.2.4.2-changing-demand-opportunities-and-risks-for-polar-tourism"></span>
==== CCP6.2.4.2 Changing demand, opportunities and risks for polar tourism ====

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Climate change has increased risks to, and demand for, polar tourism experiences related to increased maritime accessibility ( ''high confidence'' ), lengthening of warm weather season lengths ( ''very high confidence'' ) and development of a ‘last chance tourism market’ ( ''medium confidence'' ). Reductions in sea ice extent have facilitated increased access for polar cruising ( [[#Dawson--2018b|Dawson et al., 2018b]] ; [[#Stewart--2020|Stewart et al., 2020]] ). Demand for Arctic cruises has increased by 20.5% over the past 5 years and resulted in 27.2 million passengers in 2018 ( [[#Shijin--2020|Shijin et al., 2020]] ). In the Antarctic, tourist numbers increased by 27% from 1992 to 2018 and attracted 75,000 visitors in 2019–2020 (IAATO, 2020; [[#Shijin--2020|Shijin et al., 2020]] ), making it the largest economic sector in the entire region ( [[#Stewart--2020|Stewart et al., 2020]] ). The recent increase in polar tourism is due in part to the development of a niche market called ‘last chance tourism’, which involves explicitly marketing vulnerable or vanishing destinations or features (i.e., glaciers, polar bears, landscapes) and encouraging tourists to see them ‘before they are gone’ ( [[#Dawson--2018a|Dawson et al., 2018a]] ; [[#Groulx--2019|Groulx et al., 2019]] ). However, tourism development opportunities will also contend with ongoing risks related to the coronavirus disease 2019 (COVID-19) pandemic, which halted tourism globally in 2020–2021 ( [[#Frame--2020|Frame and Hemmings, 2020]] ; [[#Lorenzo--2020|Lorenzo et al., 2020]] ), as well as those related to increased climatic risks limiting participation and reducing safety and security. By 2100, under RCP8.5, snow cover season length suitable for winter recreational activities is projected to decrease by 21–49% in West Greenland ( [[#Schrot--2019|Schrot et al., 2019]] ). Reduced sea ice and snow cover creates hazards for and could limit dog sledding, cross country skiing, snowmobiling and floe edge tours, with limited adaptation strategies available for low-elevation areas ( [[#Stephen--2018|Stephen, 2018]] ; [[#Palma--2019|Palma et al., 2019]] ).

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<span id="ccp6.2.4.3-risks-and-opportunities-in-transportation-systems"></span>
==== CCP6.2.4.3 Risks and opportunities in transportation systems ====

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Climate hazards create risks to transportation sectors with consequences for human safety ( ''very high confidence'' ), security ( ''low confidence'' ) and economic development ( ''high confidence'' ). Remote polar regions are highly reliant on transportation systems (air, road, sea) to support and service communities (Arctic) and scientific stations (Antarctic and Arctic). Changes in permafrost, snow, ice and precipitation patterns have increased the risk of rail infrastructure and of using permanent roads and semi-permanent trails that service Antarctic research stations, connect Arctic communities and support Indigenous food harvesting activities ( [[#Calmels--2015|Calmels et al., 2015]] ; [[#Council%20of%20Canadian%20Academies--2016|Council of Canadian Academies, 2016]] ; [[#Ford--2019|Ford et al., 2019]] ; [[#Stewart--2020|Stewart et al., 2020]] ). Warming temperatures have particularly decreased the reliability, safety level and season length of winter ice roads ( [[#Perrin--2015|Perrin et al., 2015]] ; [[#Council%20of%20Canadian%20Academies--2016|Council of Canadian Academies, 2016]] ; [[#Gädeke--2021|Gädeke et al., 2021]] ) in the northern Baltic (Finland) ( [[#Kiani--2018|Kiani et al., 2018]] ), James Bay (Canada) ( [[#Hori--2018a|Hori et al., 2018a]] ; [[#Hori--2018b|Hori et al., 2018b]] ) and Yakutia (Russia) ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ). Dog sled travel in northwest Greenland has experienced shorter season lengths ( [[#Nuttall--2020|Nuttall, 2020]] ), Alaskan whale hunters have had difficulty finding suitable ice for safe harvest activities ( [[#Huntington--2016|Huntington et al., 2016]] ; [[#Nyland--2017|Nyland et al., 2017]] ), and unpredictability in break-up and freeze-up of sea ice has compromised safe travel to and from culturally significant hunting and camping areas in Canada ( [[#Dawson--2020|Dawson et al., 2020]] ; [[#Simonee--2021|Simonee et al., 2021]] ) and northeast Siberia ( [[#Ksenofontov--2017|Ksenofontov et al., 2017]] ; [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ). Fog ( ''low confidence'' ) and an increase in precipitation falling as ice pellets or hail ( ''high confidence'' ) ( [[#Kochtubajda--2017|Kochtubajda et al., 2017]] ) is expected to continue to cause operational delays and create safety issues for aviation in the polar regions ( [[#Debortoli--2019|Debortoli et al., 2019]] ).

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<span id="box-ccp6.2-arctic-indigenous-self-determination-in-climate-change-assessment-and-decision-making"></span>
=== Box CCP6.2 | Arctic Indigenous Self-determination in Climate Change Assessment and Decision Making ===

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Similar to Indigenous Peoples globally (Cross-Chapter Box INDIG in Chapter 18), climate change vulnerability for Arctic Indigenous Peoples is often rooted in colonialism, which has led to land dispossession and displacement, carbon-intensive economies, discrimination, racism, marginalisation and social, cultural and health inequities ( [[#Whyte--2016|Whyte, 2016]] ; [[#Whyte--2017|Whyte, 2017]] ; [[#Whyte--2019|Whyte et al., 2019]] ; [[#Chakraborty--2021|Chakraborty and Sherpa, 2021]] ). Therefore, effective responses to climate change risks for Indigenous Peoples are self-determined and underpinned by Indigenous knowledge (IK) ( ''very high confidence'' ).

IK systems are diverse among and within Arctic Indigenous Peoples, and reflect deep and rich knowledge that situates and contextualises values, traditions, governance and practical ways of adapting to the ecosystem over millennia ( [[#Raymond-Yakoubian--2017|Raymond-Yakoubian et al., 2017]] ; [[#Brattland--2018|Brattland and Mustonen, 2018]] ). IK is a valuable source of knowledge; a method to detect change, evaluate risk and inform adaptation approaches; and a cultural ecological service ( [[#Brattland--2018|Brattland and Mustonen, 2018]] ; [[#Crate--2019|Crate et al., 2019]] ; [[#Meredith--2019|Meredith et al., 2019]] ) that is critical for decision making ( [[#Mustonen--2016|Mustonen and Mustonen, 2016]] ; [[#Huntington--2017|Huntington et al., 2017]] ). For instance, Kalaallit knowledge in Greenland has been used to detect and attribute long-term (over 50 years) marine change that reaches beyond scientific instrumental data ( [[#Mustonen--2018b|Mustonen et al., 2018b]] ).

This Box was written by Indigenous authors, recognising that IK and LK are intellectual property (Cross-Chapter Box INDIG in Chapter 18), alleviating the risk of this knowledge being misinterpreted ( [[#David-Chavez--2018|David-Chavez and Gavin, 2018]] ; [[#Hughes--2018|Hughes, 2018]] ; [[#Raymond-Yakoubian--2018|Raymond-Yakoubian and Daniel, 2018]] ) and acknowledging that meaningful inclusion of Indigenous Peoples strengthens and supports Indigenous self-determination ( [[#ITK--2019|ITK, 2019]] ). Self-determination signifies and values the capacity and decisions made by these peoples in their own right and from their own autonomous cultural positioning. Following the format used in SROCC, this Box prioritises Indigenous voices by presenting climate change assessments premised on IK and written by Indigenous Peoples.

'''Climate Change, Nomadic Lifestyles and Preservation of Traditions'''
Perspectives from the Yukaghir Council of Elders and Russian Association of Indigenous Peoples, Russia

Climate change threatens reindeer herding, hunting, fishing and gathering, which form the basis of Siberian Indigenous societies. Nomadic herding lifestyle is premised on IK which has accumulated over millennia. IK, including the ability to predict weather, has played a substantial role in the adaptation to the extreme conditions. According to [[#Shadrin--2021|Shadrin (2021)]] , present, rapid changes are changing Indigenous concepts of reality; they are increasingly finding themselves in situations where their experience and knowledge cannot help them. An Elder in Northeast Siberia explained that ‘nature does not trust us anymore’ ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ).

A major problem for nomadic reindeer herding is the degradation of reindeer pastures ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ). The expansion of willows and shrubs into the tundra has resulted in losses of pastures. In other nomadic communities, these changes have led to the expansion of moose into tundra area and effects of reindeer populations, as well as changes in wild reindeer migration routes leading to the destruction of domestic reindeer pastures ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ).

Due to the steady changes in precipitation in recent years, a deeper than usual snow cover has formed in Northeast Siberia ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ). This alters the capacity of reindeer to access lichen, their primary food source. Late onset of cold weather has led to difficulties in the herds moving to their winter pastures. In the summer, increased rainfall has led to waterlogging of low-lying pastures. The most important challenge is the instability of the weather ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ). This includes frequent, never-before-seen warming, combined with rains in the late winter and early spring. Sharp temperature drops of over 30°C occurring within a few hours lead to formation of an ice crust on the ground which becomes a challenge for reindeer, especially in autumn, and are becoming more frequent. Furthermore, the number of summer storms and rapid cooling accompanied with snowfall during July has increased. Using IK to predict weather is the basis of effective survival. It has become extremely difficult due to the unprecedented fast changing conditions ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ) ( [[#Shadrin--2021|Shadrin, 2021]] ). All of these events lead to increased risks in the lives of Indigenous Peoples ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ).

Climate change impacts Indigenous Peoples’ health. Degradation of the quality of surface waters has increased, resulting from new floods and the thawing of permafrost, which increases risk of gastrointestinal diseases (CCP6.2.8). The 2007 flood on Alazaya River was of special importance and was locally identified to have produced the first regional ‘climate refugees’ ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ). Warming has expanded the distribution of new disease-carrying insects and ticks into new territories ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ). Ancient cemeteries and campsites, as well as the burial sites of reindeer, become dangerous as permafrost thaws and coastal erosion proceeds.

Traditional food security is under threat. Permafrost-based storage facilities have deteriorated (CCP6.2.6) ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ). There is an increase in the number of people who are forced to abandon the consumption of raw fish. As a result, the likelihood of losing cultural traditions is growing. These combined climate change impacts result in loss of IK and nomadic lifestyles, thus losing important aspects of their identity as distinct Indigenous Peoples ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ).

'''Climate Change Impacts on Sámi Women'''
Perspectives from Sámi in Finland

[[#Feodoroff--2021|Feodoroff (2021)]] stresses that many Sámi women are central to Indigenous-led adaptation. Indigenous women use their bodies as gauges of change. For example, the restoration work in Näätämöjoki River in Finland ( [[#Ogar--2020|Ogar et al., 2020]] ; [[#Feodoroff--2021|Feodoroff, 2021]] ) is based on the knowledge of traditional fishers and reindeer herders. IK and Western science offer possibilities to reflect on changes that the waters in Indigenous bodies have known of events of the past ( [[#Feodoroff--2021|Feodoroff, 2021]] ). Changes in temperature, pain and the gradual passing of pain, waves and intrusions within Indigenous bodies are knowledges that are difficult to communicate according to [[#Feodoroff--2021|Feodoroff (2021)]] . Women are sensitive to receiving messages from their home environments. [[#Feodoroff--2021|Feodoroff (2021)]] stresses that Indigenous conservation work is a bodily commitment. This realisation is linked with difficult questions of what or who controls Indigenous bodies. [[#Feodoroff--2021|Feodoroff (2021)]] links present change with lingering impacts of global environmental damage that has not been dealt with or addressed. It may lead to real pain in Indigenous bodies and minds, causing feelings of being nauseated and ultimately causing fade-out, wilt, withering and extinguishment of Indigenous Peoples.

'''Adaptation Successes Underpinned by Inuit Knowledge'''
Perspectives from Inuit Circumpolar Council

Inuit have survived and thrived in Inuit Nunaat, their homelands, for millennia. In an environment that presents unique challenges, they have cultivated resourceful and innovative approaches tailored to their surroundings. Their values and knowledge guide their relationships with all that is within the Arctic, and this has informed their decisions and management practices that continue to be in place today ( [[#Inuit%20Circumpolar%20Council%20Alaska--2020|Inuit Circumpolar Council Alaska, 2020]] ). They are experts in adaptation. Now more than ever, in the time of anthropogenic climate change, living in the fastest warming region on the planet requires this expertise and capacity.

The extraordinary developments in the field of IK have crystallised the main tenant of interaction with the natural world that is ‘integral to a cultural complex that also encompasses language, systems of classification, resource use practices, social interactions, ritual and spirituality’ (UNESCO, 2017). Inuit have used their knowledge of the land and coastal seas to design technology, monitoring systems (Atlas of Community-Based Monitoring in a Changing Arctic, 2021) and new hunting routes that respond to the changes they face ( [[#Inuit%20Circumpolar%20Council--2017|Inuit Circumpolar Council, 2017]] ; [[#Nunavut%20Climate%20Change%20Center--2018|Nunavut Climate Change Center, 2018]] ; [[#SIKU--2020|SIKU, 2020]] ). Such examples of ‘adaptation success’ across Inuit Nunaat have been showcased and celebrated nationally and internationally (Youth Climate Report, 2019), and all are underpinned by Inuit knowledge and pivot on their right to self-determination. This is also embodied, for example, in Canada; the National Inuit Climate Change Strategy outlines the collective Canadian Inuit plan for climate action, centring on Inuit-determined priorities to protect their culture, language and way of life, and guiding partners in how to work with Inuit on implementing this strategy ( [[#ITK--2019|ITK, 2019]] ). Their action on adaptation also spans scales from local to international. As far back as 1977, Inuit have been organised and involved at the international level. Inuit were present at the Rio Earth Summit and have participated in diverse but interrelated United Nations conventions to protect their homelands (e.g., UNFCCC, CBD, Stockholm Convention). This history gives us unique insight and positions us as both leaders and partners with the ability to engage directly with governments, business and others.

However, while Inuit are often recognised as leaders in adaptation, too often the academic literature ends there, citing ‘successful Inuit-led adaptation to climate change’ but not going further to explore towards what end this adaptation is designed. We have demonstrated leadership and set an example for the world in how to respond to change, but successful adaptation is not enough; it is not the end goal.

Central to their significant capacity to adapt is that it is done in recognition of the need to move beyond adaptation. Indeed, Inuit-led adaptation action is founded on the intention of contributing to and moving towards reformation and eventual transformation of systems to create a ‘climate resilient’ Arctic. This concept has surfaced in academic climate change literature and discussion and has begun to filter into the climate policy arena, especially within the context of the current COVID-19 pandemic that challenges us all to think about our world differently. With acknowledgement that reform and transformation is needed, the question remains, ‘What does this look like?’

Inuit have an answer. System reform and transformation is grounded in self-determination. It is based in a human rights framework and rooted in IK and culture. It recognises and respects interconnectedness and builds this into solutions. It demands collaboration and true partnership towards action. And it comes from thinking big and across scales. Shaping this change calls for willingness and support to rethink the current economic and governance models that have failed us. For example, decentralising governance and management, while it remains largely unconventional, has been shown to create some of the strongest systems we have. This is, in large part, due to the way in which decentralisation places more value and responsibility on the ‘self’ in self-determination. Decentralised processes in the Arctic have IK holders playing a key and lead role in determining, defining and deciding how to work towards positive change.

Across Inuit Nunaat, examples of direct management and control over lands, territories and resources have demonstrated that working from what is happening on the ground throughout their homelands, from their priorities and interests, has served to strengthen the health of their environment and their communities. For example, a comparative analysis on factors supporting and impeding Inuit food sovereignty between Alaska and the Inuvialuit Settlement Region found that the difference in outcomes within these regions is dependent on explicit respect for and recognition of the Inuit right of self-determination ( [[#Inuit%20Circumpolar%20Council%20Alaska--2020|Inuit Circumpolar Council Alaska, 2020]] ). Furthermore, a new agreement achieved in Nunavut by the Qikiqtani Inuit Association related to the marine environment touted as an exemplary model for marine management is rooted in Inuit-determined structures and policies, and manifested by Inuit themselves ( [[#QIA--2019|QIA, 2019]] ).

Emphasis on decentralised management and substantial funding to do so at the grassroots level has been recognised by the IPCC previously in the SROCC. Ultimately, going beyond reform to system transformation requires, as Oren Lyons has stated, ‘value change for survival’ ( [[#Lyons--2020|Lyons, 2020]] ). Valuing decentralisation, self-determination, Inuit knowledge, interconnectedness—core values held by Inuit—can move us in a climate-resilient direction.

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<span id="ccp6.2.5-arctic-settlements-and-communities"></span>
=== CCP6.2.5 Arctic Settlements and Communities ===

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Polar settlements range from large well-serviced cities such as Tromsø, Murmansk and Reykjavik, to remote fly-in Indigenous communities, to scientific outposts and research stations. Polar settlements are at significant risk from climate change through shoreline erosion, permafrost thaw and flooding ( ''high confidence'' ) (CCP6.2.2). Opportunities for community development in small communities are underestimated as they are emergent and unknown ( ''highly likely'' ) (CCP6.2.5).

Degradation of ice-rich permafrost can threaten the structural stability and functional capacities of community-based infrastructure (i.e., airports and roads; CCP6.2.5) and can have implications for local economies with coupled impacts for local livelihoods, health and well-being (CCP6.2.5, CCP6.2.6) ( ''high confidence'' ). For instance, in Canada, infrastructure damage from permafrost instability caused temporary closures of schools in Yukon, permafrost degradation contributed to runway damage at Iqaluit International Airport in Nunavut, and flooding from heavy rains resulted in thermal erosion of river banks that interrupted water and sewage service in Nunavut ( [[#Oldenborger--2015|Oldenborger and LeBlanc, 2015]] ; [[#Council%20of%20Canadian%20Academies--2016|Council of Canadian Academies, 2016]] ; [[#Lemmen--2016|Lemmen et al., 2016]] ). In northeast Siberia, the floods of Alazaeya River attributed to thawing permafrost have severely affected Andreyushkino in Yakutia ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ).

By 2050, 69% of fundamental human infrastructure in the Arctic is projected to be at risk under an RCP4.5 scenario, including more than 1200 settlements and 36,000 buildings, leaving 4,000,000 people living in areas with high potential for thaw ( [[#Hjort--2018|Hjort et al., 2018]] ). Widespread permafrost thaw could increase the cost of infrastructure lifecycle replacement by 27% by mid-century under RCP8.5 ( [[#Suter--2019|Suter et al., 2019]] ). Northern Canada and Western Siberia are at particularly high risk, which are projected to cost additional annual spending of over 1% of annual gross regional product to maintain existing infrastructure ( [[#Suter--2019|Suter et al., 2019]] ). For instance, under an RCP8.5 scenario, climate change could affect over 19% of structures and infrastructure assets in Russia, which would cost an estimated $84.4 billion USD to mitigate damages ( [[#Streletskiy--2019|Streletskiy et al., 2019]] ). Fifty-four percent of residential buildings are projected to be affected by significant permafrost degradation by the mid-century, costing an additional estimated $52.6 billion USD ( [[#Streletskiy--2019|Streletskiy et al., 2019]] ). Sea level rise (SLR) and reduced sea ice protection is projected to compound permafrost thaw damages, including low lying coasts (e.g., along southern Beaufort Sea), low-lying barrier islands (e.g., along Chukchi Sea), and deltas (e.g., Mackenzie, Lena) ( [[#Fritz--2017|Fritz et al., 2017]] ; [[#Lantz--2020|Lantz et al., 2020]] ). In Alaska, proactive adaptation was substantially cost-saving (reducing costs by $2.9 billion USD for RCP8.5 and $2.3 billion USD for RCP4.5), highlighting the financial benefit of investing in adaptation now ( [[#Melvin--2017|Melvin et al., 2017]] ). Permafrost damage and SLR may result in tipping points, leaving some communities no longer habitable. In Alaska, USA, many communities at risk of flooding and storm surges are already engaged in community-led relocation planning processes (e.g., Shishmaref) ( [[#Melvin--2017|Melvin et al., 2017]] ; [[#Farbotko--2020|Farbotko et al., 2020]] ; [[#Rosales--2021|Rosales et al., 2021]] ).

Climate change has important intangible loss and damage implications in the Arctic, with negative impacts ranging from livelihoods to spirituality to solastalgia (i.e., distress caused by environmental change) ( [[#Cunsolo--2018|Cunsolo and Ellis, 2018]] ; [[#Middleton--2020b|Middleton et al., 2020b]] ; [[#Sawatzky--2020|Sawatzky et al., 2020]] ; [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ). Permafrost thaw, SLR and reduced sea ice protection also presents risk to sociocultural assets, including heritage sites in all Arctic regions ( ''very high confidence'' ) ( [[#Friesen--2015|Friesen, 2015]] ; [[#Hollesen--2016|Hollesen et al., 2016]] ; [[#Radosavljevic--2016|Radosavljevic et al., 2016]] ; [[#O’Rourke--2017|O’Rourke, 2017]] ; [[#Hillerdal--2019|Hillerdal et al., 2019]] ; [[#Fenger-Nielsen--2020|Fenger-]] [[#Nielsen--2020|Nielsen et al., 2020]] ; [[#Jensen--2020|Jensen, 2020]] ). A large number of archaeological sites are at risk from climate change in southwest Greenland; Yukon’s Beaufort coast, Canada; and Auyuittuq National Park Reserve, Nunavut, Canada ( [[#Westley--2011|Westley et al., 2011]] ; [[#Hollesen--2018|Hollesen et al., 2018]] ; [[#Irrgang--2019|Irrgang et al., 2019]] ; [[#Fenger-Nielsen--2020|Fenger-]] [[#Nielsen--2020|Nielsen et al., 2020]] ). Siberian nomadic reindeer herding and fishing livelihoods are vulnerable to permafrost thaw, which alters northern landscapes and lakes, as well as rain-on-snow events, and rapidly changes landscapes and terrestrial and aquatic habitats ( [[#Mustonen--2016|Mustonen and Mustonen, 2016]] ; [[#Brattland--2018|Brattland and Mustonen, 2018]] ; [[#Mustonen--2020|Mustonen and Huusari, 2020]] ) (CCP6.2.2). The intangible loss and damage to nomadic cultures could cascade to losses of identity and social challenges (CCP6.2.6; Chapter 13).

<div id="box-ccp6.1" class="h2-container box-container"></div>

'''Box CCP6.1 | Climate Change and the Emergence of Future Arctic Maritime Trade Routes'''
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Discovering a viable maritime trade route linking the Atlantic and Pacific oceans through the Arctic has captured the collective global imagination for centuries ( [[#Bockstoce--2018|Bockstoce, 2018]] ). Geographically shorter than southern trade routes via the Panama and Suez Canals, the Arctic presents the possibility for more economical and timely commercial trade, but has historically been limited by thick multi-year ice and other navigational challenges. Amplified warming in the Arctic has caused September sea ice extent to decline at a rate of −13% per decade ( [[#Serreze--2019|Serreze and Meier, 2019]] ) and reduced sea ice thickness by 66% (2 m) between 1958–1976 and 2011–2018 ( [[#Kwok--2018|Kwok, 2018]] ). Regardless of mitigation efforts, it is expected that before mid-century the Arctic will be seasonally ice free for the first time in 2,600,000 years (defined as &lt;1,000,000 km '''2''' ) ( [[#Knies--2014|Knies et al., 2014]] ; [[#SIMIP%20Community--2020|SIMIP Community, 2020]] ; [[#Fox-Kemper--2021|Fox-Kemper et al., 2021]] ; [[#Lee--2021|Lee et al., 2021]] ) and will make Arctic maritime trade a reality ( [[#Eguíluz--2016|Eguíluz et al., 2016]] ; [[#Melia--2016|Melia et al., 2016]] ; [[#Pizzolato--2016|Pizzolato et al., 2016]] ; [[#Bennett--2020|Bennett et al., 2020]] ; [[#Wei--2020|Wei et al., 2020]] ).

There are three identified trade routes in the Arctic: Northern Sea Route (NSR), Northwest Passages (NWP) and the Transpolar Sea Route (TSR). Over the last decade, economic trends and reductions in sea ice have facilitated significant increases in ship traffic in the NSR ( [[#Aksenov--2017|Aksenov et al., 2017]] ; [[#Li--2020|Li et al., 2020]] ), including a 79% increase in total transit tonnage from 2010 to 2017 ( [[#Babin--2020|Babin et al., 2020]] ) related mostly to domestic resource development. Relative to an early 21st century baseline, it is expected that the NSR will become 18% more accessible by mid-century ( [[#Stephenson--2013|Stephenson et al., 2013]] ) and could be navigable even for non-ice strengthened vessels for 101–118 days annually by 2050 and 125–192 days by 2100 ( [[#Khon--2017|Khon et al., 2017]] ). The NWP has experienced a tripling of km travelled by ships since 1990, attributed mostly to resource extraction and increases in tourism opportunities ( [[#Johnston--2017|Johnston et al., 2017]] ; [[#Dawson--2018a|Dawson et al., 2018a]] ). The NWP could become 30% more accessible by 2050 compared with current conditions ( [[#Stephenson--2013|Stephenson et al., 2013]] ). Before 4°C global warming above pre-industrial, re-supply vessels (Polar Class 7) in the western NWP could gain an additional month of operating time, whereas the eastern NWP could gain just 2 weeks ( [[#Mudryk--2021|Mudryk et al., 2021]] ) due to the dynamic import of mobile and hazardous ice from the Arctic Ocean ( [[#Haas--2015|Haas and Howell, 2015]] ; [[#Howell--2019|Howell and Brady, 2019]] ). Comparatively, the TSR has historically only been viable for nuclear icebreakers, submarines, and occasional military and scientific activity due to thick multi-year ice regimes ( [[#Bennett--2020|Bennett et al., 2020]] ). However, this most sought-after route offers the greatest reduction in sailing times compared with southern routes (19–24 days) of all Arctic Sea routes and could be 56% more accessible by mid-century compared with current conditions ( [[#Stephenson--2013|Stephenson et al., 2013]] ; [[#Melia--2016|Melia et al., 2016]] ).

<div id="_idContainer023" class="Figure"></div>

[[File:f83b5e211c8d5042800e0d932d670841 IPCC_AR6_WGII_Figure_CCP6_Box_CCP6_1_1.png]]

'''Figure Box CCP6.1.1 |''' '''Arctic trade routes and projected operations related to sea ice loss.'''

Growth in Arctic maritime trade will result in increased emission of black carbon ( [[#Stephenson--2018|Stephenson et al., 2018]] ; [[#Zhang--2019|Zhang et al., 2019]] ; [[#Wang--2021|Wang et al., 2021]] ), increases in ship-source underwater noise impacts on marine mammals ( [[#Halliday--2017|Halliday et al., 2017]] ), higher rates of accidents and incidents among vessels from increasing mobile sea ice and newly accessible ice-free waters that lack charting ( [[#Haas--2015|Haas and Howell, 2015]] ; [[#Howell--2019|Howell and Brady, 2019]] ), impacts to cultural sustainability for Indigenous Peoples ( [[#Olsen--2019|Olsen et al., 2019]] ; [[#Dawson--2020|Dawson et al., 2020]] ) ( ''high confidence'' ), the potential for the introduction and propagation of invasive species ( [[#Chan--2019|Chan et al., 2019]] ; [[#Rosenhaim--2019|Rosenhaim et al., 2019]] ), and sovereignty tensions with implications for global geopolitics ( [[#Drewniak--2018|Drewniak et al., 2018]] ) ( ''medium confidence'' ). Globalisation and the almost universal adherence to economic growth models among nations will continue to fuel maritime trade (Box 14.5). As sea ice decreases facilitates growth in Arctic maritime trade and transportation specifically, adaptation strategies designed to facilitate mitigation co-benefits and that target the cascading implications and double exposure of climate change and Arctic shipping impacts will be essential in reducing risks ( [[#Ng--2018|Ng et al., 2018]] ; [[#Pirotta--2019|Pirotta et al., 2019]] ; [[#Bennett--2020|Bennett et al., 2020]] ; [[#Zeng--2020|Zeng et al., 2020]] ). Electric and solar powered vessels, new engine and emission reduction technologies, investment in wind, water, ice and climate forecasting technologies and services ( [[#Haavisto--2020|Haavisto et al., 2020]] ; [[#Stewart--2020|Stewart et al., 2020]] ; [[#Simonee--2021|Simonee et al., 2021]] ), and efforts by the International Maritime Organization to reduce sulphur and the use of heavy fuel oils ( [[#PAME--2020|PAME, 2020]] ; [[#van%20Luijk--2020|van Luijk et al., 2020]] ) could play a key role in limiting emissions and reducing risks related to the environmental and cultural impacts of fuel spills in ice-infested Arctic waters. The development of low-impact shipping corridors ( [[#Chénier--2017|Chénier et al., 2017]] ; [[#Dawson--2020|Dawson et al., 2020]] ) and multi-lateral agreements such as those implemented by the Arctic Council and Indigenous Peoples’ organisations on joint search and rescue ( [[#Arctic%20Council--2011|Arctic Council, 2011]] ) and shared spill responsibilities ( [[#Arctic%20Council--2013|Arctic Council, 2013]] ) represent important co-governance efforts that will be increasingly important in the future owing to projected climate-related risks.

<span id="faq-ccp6.3-how-have-arctic-communities-adapted-to-environmental-change-in-the-past-and-will-these-experiences-help-them-respond-now-and-in-the-future"></span>
=== FAQ CCP6.3 | How have arctic communities adapted to environmental change in the past and will these experiences help them respond now and in the future? ===

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''For thousands of years, Arctic Indigenous Peoples and local communities have survived several major changes to the ecosystems on which they rely; however, the present changes in climate are more challenging than pre- and early historic changes in the Arctic, and polar communities will now face new unprecedented risks.''

The challenges for responding to present change are due to the multiple imposed and simultaneous drivers combined with elimination and/or removal of endemic capacity to respond in culturally and locally appropriate ways. Adapting in the past may therefore inform and produce novel solutions for the present and convey baselines of important contextual information on significance of change. Arctic communities, especially Indigenous Peoples, have been marginalised in terms of their autonomous responses spaces and self-assessment that could be made without external pressures. Therefore, to increase the possibility of community-led adaptation, colonialism and the resultant lack of upheld rights, resources and equity need to be solved simultaneously with the present climate change impacts. New research, governance, policy and collaborations are needed to effectively adapt to risks that are projected to emerge in the polar regions as a result of rapid climate change.

<div id="CCP6.2.6" class="h2-container"></div>

<span id="ccp6.2.6-human-health-and-wellness-in-the-arctic"></span>
=== CCP6.2.6 Human Health and Wellness in the Arctic ===

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Climate change continues to have wide-ranging physical human health risks in the Arctic, particularly for Indigenous Peoples ( ''high confidence'' ); however, future projections of physical risks are nascent. Climate change has already challenged food and nutritional security (CCP6.2.5). Climate change also creates safety concerns for those who access the land, ice and water for food, cultural and recreational purposes, with changing environmental conditions linked to injury and death ( [[#Durkalec--2014|Durkalec et al., 2014]] ; [[#Clark--2016a|Clark et al., 2016a]] ; [[#Clark--2016b|Clark et al., 2016b]] ; [[#Driscoll--2016|Driscoll et al., 2016]] ; [[#Brattland--2018|Brattland and Mustonen, 2018]] ). Foodborne disease risks are expected to increase in the Arctic, with warming temperatures linked to increased risk of microbial contamination of locally harvested foods ( [[#Grjibovski--2013|Grjibovski et al., 2013]] ; [[#Harper--2015|Harper et al., 2015]] ), chemical contamination of locally harvest foods ( [[#Hansen--2015|Hansen et al., 2015]] ; [[#Long--2015|Long et al., 2015]] ; [[#Alava--2017|Alava et al., 2017]] ), compromised structural integrity and utility of ice cellars used to store locally harvested meat ( [[#Nyland--2017|Nyland et al., 2017]] ; [[#Markon--2018|Markon et al., 2018]] ), and new challenges to traditional food preparation techniques ( [[#Shadrin--2021|Shadrin, 2021]] ). Waterborne disease risks have increased, with decreased drinking water quality and quantity, water treatment infrastructure failures and new waterborne pathogens emerging in the Arctic ( [[#Berner--2016|Berner et al., 2016]] ; [[#Thivierge--2016|Thivierge et al., 2016]] ; [[#Markon--2018|Markon et al., 2018]] ; [[#Yoder--2018|Yoder, 2018]] ; [[#Masina--2019|Masina et al., 2019]] ; [[#Sachal--2019|Sachal et al., 2019]] ; [[#Harper--2020|Harper et al., 2020]] ; [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ). Emerging environmental exposures to pathogens is also a concern. In 2016, a Nenets boy and over 200,000 reindeer died from anthrax linked to warming environments ( [[#Ezhova--2021|Ezhova et al., 2021]] )—a risk which is projected to increase with climate change ( [[#Liskova--2021|Liskova et al., 2021]] ). Thawing permafrost increases smallpox risk in former nomadic campsites and graveyards ( [[#Mustonen--2021|Mustonen and]] [[#Shadrin--2021|Shadrin, 2021]] ; [[#Shadrin--2021|Shadrin, 2021]] ). Arctic health systems—which are often already stressed—will be further challenged by climate change ( [[#Harper--2015|Harper et al., 2015]] ; [[#Clark--2017|Clark and Ford, 2017]] ), especially in conjunction with other system shocks (e.g., COVID-19) (Cross-Chapter Box COVID in Chapter 7) ( [[#Zavaleta-Cortijo--2020|Zavaleta-Cortijo et al., 2020]] ). While physical health impacts have been observed, research examining future health projections or evaluating the efficacy of health adaptations is rare ( [[#Dobson--2015|Dobson et al., 2015]] ; [[#Harper--2020|Harper et al., 2020]] ; [[#Harper--2021|Harper et al., 2021]] ).

Climate change has negative, widespread and cumulative impacts on mental health in the Arctic, particularly for Indigenous Peoples ( ''very high confidence'' ) (Figure CCP6.3). Climate-sensitive mental health outcomes are complex, overlapping and interrelated, and have multiple direct and indirect pathways stemming from acute (e.g., major storms, flooding, wildfires) and chronic (e.g., temperature increases, sea ice loss, permafrost thaw) environmental conditions, and resulting disruptions to livelihoods, culture, food systems, social connections, health systems and economies ( [[#Cunsolo%20Willox--2013a|Cunsolo Willox et al., 2013a]] ; [[#Cunsolo%20Willox--2013b|Cunsolo Willox et al., 2013b]] ; [[#Cunsolo%20Willox--2014|Cunsolo Willox et al., 2014]] ; [[#Beaumier--2015|Beaumier et al., 2015]] ; [[#Durkalec--2015|Durkalec et al., 2015]] ; [[#Hamilton--2016|Hamilton et al., 2016]] ; [[#Clayton--2017|Clayton et al., 2017]] ; [[#Dodd--2018|Dodd et al., 2018]] ; [[#Jaakkola--2018|Jaakkola et al., 2018]] ; [[#Markon--2018|Markon et al., 2018]] ; [[#ITK--2019|ITK, 2019]] ; [[#Minor--2019|Minor et al., 2019]] ; [[#Middleton--2020a|Middleton et al., 2020a]] ; [[#Middleton--2020b|Middleton et al., 2020b]] ; [[#Feodoroff--2021|Feodoroff, 2021]] ).

<div id="_idContainer023" class="Figure"></div>

[[File:021ad55e0b030cdb7a3e982f3dd1bef3 IPCC_AR6_WGII_Figure_CCP6_003.png]]

'''Figure CCP6.3 |''' '''The pathways through which climate change impacts mental and emotional health in the Arctic.'''

Negative mental health outcomes from climate change include: emotional reactions (e.g., sadness, fear, anger, distress and anxiety); psychosocial outcomes (e.g., depression, post-traumatic stress disorder and generalised anxiety); experiences with grief and loss (i.e., ecological grief); increased drug and alcohol usage, family stress and domestic violence; increased suicide ideation and suicides; loss of cultural knowledge and continuity, disruptions to intergenerational knowledge transfer; and deterioration and loss of place-based identities and connections (i.e., solastalgia) ( [[#Cunsolo%20Willox--2013a|Cunsolo Willox et al., 2013a]] ; [[#Cunsolo%20Willox--2013b|Cunsolo Willox et al., 2013b]] ; [[#Cunsolo%20Willox--2014|Cunsolo Willox et al., 2014]] ; [[#Durkalec--2015|Durkalec et al., 2015]] ; [[#Harper--2015|Harper et al., 2015]] ; [[#Cunsolo--2018|Cunsolo and Ellis, 2018]] ; [[#Hayes--2018|Hayes et al., 2018]] ; [[#Jaakkola--2018|Jaakkola et al., 2018]] ; [[#Markon--2018|Markon et al., 2018]] ; [[#Minor--2019|Minor et al., 2019]] ; [[#Middleton--2020a|Middleton et al., 2020a]] ; [[#Feodoroff--2021|Feodoroff, 2021]] ).

The negative mental health impacts from climate change are amplified among those most reliant on the environment for subsistence and livelihoods, those who already face chronic physical or mental health issues, and those facing socioeconomic inequities and marginalisation, particularly for Indigenous Peoples ( ''high confidence'' ). These climate change related mental health impacts are unequally distributed ( [[#Cunsolo%20Willox--2014|Cunsolo Willox et al., 2014]] ; [[#Minor--2019|Minor et al., 2019]] ), and may vary by gender ( [[#Beaumier--2015|Beaumier et al., 2015]] ; [[#Harper--2015|Harper et al., 2015]] ; [[#Feodoroff--2021|Feodoroff, 2021]] ) and age ( [[#Petrasek%20MacDonald--2013|Petrasek MacDonald et al., 2013]] ; [[#Ostapchuk--2015|Ostapchuk et al., 2015]] ; [[#Petrasek%20MacDonald--2015|Petrasek MacDonald et al., 2015]] ; [[#Kowalczewski--2018|Kowalczewski and Klein, 2018]] ).

Climate change will increase mental health risks in the Arctic in the future ( ''medium confidence'' ). Future risks include exposures to severe weather events and changing precipitation patterns, sea ice loss, wildfires and changing place attachment, as well as disruptions to underlying determinants of mental health and social support networks ( [[#Cunsolo%20Willox--2014|Cunsolo Willox et al., 2014]] ; [[#Cunsolo--2018|Cunsolo and Ellis, 2018]] ; [[#Markon--2018|Markon et al., 2018]] ; [[#Council%20of%20Canadian%20Academies--2019|Council of Canadian Academies, 2019]] ; [[#ITK--2019|ITK, 2019]] ; [[#Middleton--2020a|Middleton et al., 2020a]] ; [[#Middleton--2020b|Middleton et al., 2020b]] ).

There is ''limited evidence'' assessing adaptation options that effectively reduce climate-related mental health risks, but developing or enhancing access to mental health resources and infrastructure is critical, such as land-based healing programmes, enhanced access to culturally appropriate mental health resources, and climate-specific counselling services to support individual and community psychosocial resilience, particularly among Arctic Indigenous Peoples ( [[#Cunsolo--2018|Cunsolo and Ellis, 2018]] ; [[#Middleton--2020a|Middleton et al., 2020a]] ). Incorporating a climate-sensitive mental health lens into mitigation and adaptation planning holds potential for increasing mental health and resilience in the Arctic, as well as supporting other social, economic and cultural co-benefits.

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