Editing IPCC:AR6/SROCC/Chapter-3 (section)

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

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In polar regions climate-induced changes in terrestrial, ocean and sea ice environments, together with human introduction of non-native species, have expanded the range of some temperate species and contracted the range of some polar fish and ice-associated species (Section 3.2.3.2; Duffy et al., 2017 <sup>[[#fn:r1752|1752]]</sup> ) ( ''high confidence'' for detection '', medium confidence'' for attribution). In some cases, spatial shifts in distribution have also been influenced by fluctuations in population abundance linked to climate-induced impacts on reproductive success (Section 3.2.3). These changes have the potential to alter biodiversity in polar marine and terrestrial ecosystems (Frenot et al., 2005 <sup>[[#fn:r1753|1753]]</sup> ; Frederiksen, 2017 <sup>[[#fn:r1754|1754]]</sup> ; McCarthy et al., 2019 <sup>[[#fn:r1755|1755]]</sup> ) ( ''medium confidence'' ).

Ongoing climate change induced reductions in suitable habitat for Arctic sea ice affiliated endemic marine mammals is an escalating threat (Section 3.2.3.1) ( ''high confidence'' ). This is further complicated by the northward expansion of the summer ranges of a variety of temperate whale species, documented recently in both the Pacific and Atlantic sides of the Arctic (Brower et al., 2017 <sup>[[#fn:r1756|1756]]</sup> ; Storrie et al., 2018 <sup>[[#fn:r1757|1757]]</sup> ) and increasing pressure from anthropogenic activities. Also, over the recent decade a northward shift in benthic species, with subsequent changes in community composition has been detected in both the northern Bering Sea (Grebmeier, 2012 <sup>[[#fn:r1758|1758]]</sup> ), off Western Greenland (Renaud et al., 2015 <sup>[[#fn:r1759|1759]]</sup> ) and the Barents Sea (Kortsch et al., 2012 <sup>[[#fn:r1760|1760]]</sup> ) ( ''medium confidence'' ). At the same time as these northward expansions or shifts, a number of populations of species as different as polar bear and Arctic char show range contraction or population declines (Winfield et al., 2010 <sup>[[#fn:r1761|1761]]</sup> ; Bromaghin et al., 2015 <sup>[[#fn:r1762|1762]]</sup> ; Laidre et al., 2018 <sup>[[#fn:r1763|1763]]</sup> ).

In the Arctic a number of fish species have changed their spatial distribution substantially over the recent decades ( ''high confidence'' ). The most pronounced recent range expansion into the Arctic may be that of the summer feeding distribution of the temperate Atlantic mackerel ( ''Scomber scombrus'' ) in the Nordic Seas. From 1997 to 2016 the total area occupied by this large stock expanded from 0.4 to 2.5 million km 2 and the centre-of-gravity of distribution shifted westward by 1650 km and northward by 400 km (Olafsdottir et al., 2019), far into Icelandic and Greenland waters and even up to Svalbard (Berge et al., 2015 <sup>[[#fn:r1764|1764]]</sup> ; Jansen et al., 2016 <sup>[[#fn:r1765|1765]]</sup> ; Nøttestad et al., 2016 <sup>[[#fn:r1766|1766]]</sup> ). This range expansion was linked both to a pronounced increase in stock size and warming of the ocean (Berge et al., 2015 <sup>[[#fn:r1767|1767]]</sup> ; Olafsdottir et al., 2019 <sup>[[#fn:r1768|1768]]</sup> ) ( ''high confidence'' ). Under RCP4.5 and RCP8.5 further range expansions of mackerel are projected in Greenland waters (Jansen et al., 2016 <sup>[[#fn:r1769|1769]]</sup> ) ( ''medium confidence'' ). However, further northwards expansion of planktivorous species may generally be restricted by them not being adapted to lack of primary production during winter (Sundby et al., 2016 <sup>[[#fn:r1770|1770]]</sup> ). Range shifts have also been observed in the Bering Sea since 1993, with warm bottom temperatures being associated with range contractions of Arctic species, and range expansions of sub-arctic species, with responses dependent on species specific vulnerably (Alabia et al., 2018 <sup>[[#fn:r1771|1771]]</sup> ; Stevenson and Lauth, 2018 <sup>[[#fn:r1772|1772]]</sup> ).

In the Barents Sea, major expansions in distribution over the recent years to decades have been well documented for both individual species and whole biological communities ( ''high confidence'' ). New information strengthens findings reported in WGII AR5 of ecologically and commercially important fish stocks having extended their habitats markedly to the north and east, concomitant to increased sea temperature and retreating sea ice. This includes capelin (Ingvaldsen and Gjøsæter, 2013 <sup>[[#fn:r1773|1773]]</sup> ), Atlantic cod (Kjesbu et al., 2014 <sup>[[#fn:r1774|1774]]</sup> ) and haddock (Landa et al., 2014 <sup>[[#fn:r1775|1775]]</sup> ). Of even greater importance is novel evidence of distinct distributional changes at the community level (Fossheim et al., 2015 <sup>[[#fn:r1776|1776]]</sup> ; Kortsch et al., 2015 <sup>[[#fn:r1777|1777]]</sup> ; Frainer et al., 2017 <sup>[[#fn:r1778|1778]]</sup> ) (Box 3.4 Figure 1). Until recently, the northern Barents Sea was dominated by small-sized, slow-growing fish species with specialised diets, mostly living in close association with the sea floor. Simultaneous with rising sea temperatures and retreating sea ice, these Arctic fishes are being replaced by boreal, fast-growing, large-bodied generalist fish moving in from the south. These large, migratory predators take advantage of increased production while the Arctic fish species suffer from higher competition and predation and are retracting northwards and eastwards. Consequently, climate change is inducing structural change over large spatial scales, leading to a borealisation (‘Atlantification’) of the European Arctic biological communities (Fossheim et al., 2015 <sup>[[#fn:r1779|1779]]</sup> ; Kortsch et al., 2015 <sup>[[#fn:r1780|1780]]</sup> ; Frainer et al., 2017 <sup>[[#fn:r1781|1781]]</sup> ) ( ''medium confidence'' ).

There is evidence based on population genetics that the ecosystem off Northeast Greenland could also become populated by a larger proportion of boreal species with ocean warming. Andrews et al. (2019) <sup>[[#fn:r1782|1782]]</sup> show that Atlantic cod, beaked redfish ( ''Sebastes mentella'' ), and deep-sea shrimp ( ''Pandalus borealis'' ) recently found on the Northeast Greenland shelf originate from the quite distant Barents Sea, and suggested that pelagic offspring were dispersed via advection across the Fram Strait.

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'''Box 3.4, Figure 1'''

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'''Spatial distribution of fish communities identified at bottom trawl stations in the Barents Sea (north of northern Norway and Russia, position indicated by red box in small globe) in (a) 2004 and (b) 2012. Atlantic (red), Arctic (blue) and Central communities (yellow). Circles: shallow sub-communities, triangles: deep sub-communities. Modified from Fossheim et al. (2015).'''
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[[File:d730cedc393bc8b382a6b48540e95cbd IPCC-SROCC-CH_3_Box3_4.jpg]]

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

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Physical barriers to range expansions into the high Arctic interior shelf systems and the outflow systems of Eurasia and the Canadian Archipelago will continue to govern future expansions of fish populations ( ''medium confidence'' ). The limited available information on marine fish from other Arctic shelf regions reveals a latitudinal cline in the abundance of commercially harvestable fish species. For instance, there is evidence of latitudinal partitioning between the four dominant mid-water species (Polar cod, saffron cod ( ''Eleginus gracilis'' ), capelin, and Pacific herring ( ''Clupea pallasii'' )) in the Chuckchi and Northern Bering Sea, with Polar cod being most abundant to the north (De Robertis et al., 2017). These latitudinal gradients suggest that future range expansions of fish populations will continue to be governed by a combination of physical factors affecting overwintering success and the availability, quality and quantity of prey ( ''medium confidence'' ).

In Antarctic marine systems, there is evidence of recent climate-related range shifts in the southwest Atlantic and West Antarctic Peninsula for penguin species ( ''Pygoscelis papua'' and ''P. antarctica'' ) and for Antarctic krill ( ''Euphausia superba'' ), but mesozooplankton communities do not appear to have changed or shifted in response to ocean warming (Section 3.2.3.2). Recent evidence suggests that the ACC and its associated fronts and thermal gradients may be more permeable to biological dispersal than previously thought, with storm-forced surface waves and ocean eddies enhancing oceanographic connectivity for drift particles in surface layers of the Southern Ocean (Fraser et al., 2017 <sup>[[#fn:r1783|1783]]</sup> ; Fraser et al., 2018 <sup>[[#fn:r1784|1784]]</sup> ) ( ''low confidence'' ), but it is unclear whether this will be an increasingly important pathway under climate change. Greater ship activity in the Southern Ocean may also present a risk for increasing introduction of non-native marine species, with the potential for these species to become invasive with changing environmental conditions (McCarthy et al., 2019 <sup>[[#fn:r1785|1785]]</sup> ). Current evidence of invasions by shell-crushing crabs on the Antarctic continental slope and shelf remains equivocal (Griffiths et al., 2013 <sup>[[#fn:r1786|1786]]</sup> ; Aronson et al., 2015 <sup>[[#fn:r1787|1787]]</sup> ; Smith et al., 2017d <sup>[[#fn:r1788|1788]]</sup> ).

On Arctic land, northward range expansions have been recorded in species from all major taxon groups based both on scientific studies and local observations ( ''high confidence'' ) (CAFF, 2013a <sup>[[#fn:r1789|1789]]</sup> ; AMAP, 2017a <sup>[[#fn:r1790|1790]]</sup> ; AMAP, 2017b <sup>[[#fn:r1791|1791]]</sup> ; AMAP, 2018 <sup>[[#fn:r1792|1792]]</sup> ). The most recent examples of terrestrial vertebrates expanding northwards include a whole range of mammals in Yakutia, Russia (Safronov, 2016 <sup>[[#fn:r1793|1793]]</sup> ), moose ( ''Alces alces'' ) into the Arctic region of both northern continents (Tape et al., 2016 <sup>[[#fn:r1795|1795]]</sup> ) and North American beaver ( ''Castor canadensis'' ) in Alaska (Tape et al., 2018 <sup>[[#fn:r1794|1794]]</sup> ). In parallel with these expansions, pathogens and pests are also spreading north (CAFF, 2013a <sup>[[#fn:r1796|1796]]</sup> ; Taylor et al., 2015 <sup>[[#fn:r1797|1797]]</sup> ; Forde et al., 2016b <sup>[[#fn:r1798|1798]]</sup> ; Burke et al., 2017b <sup>[[#fn:r1799|1799]]</sup> ; Kafle et al., 2018 <sup>[[#fn:r1800|1800]]</sup> ). A widespread change is tundra greening, which in some cases is linked to shifting plant dominance within Arctic plant communities, in particular an increase in woody shrub biomass as conditions become more favorable for them (Myers-Smith et al., 2015 <sup>[[#fn:r1801|1801]]</sup> ; Bhatt et al., 2017 <sup>[[#fn:r1802|1802]]</sup> ).

Expansion of subarctic terrestrial species and biological communities into the Arctic and displacing native species is considered a major threat, since unique Arctic species may be less competitive than encroaching subarctic species favoured by changing climatic conditions (CAFF, 2013a <sup>[[#fn:r1803|1803]]</sup> ). Similar displacements may take place within zones of the Arctic when low- and mid-Arctic species expand northward. Here, the most vulnerable species and communities may be in the species-poor, but unique, northernmost sub-zone of the Arctic because species cannot migrate northward as southern species encroach (CAVM Team, 2003 <sup>[[#fn:r1804|1804]]</sup> ; Walker et al., 2016 <sup>[[#fn:r1805|1805]]</sup> ; AMAP, 2018 <sup>[[#fn:r1806|1806]]</sup> ). This ‘Arctic squeeze’ is a combined effect of the fact that the area of the globe increasingly shrinks when moving poleward and that there is nowhere further north on land to go for terrestrial biota at the northern coast. The expected overall result of these shifts and limits will be a loss of biodiversity (CAFF, 2013a <sup>[[#fn:r1807|1807]]</sup> ; CAFF, 2013b <sup>[[#fn:r1808|1808]]</sup> ; AMAP, 2018 <sup>[[#fn:r1809|1809]]</sup> ) ( ''medium confidence'' ). At the southern limit of the Arctic, thermal hotspots may support high biological productivity, but not necessarily high biodiversity (Walker et al., 2015 <sup>[[#fn:r1810|1810]]</sup> ) and may even act as advanced bridgeheads for expansion of subarctic species into the true Arctic ( ''medium confidence'' ). At the other end of the Arctic zonal range, a temperature increase of only 1°C –2°C in the northernmost subzone may allow the establishment of woody dwarf shrubs, sedges and other species into bare soil areas that may radically change its appearance and ecological functions (Walker et al., 2015 <sup>[[#fn:r1811|1811]]</sup> ; Myers ‐ Smith et al., 2019 <sup>[[#fn:r1812|1812]]</sup> ) ( ''medium confidence'' ).

Range expansions also include the threat from alien species brought in by humans to become invasive and outcompete native species. Relatively few invasive alien species are presently well established in the Arctic, but many are thriving in the subarctic and may expand as a result of climate change (CAFF, 2013a <sup>[[#fn:r1813|1813]]</sup> ; CAFF, 2013b[). Examples of this include: American mink ( ''Neovison vison'' ) and Nootka lupin ( ''Lupinus nootkatensis'' ) in Arctic western Eurasia, Greenland and Iceland that are already causing severe problems to native fauna and flora (CAFF and PAME, 2017).

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

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<span id="impacts-on-social-ecological-systems-1"></span>
==== 3.4.3.3 Impacts on Social-Ecological Systems ====

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The Arctic is home to over four million people, with large regional variation in population distribution and demographics (Heleniak, 2014 <sup>[[#fn:r1824|1824]]</sup> ). ‘Connection with nature’ is a defining feature of Arctic identity for indigenous communities (Schweitzer et al., 2014) because the lands, waters and ice that surround communities evoke a sense of home, freedom and belonging, and are crucial for culture, life and survival (Cunsolo Willox et al., 2012 <sup>[[#fn:r1825|1825]]</sup> ; Durkalec et al., 2015 <sup>[[#fn:r1826|1826]]</sup> ). Climate-driven environmental changes are affecting local ecosystems and influencing travel, hunting, fishing and gathering practises. This has implications for people’s livelihoods, cultural practices, economies and self-determination.

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<span id="food-and-water-security"></span>
===== 3.4.3.3.1 Food and water security =====

Impacts of climate change on food and water security in the Arctic can be severe in regions where infrastructure (including ice roads), travel and subsistence practices are reliant on elements of the cryosphere such as snow cover, permafrost and freshwater or sea ice (Cochran et al., 2013 <sup>[[#fn:r1828|1828]]</sup> ; Inuit Circumpolar Council-Alaska (ICC-AK), 2015).

There is ''high confidence'' in indicators that food insecurity risks are on the rise for Indigenous Arctic peoples. Food is strongly tied to culture, identity, values and ways of life (Donaldson et al., 2010 <sup>[[#fn:r1829|1829]]</sup> ; Cunsolo Willox et al., 2015 <sup>[[#fn:r1830|1830]]</sup> ; Inuit Circumpolar Council-Alaska (ICC-AK), 2015); thus, impacts to food security go beyond access to food and physical health. Food systems in northern communities are intertwined with northern ecosystems because of subsistence hunting, fishing and gathering activities. Environmental changes to animal habitat, population sizes and movement mean that culturally important food species may no longer be found within accessible ranges or familiar areas (Parlee and Furgal, 2012 <sup>[[#fn:r1831|1831]]</sup> ; Rautio et al., 2014 <sup>[[#fn:r1832|1832]]</sup> ; Inuit Circumpolar Council-Alaska (ICC-AK), 2015; Lavrillier et al., 2016 <sup>[[#fn:r1833|1833]]</sup> ) (Section 3.4.3.2.2). This impacts negatively the accessibility of culturally important local food sources (Lavrillier, 2013; Rosol et al., 2016 <sup>[[#fn:r1834|1834]]</sup> ) that make important contributions to a nutritious diet (Donaldson et al., 2010 <sup>[[#fn:r1835|1835]]</sup> ; Hansen et al., 2013 <sup>[[#fn:r1836|1836]]</sup> ; Dudley et al., 2015 <sup>[[#fn:r1837|1837]]</sup> ). Longer open water seasons and poorer ice conditions on lakes impact fishing options (Laidler, 2012 <sup>[[#fn:r1838|1838]]</sup> ) and waterfowl hunting (Goldhar et al., 2014 <sup>[[#fn:r1839|1839]]</sup> ). Permafrost warming and increases in active layer thickness (Section 3.4.1.3) reduce the reliability of permafrost for natural refrigeration. In some cases these changes have reduced access to, and consumption of, locally resourced food and can result in increased incidence of illness (Laidler, 2012 <sup>[[#fn:r1840|1840]]</sup> ; Cochran et al., 2013 <sup>[[#fn:r1841|1841]]</sup> ; Cozzetto et al., 2013 <sup>[[#fn:r1842|1842]]</sup> ; Rautio et al., 2014 <sup>[[#fn:r1843|1843]]</sup> ; Beaumier et al., 2015 <sup>[[#fn:r1844|1844]]</sup> ). These consequences of climate change are intertwined with processes of globalisation, whereby complex social, economic and cultural factors are contributing to a dietary transformation from locally resourced foods to imported market foods across the Arctic (Harder and Wenzel, 2012 <sup>[[#fn:r1845|1845]]</sup> ; Parlee and Furgal, 2012 <sup>[[#fn:r1846|1846]]</sup> ; Nymand and Fondahl, 2014 <sup>[[#fn:r1847|1847]]</sup> ; Beaumier et al., 2015 <sup>[[#fn:r1848|1848]]</sup> ). Limiting exposures to zoonotic, foodborne and waterborne pathogens (Section 3.4.3.2.2) depends on accurate and comprehensive data on species diversity, biology and distribution and pathways for invasion (Hoberg and Brooks, 2015 <sup>[[#fn:r1849|1849]]</sup> ; Kafle et al., 2018 <sup>[[#fn:r1850|1850]]</sup> ).

There is ''high confidence'' that changes to travel conditions impact food security through access to hunting grounds. Shorter snow cover duration (Section 3.4.1.1), and changes to snow conditions (such as density) make travel more difficult and dangerous (Laidler, 2012 <sup>[[#fn:r1851|1851]]</sup> ; Ford et al., 2019 <sup>[[#fn:r1852|1852]]</sup> ). Changes in dominant wind direction and speed reduce the reliability of traditional navigational indicators such as snow drifts, increasing safety concerns (Ford and Pearce, 2012 <sup>[[#fn:r1853|1853]]</sup> ; Laidler, 2012 <sup>[[#fn:r1854|1854]]</sup> ; Ford et al., 2013 <sup>[[#fn:r1855|1855]]</sup> ; Clark et al., 2016b <sup>[[#fn:r1856|1856]]</sup> ). Permafrost warming, increased active layer thickness and landscape instability (Section 3.4.1.3), fire disturbance and changes to water levels (Section 3.4.1.2) impact overland navigability in summer (Goldhar et al., 2014 <sup>[[#fn:r1857|1857]]</sup> ; Brinkman et al., 2016 <sup>[[#fn:r1858|1858]]</sup> ; Dodd et al., 2018 <sup>[[#fn:r1859|1859]]</sup> ).

There is ''high confidence'' that both risks and opportunities arise for coastal communities with changing sea ice and open water conditions. Of particular concern for coastal communities is landfast sea ice (Section 3.3.1.1.5), which creates an extension of the land in winter that facilitates travel (Inuit Circumpolar Council Canada, 2014 <sup>[[#fn:r1860|1860]]</sup> ). The floe edge position, timing and dynamics of freeze-up and break-up, sea ice stability through the winter, and length of the summer open water season are important indicators of changing ice conditions and safe travel (Gearheard et al., 2013 <sup>[[#fn:r1861|1861]]</sup> ; Eicken et al., 2014 <sup>[[#fn:r1862|1862]]</sup> ; Baztan et al., 2017 <sup>[[#fn:r1863|1863]]</sup> ). Warming water temperature, altered salinity profiles, snow properties, changing currents and winds all have consequences for the use of sea ice as a travel or hunting platform (Hansen et al., 2013 <sup>[[#fn:r1864|1864]]</sup> ; Eicken et al., 2014 <sup>[[#fn:r1865|1865]]</sup> ; Clark et al., 2016a <sup>[[#fn:r1866|1866]]</sup> ). More leads (areas of open water), especially in the spring, can mean more hunting opportunities such as whaling off the coast of Alaska (Hansen et al., 2013 <sup>[[#fn:r1867|1867]]</sup> ; Eicken et al., 2014 <sup>[[#fn:r1868|1868]]</sup> ). In Nunavut, a floe edge closer to shore improves access to marine mammals such as seals or narwhal (Ford et al., 2013 <sup>[[#fn:r1869|1869]]</sup> ). However, these conditions also hamper access to coastal or inland hunting grounds (Hansen et al., 2013 <sup>[[#fn:r1870|1870]]</sup> ; Durkalec et al., 2015 <sup>[[#fn:r1871|1871]]</sup> ), have increased potential for break-off events at the floe edge (Ford et al., 2013 <sup>[[#fn:r1872|1872]]</sup> ), or can result in decreased presence (or total absence) of ice-associated marine mammals with an absence of summer sea ice (Eicken et al., 2014 <sup>[[#fn:r1873|1873]]</sup> ).

Many northern communities rely on ponds, streams and lakes for drinking water (Cochran et al., 2013 <sup>[[#fn:r1874|1874]]</sup> ; Goldhar et al., 2013 <sup>[[#fn:r1875|1875]]</sup> ; Nymand and Fondahl, 2014 <sup>[[#fn:r1876|1876]]</sup> ; Daley et al., 2015 <sup>[[#fn:r1877|1877]]</sup> ; Dudley et al., 2015 <sup>[[#fn:r1878|1878]]</sup> ; Masina et al., 2019 <sup>[[#fn:r1879|1879]]</sup> ), so there is ''high confidence'' that projected changes in hydrology will impact water supply (Section 3.4.2.2). Surface water is vulnerable to thermokarst disturbance and drainage, as well as bacterial contamination, the risks of which are increased by warming ground and water temperatures (Cozzetto et al., 2013 <sup>[[#fn:r1880|1880]]</sup> ; Goldhar et al., 2013 <sup>[[#fn:r1881|1881]]</sup> ; Dudley et al., 2015 <sup>[[#fn:r1882|1882]]</sup> ; Masina et al., 2019 <sup>[[#fn:r1883|1883]]</sup> ). Icebergs or old multi-year ice are important sources of drinking water for some coastal communities, so reduced accessibility to stable sea ice conditions affects local water security. Small remote communities have limited capacity to respond quickly to water supply threats, which amplifies vulnerabilities to water security (Daley et al., 2015 <sup>[[#fn:r1884|1884]]</sup> ).

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<span id="communities"></span>
===== 3.4.3.3.2 Communities =====

''Culture and knowledge''

Spending time on the land is culturally important for indigenous communities (Eicken et al., 2014 <sup>[[#fn:r1885|1885]]</sup> ; Durkalec et al., 2015 <sup>[[#fn:r1886|1886]]</sup> ). There is ''high confidence'' that daily life is influenced by changes to ice freeze-up and break-up (rivers/lakes/sea ice), snow onset/melt, vegetation phenology, and related wildlife/fish/bird behaviour (Inuit Circumpolar Council-Alaska (ICC-AK), 2015). Inter-generational knowledge transmission of associated values and skills is also influenced by climate change because younger generations do not have the same level of experience or confidence with traditional indicators (Ford, 2012 <sup>[[#fn:r1887|1887]]</sup> ; Parlee and Furgal, 2012 <sup>[[#fn:r1888|1888]]</sup> ; Eicken et al., 2014 <sup>[[#fn:r1889|1889]]</sup> ; Pearce et al., 2015 <sup>[[#fn:r1890|1890]]</sup> ). Climate-driven changes undermine confidence in indigenous knowledge holders in regards to traditional indicators used for safe travel and navigation (Parlee and Furgal, 2012 <sup>[[#fn:r1891|1891]]</sup> ; Golovnev, 2017 <sup>[[#fn:r1892|1892]]</sup> ; Ford et al., 2019 <sup>[[#fn:r1893|1893]]</sup> ).

''Economics''

The Arctic mixed economy is characterised by a combination of subsistence activities, and employment and cash income. There is ''low confidence'' about the extent and nature of impact of climate change on local subsistence activities and economic opportunities across the Arctic (e.g., hunting, fishing, resource extraction, tourism and transportation; see Section 3.2.4) because of high variability between communities (Harder and Wenzel, 2012 <sup>[[#fn:r1894|1894]]</sup> ; Cochran et al., 2013 <sup>[[#fn:r1895|1895]]</sup> ; Clark et al., 2016b <sup>[[#fn:r1896|1896]]</sup> ; Fall, 2016 <sup>[[#fn:r1897|1897]]</sup> ; Ford et al., 2016 <sup>[[#fn:r1898|1898]]</sup> ; Lavrillier et al., 2016 <sup>[[#fn:r1899|1899]]</sup> ). Longer ice-free travel windows in Arctic seas could lower the costs of access and development of northern resources (delivering supplies and shipping resources to markets) and thus, may contribute to increased opportunities for marine shipping, commercial fisheries, tourism and resource development (Sections 3.2.4.2, 3.2.4.3) (Ford et al., 2012 <sup>[[#fn:r1900|1900]]</sup> ; Huskey et al., 2014 <sup>[[#fn:r1901|1901]]</sup> ; Overland et al., 2017 <sup>[[#fn:r1902|1902]]</sup> ). This has important implications for economic development, particularly in relation to local employment opportunities but also raises concerns of detrimental impacts on animals, habitat and subsistence activities (Cochran et al., 2013 <sup>[[#fn:r1903|1903]]</sup> ; Inuit Circumpolar Council-Alaska (ICC-AK), 2015).

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<span id="health-and-wellbeing"></span>
===== 3.4.3.3.3 Health and wellbeing =====

For many polar residents, especially Indigenous peoples, the physical environment underpins social determinants of well-being, including physical and mental health. Changes to the environment impact most dimensions of health and well-being (Parlee and Furgal, 2012 <sup>[[#fn:r1904|1904]]</sup> ; Ostapchuk et al., 2015 <sup>[[#fn:r1905|1905]]</sup> ). Climate change consequences in polar regions (Sections 3.3.1.1, 3.4.1.2) have impacted key transportation routes (Gearheard et al., 2006 <sup>[[#fn:r1906|1906]]</sup> ; Laidler, 2006 <sup>[[#fn:r1907|1907]]</sup> ; Ford et al., 2013 <sup>[[#fn:r1908|1908]]</sup> ; Clark et al., 2016a <sup>[[#fn:r1909|1909]]</sup> ) and pose increased risk of injury and death during travel (Durkalec et al., 2014 <sup>[[#fn:r1910|1910]]</sup> ; Durkalec et al., 2015 <sup>[[#fn:r1911|1911]]</sup> ; Clark et al., 2016b <sup>[[#fn:r1912|1912]]</sup> ; Driscoll et al., 2016 <sup>[[#fn:r1913|1913]]</sup> ).

Foodborne disease is an emerging concern in the Arctic because warmer waters, loss of sea ice (Section 3.3.1.1) and resultant changes in contaminant pathways can lead to bioaccumulation and biomagnification of contaminants in key food species. While many hypothesised foodborne diseases are not well studied (Parkinson and Berner, 2009 <sup>[[#fn:r1914|1914]]</sup> ), foodborne gastroenteritis is associated with shellfish harvested from warming waters (McLaughlin et al., 2005 <sup>[[#fn:r1915|1915]]</sup> ; Young et al., 2015 <sup>[[#fn:r1916|1916]]</sup> ). Mercury presently stored in permafrost (Schuster et al., 2018 <sup>[[#fn:r1917|1917]]</sup> ) has potential to accumulate in aquatic ecosystems.

Climate change increases the risk of waterborne disease in the Arctic via warming water temperatures and changes to surface hydrology (Section 3.4.1.2) (Parkinson and Berner, 2009 <sup>[[#fn:r1918|1918]]</sup> ; Brubaker et al., 2011 <sup>[[#fn:r1910|1910]]</sup> ; Dudley et al., 2015 <sup>[[#fn:r1920|1920]]</sup> ). After periods of rapid snowmelt, bacteria can increase in untreated drinking water, with associated increases in acute gastrointestinal illness (Harper et al., 2011 <sup>[[#fn:r1921|1921]]</sup> ). Consumption of untreated drinking water may increase duration and frequency of exposure to local environmental contaminants (Section 3.4.3.2.3) or potential waterborne diseases (Goldhar et al., 2014 <sup>[[#fn:r1922|1922]]</sup> ; Daley et al., 2015 <sup>[[#fn:r1923|1923]]</sup> ). The potential for infectious gastrointestinal disease is not well understood, and there are concerns in relation to the safety of storage containers of raw water in addition to the quality of the source water itself (Goldhar et al., 2014 <sup>[[#fn:r1924|1924]]</sup> ; Wright et al., 2018 <sup>[[#fn:r1925|1925]]</sup> ; Masina et al., 2019 <sup>[[#fn:r1926|1926]]</sup> ).

Climate change has negatively affected place attachment via hunting, fishing, trapping and traveling disruptions, which have important mental health impacts (Cunsolo Willox et al., 2012 <sup>[[#fn:r1927|1927]]</sup> ; Durkalec et al., 2015 <sup>[[#fn:r1928|1928]]</sup> ; Cunsolo and Ellis, 2018 <sup>[[#fn:r1929|1929]]</sup> ). The pathways through which climate change impacts mental wellness in the Arctic varies by gender (Bunce and Ford, 2015 <sup>[[#fn:r1930|1930]]</sup> ; Ostapchuk et al., 2015 <sup>[[#fn:r1931|1931]]</sup> ; Bunce et al., 2016 <sup>[[#fn:r1932|1932]]</sup> ) and age (Petrasek-MacDonald et al., 2013 <sup>[[#fn:r1933|1933]]</sup> ; Ostapchuk et al., 2015 <sup>[[#fn:r1934|1934]]</sup> ). Emotional impacts of climate-related changes in the environment were significantly higher for women compared to men, linked to concern for family members (Ostapchuk et al., 2015 <sup>[[#fn:r1935|1935]]</sup> ). However, men are also vulnerable due to gendered roles in subsistence and cultural activities (Bunce and Ford, 2015 <sup>[[#fn:r1936|1936]]</sup> ). In coastal areas, sea ice means freedom for travel, hunting and fishing, so changes in sea ice affect the experience of and connection with place. In turn, this influences individual and collective mental/emotional health, as well as spiritual and social vitality according to relationships between sea ice use, culture, knowledge and autonomy (Cunsolo Willox et al., 2013a <sup>[[#fn:r1937|1937]]</sup> ; Cunsolo Willox et al., 2013b <sup>[[#fn:r1938|1938]]</sup> ; Gearheard et al., 2013 <sup>[[#fn:r1939|1939]]</sup> ; Durkalec et al., 2015 <sup>[[#fn:r1940|1940]]</sup> ; Inuit Circumpolar Council-Alaska (ICC-AK), 2015).

<div id="section-3-4-3-3-impacts-on-social-ecological-systems-block-5"></div>

<span id="infrastructure"></span>
===== 3.4.3.3.4 Infrastructure =====

Permafrost is undergoing rapid change (Section 3.4.1.2), creating challenges for planners, decision makers and engineers (AMAP, 2017d <sup>[[#fn:r1941|1941]]</sup> ). The observed changes in the ground thermal regime (Romanovsky et al., 2010 <sup>[[#fn:r1942|1942]]</sup> ; Romanovsky et al., 2017 <sup>[[#fn:r1943|1943]]</sup> ; Biskaborn et al., 2019 <sup>[[#fn:r1944|1944]]</sup> ) threaten the structural stability and functional capacities of infrastructure, in particular that which is located on ice rich frozen ground. Extensive summaries of construction damages along with adaptation and mitigation strategies are available (Larsen et al., 2014 <sup>[[#fn:r1945|1945]]</sup> ; Dore et al., 2016 <sup>[[#fn:r1946|1946]]</sup> ; AMAP, 2017d <sup>[[#fn:r1947|1947]]</sup> ; Pendakur, 2017 <sup>[[#fn:r1948|1948]]</sup> ; Shiklomanov et al., 2017a <sup>[[#fn:r1949|1949]]</sup> ; Shiklomanov et al., 2017b <sup>[[#fn:r1950|1950]]</sup> ; Vincent et al., 2017 <sup>[[#fn:r1951|1951]]</sup> ).

Projections of climate and permafrost suggest that a wide range current infrastructure will be impacted by changing conditions ( ''medium confidence'' ). A circumpolar study found that approximately 70% of infrastructure (residential, transportation and industrial facilities), including over 1200 settlements (~40 with population more than 5000) are located in areas where permafrost is projected to thaw by 2050 under RCP4.5 (Hjort et al., 2018 <sup>[[#fn:r1952|1952]]</sup> ). Regions associated with the highest hazard are in the thaw-unstable zone characterised by relatively high ground-ice content and thick deposits of frost susceptible sediments (Shiklomanov et al., 2017b <sup>[[#fn:r1953|1953]]</sup> ). By 2050, these high hazard environments contain one-third of existing pan-Arctic infrastructure. Onshore hydrocarbon extraction and transportation in the Russian Arctic are at risk: 45% of the oil and natural gas production fields in the Russian Arctic are located in the highest hazard zone.

In a regional study of the state of Alaska, cumulative expenses projected for climate-related damage to public infrastructure totalled USD 5.5 billion between 2015 and 2099 under RCP8.5 (Melvin et al., 2017 <sup>[[#fn:r1954|1954]]</sup> ). The top two causes of damage related costs were projected to be road flooding from increased precipitation, and building damage associated with near-surface permafrost thaw. These costs decreased by 24% to USD 4.2 billion for the same time frame under RCP4.5, indicating that reducing greenhouse gas emissions globally could lessen damages (Figure 3.13). In a related study that included these costs and others, as well as positive gains from climate change in terms of a reduction in heating costs attributable to warmer winter, annual net costs were still USD 340–700 million, or 0.6–1.3% of Alaska’s GDP, suggesting that climate change costs will outweigh positive benefits, at least for this region (Berman and Schmidt, 2019 <sup>[[#fn:r1955|1955]]</sup> ).

Winter roads (snow covered ground and frozen lakes) are distinct from the infrastructure considered earlier, but have a strong influence on the reliability and costs of transportation in some remote northern communities and industrial development sites (Parlee and Furgal, 2012 <sup>[[#fn:r1956|1956]]</sup> ; Huskey et al., 2014 <sup>[[#fn:r1957|1957]]</sup> ; Overland et al., 2017 <sup>[[#fn:r1958|1958]]</sup> ). For these communities, changing lake and river levels and the period of safe ice cover all affect the duration of use of overland travel routes and inland waterways, with associated implications for increased travel risks, time, and costs (Laidler, 2012 <sup>[[#fn:r1959|1959]]</sup> ; Ford et al., 2013 <sup>[[#fn:r1960|1960]]</sup> ; Goldhar et al., 2014 <sup>[[#fn:r1961|1961]]</sup> ). There have been recent instances of severely curtailed ice road shipping seasons due to unusually warm conditions in the early winter (Sturm et al., 2017 <sup>[[#fn:r1962|1962]]</sup> ). While the impact of human effort on the maintenance of winter roads is difficult to quantify, a reduction in the operational time window due to winter warming is projected (Mullan et al., 2017 <sup>[[#fn:r1963|1963]]</sup> ).

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