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

=== 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).

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'''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]] ).

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[[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.

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