Editing IPCC:AR6/WGI/Chapter-12 (section)

==== 12.3.4.2 Permafrost ====

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Changes in permafrost temperature, extent and active layer thickness are metrics that track how permafrost thaw below, for example, roads, airstrips, rails and building foundations in high-latitude and mountain regions may destabilize settlements and critical infrastructure ( [[#Pendakur--2016|Pendakur, 2016]] ; [[#Derksen--2018|Derksen et al., 2018]] ; [[#Duvillard--2019|Duvillard et al., 2019]] ; [[#Olsson--2019|Olsson et al., 2019]] ; [[#Streletskiy--2019|Streletskiy et al., 2019]] ). Warmer conditions can also affect ecosystems, built infrastructure and water resources through thawing of especially ice-rich permafrost (≥20% ice content) and by thawing of ice wedges ( [[#Shiklomanov--2017|Shiklomanov et al., 2017]] ; [[#Hjort--2018|Hjort et al., 2018]] ), creation of thermokarst ponds and increased subsurface drainage for polar and high-mountain wetlands ( [[#Walvoord--2016|Walvoord and Kurylyk, 2016]] ; [[#Farquharson--2019|Farquharson et al., 2019]] ) and the release of water pollutants such as mercury ( [[#Burkett--2011|Burkett, 2011]] ; [[#Schaeffer--2012|Schaeffer et al., 2012]] ; [[#Schuster--2018|Schuster et al., 2018]] ).

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