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

===== 3.2.1.1.5 Landfast ice =====

Immobile sea ice anchored to land or ice shelves is referred to as ‘landfast’. The few long term surface (auger hole) records of Arctic landfast sea ice thickness all exhibit thinning trends in springtime maximum sea ice thickness since the mid-1960s ( ''high confidence'' ): declines of 11 cm per decade in the Barents Sea (Gerland et al., 2008 <sup>[[#fn:r148|148]]</sup> ), 3.3 cm per decade along the Siberian Coast (Polyakov et al., 2010 <sup>[[#fn:r149|149]]</sup> ), and 3.5 cm per decade in the Canadian Arctic Archipelago (Howell et al., 2016 <sup>[[#fn:r150|150]]</sup> ). Over a shorter 1976–2007 period, winter season landfast sea ice extent from measurements across the Arctic significantly decreased at a rate of 7% per decade, with the largest decreases in the regions of Svalbard (24% per decade) and the northern coast of the Canadian Arctic Archipelago (20% per decade) (Yu et al., 2013 <sup>[[#fn:r151|151]]</sup> ). Svalbard and the Chukchi Sea regions are experiencing the largest declines in landfast sea ice duration (~1 week per decade) since the 1970s (Yu et al., 2013 <sup>[[#fn:r152|152]]</sup> ; Mahoney et al., 2014 <sup>[[#fn:r153|153]]</sup> ). While most Arctic landfast sea ice melts completely each summer, perennial landfast ice (also termed an ‘ice-plug’) occurs in Nansen Sound and the Sverdrup Channel in the Canadian Arctic Archipelago. These ice-plugs were in place continuously from the start of observations in the early 1960s, until they disappeared during the anomalously warm summer of 1998, and they have rarely re-formed since 2005 (Pope et al., 2017 <sup>[[#fn:r154|154]]</sup> ). The loss of this perennial sea ice is associated with reduced landfast ice duration in the northern Canadian Arctic Archipelago (Galley et al., 2012 <sup>[[#fn:r155|155]]</sup> ; Yu et al., 2013 <sup>[[#fn:r156|156]]</sup> ) and increased inflow of multi-year ice from the Arctic Ocean into the northern Canadian Arctic Archipelago (Howell et al., 2013 <sup>[[#fn:r157|157]]</sup> ).

Arctic landfast ice is important to northern residents as a platform for travel, hunting, and access to offshore regions (Sections 3.4.3.3, 3.5.2.2). Reports of thinning, less stable, and less predictable landfast ice have been documented by residents of coastal communities in Alaska (Eisner et al., 2013 <sup>[[#fn:r158|158]]</sup> ; Fall et al., 2013 <sup>[[#fn:r159|159]]</sup> ; Huntington et al., 2017 <sup>[[#fn:r160|160]]</sup> ), the Canadian Arctic (Laidler et al., 2010 <sup>[[#fn:r161|161]]</sup> ), and Chukotka (Inuit Circumpolar Council, 2014). The impact of changing prevailing wind forcing on local ice conditions has been specifically noted (Rosales and Chapman, 2015 <sup>[[#fn:r163|163]]</sup> ) including impacts on the landfast ice edge and polynyas (Box 3.3) (Gearheard et al., 2013 <sup>[[#fn:r164|164]]</sup> ). Long-term records of Antarctic landfast ice are limited in space and time (Stammerjohn and Maksym, 2016 <sup>[[#fn:r165|165]]</sup> ), with a high degree of regional variability in trends (Fraser et al., 2011 <sup>[[#fn:r166|166]]</sup> ) ( ''low confidence'' ).

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