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

===== 3.2.1.1.4 Motion =====

Winds associated with the climatological Arctic sea level pressure pattern drive the Beaufort Gyre (Dewey et al., 2018 <sup>[[#fn:r133|133]]</sup> ; Meneghello et al., 2018 <sup>[[#fn:r134|134]]</sup> ) and the Transpolar Drift Stream (Vihma et al., 2012 <sup>[[#fn:r135|135]]</sup> ), which retains sea ice within the central Arctic Basin, and exports sea ice out of the Fram Strait, respectively. There is ''high confidence'' that sea ice drift speeds have increased since 1979, both within the Arctic Basin and through Fram Strait (Rampal et al., 2009 <sup>[[#fn:r136|136]]</sup> ; Krumpen et al., 2019 <sup>[[#fn:r137|137]]</sup> ), attributed to thinner ice (Spreen et al., 2011 <sup>[[#fn:r138|138]]</sup> ) and changes in wind forcing (Olason and Notz, 2014 <sup>[[#fn:r139|139]]</sup> ). Fram Strait sea ice area export estimates range between 600,000 to 1 million km 2 of ice annually, which represents approximately 10% of the ice within the Arctic Basin ( ''medium confidence'' ) (Kwok et al., 2013 <sup>[[#fn:r140|140]]</sup> ; Krumpen et al., 2016 <sup>[[#fn:r141|141]]</sup> ; Smedsrud et al., 2017 <sup>[[#fn:r142|142]]</sup> ; Zamani et al., 2019 <sup>[[#fn:r143|143]]</sup> ). Sea ice volume flux estimates through Fram Strait are now available from satellite altimeter datasets (Ricker et al., 2018 <sup>[[#fn:r144|144]]</sup> ), but they cover too short a time period for robust trend analysis. Observations of extreme Arctic sea ice deformation is attributed to the combination of decreased ice thickness and increased ice motion (Itkin et al., 2017 <sup>[[#fn:r145|145]]</sup> ).

Satellite estimates of sea ice drift velocity show significant trends in Antarctic ice drift (Holland and Kwok, 2012 <sup>[[#fn:r146|146]]</sup> ). Increased northward drift in the Ross Sea and decreased northward drift in the Bellingshausen and Weddell seas agree with the respective ice extent gains and losses in these regions, but there is only ''medium confidence'' in these trends due to a small number of ice drift data products derived from temporally inconsistent satellite records (Haumann et al., 2016 <sup>[[#fn:r147|147]]</sup> ).

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