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

===== 3.4.1.1.1 Extent and duration =====

Dramatic reductions in Arctic (land areas north of 60°N) spring snow cover extent have occurred since satellite charting began in 1967 (Estilow et al., 2015). Declines in May and June of –3.5% (± 1.9%) and –13.4% respectively per decade (± 5.4%) between 1967 and 2018 (relative to the 1981–2010 mean) were determined from multiple datasets based on the methodology of (Mudryk et al., 2017 <sup>[[#fn:r1351|1351]]</sup> ) (Figure 3.10) ( ''high confidence'' ). The loss of spring snow extent is reflected in shorter snow cover duration estimated from surface observations (Bulygina et al., 2011 <sup>[[#fn:r1352|1352]]</sup> ; Brown et al., 2017 <sup>[[#fn:r1353|1353]]</sup> ), satellite data (Wang et al., 2013 <sup>[[#fn:r1354|1354]]</sup> ; Estilow et al., 2015 <sup>[[#fn:r1355|1355]]</sup> ; Anttila et al., 2018 <sup>[[#fn:r1356|1356]]</sup> ), and model-based analyses (Liston and Hiemstra, 2011 <sup>[[#fn:r1357|1357]]</sup> ) ( ''high confidence'' ). These trends range between –0.7 and –3.9 days per decade depending on region and time period, but all spring snow cover duration trends from all datasets are negative (Brown et al., 2017 <sup>[[#fn:r1358|1358]]</sup> ). These same multi-source datasets also identify reductions in autumn snow extent and duration (-0.6 to -1.4 days per decade; summarized in Brown et al., 2017) ( ''high confidence'' ). There is ''low confidence'' in positive October and November snow cover extent trends apparent in a single dataset (Hernández-Henríquez et al., 2015 <sup>[[#fn:r1359|1359]]</sup> ) because they are not replicated in other surface, satellite and model datasets (Brown and Derksen, 2013 <sup>[[#fn:r1360|1360]]</sup> ; Mudryk et al., 2017 <sup>[[#fn:r1361|1361]]</sup> ).

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