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

===== 3.4.3.1.2 Energy budget =====

Warming induced reductions in the duration and extent of Arctic spring snow cover (Section 3.4.1.1) lower albedo because snow-free land reflects much less solar radiation than snow. The corresponding increase in net radiation absorption at the surface provides a positive feedback to global temperatures (Flanner et al., 2011 <sup>[[#fn:r1624|1624]]</sup> ; Qu and Hall, 2014 <sup>[[#fn:r1625|1625]]</sup> ; Thackeray and Fletcher, 2016 <sup>[[#fn:r1626|1626]]</sup> ) ( ''high confidence'' ). Estimates of increases in global net solar energy flux due to snow cover loss range from 0.10–0.22 W m –2 (± 50%; ''medium confidence'' ) depending on dataset and time period (Flanner et al., 2011 <sup>[[#fn:r1627|1627]]</sup> ; Chen et al., 2015 <sup>[[#fn:r1628|1628]]</sup> ; Singh et al., 2015 <sup>[[#fn:r1629|1629]]</sup> ; Chen et al., 2016b <sup>[[#fn:r1630|1630]]</sup> ). Sources of uncertainty include the range in observed spring snow cover extent trends (Hori et al., 2017 <sup>[[#fn:r1631|1631]]</sup> ) and the influence of clouds on shortwave feedbacks (Sedlar, 2018 <sup>[[#fn:r1632|1632]]</sup> ; Sledd and L’Ecuyer, 2019 <sup>[[#fn:r1633|1633]]</sup> ). Terrestrial snow changes also affect the longwave energy budget via altered surface emissivity (Huang et al., 2018 <sup>[[#fn:r1634|1634]]</sup> ). Climate model simulations show that changes in snow cover dominate land surface related positive feedbacks to atmospheric heating (Euskirchen et al., 2016 <sup>[[#fn:r1635|1635]]</sup> ), but regional variations in surface albedo are also influenced by vegetation (Loranty et al., 2014 <sup>[[#fn:r1636|1636]]</sup> ). There is evidence for positive sensitivity of surface temperatures to increased northern hemisphere boreal and tundra leaf area index, which contributes a positive feedback to warming (Forzieri et al., 2017 <sup>[[#fn:r1637|1637]]</sup> ).

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