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

==== [[#Atlas.5.2.2|Atlas.5.2.2]] Assessment and Synthesis of Observations, Trends and Attribution ====

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Increases in surface air temperature (SAT) have been observed since the mid-1970s over the whole of North Asia ( [[#Frolov--2014|Frolov et al., 2014]] ), and particularly over the north-eastern part (Figure Atlas.11; [[#Gruza--2015|Gruza et al., 2015]] ). Trends of annual SAT in the northern part of the region during the last decades were ''very likely'' twice as strong as the global average (Figure Atlas.11; [[#Frolov--2014|Frolov et al., 2014]] ; [[#Mokhov--2015|Mokhov, 2015]] ; [[#Sherstyukov--2016|Sherstyukov, 2016]] ) with trends in RFE of 0.8°C–1.2°C per decade for the 1976–2014 period and more intense warming strengthening from south to north observed in spring in ESB ( [[#Frolov--2014|Frolov et al., 2014]] ; [[#Ippolitov--2014|Ippolitov et al., 2014]] ; [[#Kokorev--2015|Kokorev and Sherstiukov, 2015]] ).

Recent strong warming in polar regions (Section [[#Atlas.11.2|Atlas.11.2]] ) was accompanied by cooling in winter in mid-latitude regions particularly in the southern part of WSB and ESB ( [[#Cohen--2014|Cohen et al., 2014]] ; [[#Ippolitov--2014|Ippolitov et al., 2014]] ; [[#Gruza--2015|Gruza et al., 2015]] ; [[#Kharyutkina--2016|Kharyutkina et al., 2016]] ; [[#Overland--2016|Overland et al., 2016]] ; [[#Perevedentsev--2017|Perevedentsev et al., 2017]] ; [[#Wegmann--2018|Wegmann et al., 2018]] ). These temperature decreases were strongly correlated with significant warming over the Barents-Kara Sea (greater than 2.5°C per decade during 2003–2017) and sea ice loss, suggesting a causal link ( [[#Outten--2012|Outten and Esau, 2012]] ; [[#Semenov--2012|Semenov et al., 2012]] ; [[#Overland--2016|Overland et al., 2016]] ; [[#Semenov--2016|Semenov, 2016]] ; [[#Wegmann--2018|Wegmann et al., 2018]] ; [[#Meleshko--2019|Meleshko et al., 2019]] ; [[#Susskind--2019|Susskind et al., 2019]] ), though recent studies ( [[#Blackport--2019|Blackport et al., 2019]] ; [[#Clark--2019|Clark and Lee, 2019]] ) have shown that both phenomena result from mid-latitude circulation variability (see also Cross-Chapter Box 10.1). In addition, significant warming in the last decade has halved the cooling trend in southern WSB from –0.6°C per decade during 1976–2012 to –0.3°C per decade during 1976–2018 ( ''high confidence'' ) ( [[#Frolov--2014|Frolov et al., 2014]] ; [[#Roshydromet--2019|Roshydromet, 2019]] ).

Annual precipitation totals ''very likely'' increased over North Asia in the last half century along with more heavy and less light precipitation, more freezing rain and less freezing drizzle (Figure Atlas.11 and the Interactive Atlas; [[#Wen--2014|Wen et al., 2014]] ; [[#Groisman--2016|Groisman et al., 2016]] ; [[#Ye--2017|Ye et al., 2017]] ; [[#Chernokulsky--2019|Chernokulsky et al., 2019]] ). The highest increase was observed over regions of Siberia and RFE with estimated trends of 10–25 mm per decade for the 1976–2014 period ( [[#Kokorev--2015|Kokorev and Sherstiukov, 2015]] ) or 5% per decade for the 1976–2018 period ( [[#Roshydromet--2019|Roshydromet, 2019]] ). Increases over southern RFE are the largest (over 50 mm per decade) and are mostly due to positive changes in convective precipitation intensity in the region in the summer season (JJA) during 1966–2016 ( ''medium confidence'' ) ( [[#Chernokulsky--2019|Chernokulsky et al., 2019]] ). A decreasing trend was observed in central WSB, northern ESB, the Baikal and Transbaikal regions, the Amur River region, and Primorie territories of RFE (the Kamchatka and Chukchi peninsulas) with up to –20 mm per decade for the 1976–2014 period ( [[#Kokorev--2015|Kokorev and Sherstiukov, 2015]] ) or 15–20% per decade for the 1976–2018 period ( [[#Roshydromet--2019|Roshydromet, 2019]] ). Overall, solid precipitation predominantly decreased in North Asia and ''very likely'' caused both less snow cover extent (SCE) and snow water equivalent (SWE), attributable to the anthropogenic influence with ''high confidence'' (Sections 2.3.2.2 and 3.4.2).

Snow characteristics depend on both temperature and precipitation, and observed trends over North Asia show large spatial heterogeneity and interannual variability (Figure Atlas.1 8) leading to ''medium confidence'' that maximum snow depth has increased over Siberia, the Okhotsk Sea coast and in southern RFE since the 1960s ( [[#Callaghan--2011|Callaghan et al., 2011]] ; [[#Loginov--2014|Loginov et al., 2014]] ), with trends during 1976–2016 of 1.8 cm (in WBS), 1.1 cm (in ESB), and 4.6 cm (in RFE) per decade ( [[#Bulygina--2017|Bulygina et al., 2017]] ). Snow cover duration increased in Yakutia, Sakhalin Island and some other coastal areas of the Pacific Ocean in RFE during 1980–2009 ( [[#Callaghan--2011|Callaghan et al., 2011]] ), and decreased in WSB and ESB ( [[#Bulygina--2017|Bulygina et al., 2017]] ; [[#Roshydromet--2019|Roshydromet, 2019]] ). However, [[#Gorbatenko--2019|Gorbatenko et al. (2019)]] reported that in south-eastern WSB maximal snow depth has increased by 5–20 cm and duration of steady snow cover by between 4 and 10 days during 1989–2016 (Figure Atlas.1 8).

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[[File:73294f618704ec90a160056e6f9d1cde IPCC_AR6_WGI_Atlas_Figure_18.png]]

'''Figure Atlas.18''' '''|''' '''Linear trends for the 1980–2015 period based on station data from the World Data Centre of the Russian Institute for Hydrometeorological Information''' (RIHMI-WDC; [[#Bulygina--2014|Bulygina et al., 2014]] ). '''(a)''' Snow-season duration from 1 July to 31 December (days per decade); '''(b)''' snow-season duration from 1 January to 30 June (days per decade); '''(c)''' maximum annual height of snow cover (mm per decade). Trends have been calculated using ordinary least squares regression and the crosses indicate non-significant trend values (at the 0.1 level) following the method of [[#Santer--2008|Santer et al. (2008)]] to account for serial correlation. Further details on data sources and processing are available in the chapter data table (Table Atlas.SM.15).

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