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

==== [[#Atlas.5.2.1|Atlas.5.2.1]] Key Features of the Regional Climate and Findings From Previous IPCC Assessments ====

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===== Atlas.5.2.1.1 Key Features of the Regional Climate =====

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North Asia extends from the Ural Mountains in the west to the Pacific Ocean in the east and from the Russian Arctic in the north to West and East Central Asia and East Asia in the south. Its most recognizable features are boreal forests and permafrost. In AR6 North Asia is divided into three reference regions (Figure Atlas.1 7): West Siberia (WSB) with a continental climate, warm summers and cold winters, many waterlogged areas and several natural zones due to a large extent from south to north and heterogeneity in regional climates; East Siberia (ESB) which is mainly highland with extensive permafrost and a more severe continental climate characterized by harsh, long winters and short, hot summers, and by less precipitation and snow cover than in neighbouring regions; and the Russian Far East (RFE) with a monsoon-influenced climate, cold winters and wet summers in the south, and cold winters and cool summers almost without precipitation in the north. WSB and ESB are mainly influenced by NAO and NAM (Annex IV.2.1) and the Arctic Oscillation (AO) with associated atmospheric blocking by the Siberian High (SH) that exhibits a pronounced decadal-to-multi-decadal variability (see also Table Atlas.1). RFE is under the influence of the ENSO (Annex IV.2.3) and the PDV (Annex IV.2.6) that mostly affect rainfall variability.

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===== Atlas.5.2.1.2 Findings From Previous IPCC Assessments =====

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In the previous IPCC assessment cycles, the three sub-regions comprising North Asia in this section, along with Eastern Europe and the Asian Arctic, were considered as either Northern Eurasia or Russia in AR4 and AR5. The AR5 WGI stated that for North and Central Asia CMIP5 models had difficulty in representing climatological means of both temperature and precipitation, which is partly related to the scarceness of observational data in northern parts of the region and to issues related to the estimation of biases with coarse-resolution models ( [[#Christensen--2013|Christensen et al., 2013]] ). In CMIP5 projections under different RCP scenarios, North Asian temperatures increase more in winter (DJF) than summer (JJA; [[#Seneviratne--2012|Seneviratne et al., 2012]] ). With most models projecting increased precipitation significantly above the 20-year natural variability, it was concluded that precipitation in North Asia will ''very likely'' increase ( [[#Christensen--2013|Christensen et al., 2013]] ).

The SRCCL identified aridification of the climate in southern East Siberia between 1976 and 2016 as causing an extension of the steppes polewards whilst climate change also extended the vegetation season, increasing forest productivity in most of boreal Siberia, but increasing risk of wildfire and tree mortality ( [[#Mirzabaev--2019|Mirzabaev et al., 2019]] ). The SROCC noted the warming climate has caused permafrost thaw and loss of ground ice, and thus land subsidence and collapse, disturbing ecosystems and human infrastructure. Permafrost stability, hydrology and vegetation were also impacted by recent extensive fires burning into the organic soil layer ( [[#Meredith--2019|Meredith et al., 2019]] ). The SR1.5 noted that future, higher levels of warming lead to greater impacts in key systems such as the Siberian ecosystems, identified as one of the threatened systems (‘Reason for Concern 1 – RFC1’; [[#Hoegh-Guldberg--2018|Hoegh-Guldberg et al., 2018]] ) with impacts at 2°C expected to be greater than those at 1.5°C ( ''medium confidence'' ).

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