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

==== [[#Atlas.5.5.5|Atlas.5.5.5]] Summary ====

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Increases in annual surface air temperature over South West Asia are ''very likely'' in the range of 0.24°C–0.81°C per decade over the last 50–60 years. Annual precipitation change over ARP since 1970 is estimated at –6.3 mm per decade (and in the range of –30 to 16 mm per decade) and over WCA is generally not significant except over the elevated part of eastern WCA where increases between 1.3 mm and 4.8 mm per decade during 1960–2013 have been observed ( ''very high confidence'' ). In mountainous areas, the scarcity and decline of the number of observation sites since the end of the former Soviet Union in 1991 increase the uncertainty of the long-term temperature and precipitation estimates ( ''high confidence'' ).

Mean temperature biases in RCMs are within ±3°C in South West Asia, and annual precipitation biases are positive in almost all parts of the region, except over the ARP where they are negative in the wet season (November to April) and over WCA in winter and spring (from December to May) ( ''medium confidence'' ). Since regional model evaluation literature has only recently emerged there is ''medium evidence'' about the performance of RCMs in South West Asia though with ''medium'' to ''high agreement'' on mean temperature and precipitation biases. RCMs simulate colder temperatures than observed over mountainous and high plateau regions ( ''limited evidence'' , ''high agreement'' ).

Further warming over South West Asia is projected in the 21st century to be greater than the global average, with rates varying from 0.25°C to 0.8°C per decade depending on the season and scenario, and the maximum rates found in the northern part of the region in summer ( ''high confidence'' ). The influence of the warming on the snowpack will ''very likely'' cause changes in the timing and amount of the spring melt. CMIP6 projected changes in annual precipitation totals are in the range of –3 to 29% (SSP1-2.6) and 12–107% (SSP5-8.5) in ARP ( ''medium confidence'' ). Strong spatio-temporal differences with overall precipitation decreases are projected in the central and northern parts of WCA in summer (JJA) with increases in winter (DJF) ( ''medium confidence'' ).

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