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

==== [[#Atlas.5.5.4|Atlas.5.5.4]] Assessment and Synthesis of Projections ====

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Temperature and precipitation projections from CMIP5/CMIP6 and CORDEX for different GWLs, SSP and RCP scenarios, time periods and baselines are shown in Figure Atlas.1 7 and further details can be explored in the Interactive Atlas.

In WCA, projections for different GWLs are consistent not only in annual and seasonal warming but in the ranges of the projections. Under RCP8.5, annual mean temperature will ''likely'' exceed 2°C by mid-century (compared with 1995–2014) and reach up to 4.8°C–6°C by the end of the century ( [[#Yang--2017|Yang et al., 2017]] ), with faster warming projected by the CMIP6 ensemble under SSP5-8.5. In individual county-level studies on GCM future climate projections, temperatures increased by up to 7°C by the end of the century, depending on season and emissions scenario ( [[#Allaberdiyev--2010|Allaberdiyev, 2010]] ; [[#MENRPG--2015|MENRPG, 2015]] ; [[#MNP--2015|MNP, 2015]] ; [[#Gevorgyan--2016|Gevorgyan et al., 2016]] ; [[#Osborn--2016|Osborn et al., 2016]] ; [[#Aalto--2017|Aalto et al., 2017]] ; [[#IDOE--2017|IDOE, 2017]] ; [[#Salman--2017|Salman et al., 2017]] ). Statistical downscaling of 18 CMIP5 GCMs projected an annual temperature increase of 0.37°C per decade (under RCP4.5) with the maximum in northern WCA and warming most conspicuous in summer ( [[#Luo--2019|Luo et al., 2019]] ). RCM downscaling of GCMs over Central Asia projected a larger increase of temperature under RCP8.5 for the 2071–2100 period, ranging from 5°C to 8°C ( [[#Ozturk--2017|Ozturk et al., 2017]] ).

In ARP, the projected change in ensemble mean annual temperature from 30 CMIP6 models is from 1.6°C (SSP1-2.6) to 5.3°C (SSP5-8.5) by 2070–2099 compared to 1981–2010 ( [[#Almazroui--2020a|Almazroui et al., 2020a]] ). The projected warming is the highest in the north, reaching 5.9°C and lowest in the south (4.7°C). COSMO-CLM projections over the CORDEX-MENA domain show for ARP and WCA a strong warming with marked seasonality for the end of the 21st century, ranging from 2.5°C in winter under RCP4.5 to 8°C in summer under RCP8.5 and with large increases found over high-altitude areas in winter and spring ( [[#Bucchignani--2018|Bucchignani et al., 2018]] ; [[#Ozturk--2018|Ozturk et al., 2018]] ). The CMIP5 multi-model mean warming in boreal summer in 2070–2099, compared with 1951–1980, is projected to be about 2.5°C and 6.5°C at the 2°C and 4°C global warming levels respectively ( [[#Huang--2014|Huang et al., 2014]] ).

Future projections of precipitation in South West Asia have large uncertainties and thus ''low confidence'' . There are few significant changes, little consensus on the sign and with a tendency for reduction in CMIP5 being reversed in CMIP6 across all warming levels ( [[#Ozturk--2018|Ozturk et al., 2018]] ). Statistical downscaling of 18 CMIP5 GCMs under RCP4.5 projected an increase in precipitation of 4.6 mm per decade in South West Asia during 2021–2060 relative to 1965–2004 ( [[#Luo--2019|Luo et al., 2019]] ). CMIP5 simulations project a general decrease in precipitation over lowlands in Turkey, Iran, Afghanistan and Pakistan ( [[#Ozturk--2017|Ozturk et al., 2017]] ), and an increase over high-mountain regions ( [[#Aalto--2017|Aalto et al., 2017]] ; [[#Salman--2018|Salman et al., 2018]] ). At a 4°C global warming level, the multi-model mean annual precipitation for Turkmenistan and parts of Tajikistan and Uzbekistan is projected to decrease by 20%, with somewhat stronger relative decreases in summer ( [[#Reyer--2017|Reyer et al., 2017]] ). Over northern WCA, the CMIP5 ensemble mean projects increases of over 3 mm per decade under RCP2.6 and over 6 mm per decade under RCP4.5 and RCP8.5 over the 21st century ( [[#Huang--2014|Huang et al., 2014]] ). Mean annual precipitation is projected to rise by 5.2% at the end of the 21st century (2070–2099) under RCP8.5, compared to 1976–2005, while mean annual snowfall is projected to decrease by 26.5% in Central Asia ( [[#Yang--2017|Yang et al., 2017]] ). However, regardless of the sign of the precipitation change in the high-mountain regions of Central Asia, the influence of the warming on the snowpack will ''very likely'' cause important changes in the timing and amount of the spring melt ( [[#Diffenbaugh--2013|Diffenbaugh et al., 2013]] ).

In ARP, the projected change in ensemble mean annual precipitation from 30 CMIP6 models ranges from 3.8% (–2.6 to 28.8%) to 31.8% (12.0–106.5%) under SSP1-2.6 and SSP5-8.5 emissions for the period 2080–2100 compared with 1995–2014 ( [[#Almazroui--2020a|Almazroui et al., 2020a]] ). North-west ARP precipitation is projected to decrease between –6 to –27% per decade and in the south precipitation to increase by up to 8.6% per decade. CMIP6 projections are in line with those from CMIP3 and CMIP5, however they are less variable in the central area in CMIP6. The uncertainty associated with precipitation over ARP is large because of very low annual amounts and high variability.

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