Post‐Processed <scp>CMIP6</scp> Climate Projections for Hydro‐Environmental Risk Assessment in the Middle East and Central Asia

ABSTRACT The estimation of future water resources availability, which depends on runoff, precipitation, temperature and evapotranspiration over medium to long‐term time, is an essential facet of regional climate impact analysis and risk estimation. Especially the Middle East (ME) and Central Asia (CA), which are among the most water scarce regions globally, have largely reached the limit of sustainably usable water across their river basins and ecosystems. A steadily growing water demand driven by irrigation in conjunction with structural water resource limitation bears considerable potential for regional tensions on water allocation. Any strategy designed to mitigate such risks requires foremost a plausible estimation of future water availability trends to allow sensible decision‐making on controlling water use across affected regions. This concerns irrigation practices and management of large reservoirs. During the last two decades, access to multiple Earth‐System Models (ESM) has allowed to generate multi‐model ensemble output for probabilistic climate projections. These projections have only been marginally exploited for decision support on risk mitigation for water resources. Here we describe a comprehensive data product of post‐processed precipitation, temperature and evapotranspiration projections for the 21st century at monthly temporal and half to quarter degree spatial resolutions. The data are obtained by merging the ensemble output of multiple CMIP6 ESMs, after bias correction and variance adjustment over the retrospective 1979–2014 baseline period. The product also issues credibility intervals for quantifying uncertainty and can be used for a variety of hydrological applications, for example to generate future projections of surface runoff and agricultural water use.