The Worldwide C3S CORDEX Grand Ensemble: A Major Contribution to Assess Regional Climate Change in the IPCC AR6 Atlas

Abstract The collaboration between the Coordinated Regional Climate Downscaling Experiment (CORDEX) and Earth System Grid Federation (ESGF) provides open access to an unprecedented ensemble of regional climate model (RCM) simulations, across 14 CORDEX continental-scale domains, with global coverage. These simulations have been used as a new line evidence assess projections in latest contribution Working Group I (WGI) IPCC Sixth Assessment Report (AR6), particularly chapters Atlas. Here, we present work done framework Copernicus Change Service (C3S) ­assemble consistent worldwide grand ensemble, aligned deadlines ­activities AR6. This addressed uneven heterogeneous availability ESGF data by supporting publication domains few archived performing quality control. It also lack comprehensive documentation compiling information from all contributing models, allowing for informed use data. In addition presenting dataset, here its consistency precipitation temperature comparing change signals regions overlapping obtaining overall coincident signals. C3S dataset has assessment AR6 (and interactive Atlas) is available through Data Store (CDS).