The collaboration between the Coordinated Regional Climate Downscaling Experiment
(CORDEX) and the Earth System Grid Federation (ESGF) provides open access to an unprecedented
ensemble of regional climate model (RCM) simulations, across the 14 CORDEX continental-scale
domains, with global coverage. These simulations have been used as a new line of evidence to as-
sess regional climate projections in the latest contribution of the Working Group I (WGI) to the IPCC
Sixth Assessment Report (AR6), particularly in the regional chapters and the Atlas. Here, we present
the work done in the framework of the Copernicus Climate Change Service (C3S) to assemble a
consistent worldwide CORDEX grand ensemble, aligned with the deadlines and activities of IPCC
AR6. This work addressed the uneven and heterogeneous availability of CORDEX ESGF data by
supporting publication in CORDEX domains with few archived simulations and performing quality
control. It also addressed the lack of comprehensive documentation by compiling information from
all contributing regional models, allowing for an informed use of data. In addition to presenting
the worldwide CORDEX dataset, we assess here its consistency for precipitation and temperature
by comparing climate change signals in regions with overlapping CORDEX domains, obtaining
overall coincident regional climate change signals. The C3S CORDEX dataset has been used for
the assessment of regional climate change in the IPCC AR6 (and for the interactive Atlas) and is
available through the Copernicus Climate Data Store (CDS).
Javier Diez-Sierra, Maialen Iturbide, José M. Gutiérrez, Jesús Fernández,
Josipa Milovac, Antonio S. Cofiño, Ezequiel Cimadevilla, Grigory Nikulin,
Guillaume Levavasseur, Erik Kjellström, Katharina Bülow, András Horányi,
Anca Brookshaw, Markel García-Díez, Antonio Pérez, Jorge Baño-Medina,
Bodo Ahrens, Antoinette Alias, Moetasim Ashfaq, Melissa Bukovsky, Erasmo
Buonomo, Steven Caluwaerts, Sin Chan Chou, Ole B. Christensen, James M. Ciarlò,
Erika Coppola, Lola Corre, Marie-Estelle Demory, Vladimir Djurdjevic, Jason P. Evans,
Rowan Fealy, Hendrik Feldmann, Daniela Jacob, Sanjay Jayanarayanan, Jack Katzfey,
Klaus Keuler, Christoph Kittel, Mehmet Levent Kurnaz, René Laprise, Piero Lionello,
Seth McGinnis, Paola Mercogliano, Pierre Nabat, Barış Önol, Tugba Ozturk,
Hans-Jürgen Panitz, Dominique Paquin, Ildikó Pieczka, Francesca Raffaele, Armelle
Reca Remedio, John Scinocca, Florence Sevault, Samuel Somot, Christian Steger,
Fredolin Tangang, Claas Teichmann, Piet Termonia, Marcus Thatcher, Csaba Torma,
Erik van Meijgaard, Robert Vautard, Kirsten Warrach-Sagi, Katja Winger, and
George Zittis. The Worldwide C3S CORDEX Grand Ensemble: A Major Contribution to Assess Regional Climate Change in the IPCC AR6 Atlas
Journal: BAMS, Volume: 103, Year: 2022, First page: E2804, Last page: E2826, doi: https://doi.org/10.1175/BAMS-D-22-0111.1