The worldwide C3S CORDEX grand ensemble: A major contribution to assess regional climate change in the IPCC AR6 Atlas

Thursday, December 29, 2022

Together with the Santander Meteorology Group and many other institutions, we contributed to (yet) another article related to the IPCC Sixth Assessment Report. In this case, the paper describes a new dataset called the worldwide C3S CORDEX grand ensemble. The work, entitled The Worldwide C3S CORDEX Grand Ensemble: A Major Contribution to Assess Regional Climate Change in the IPCC AR6 Atlas, has been published in the Bulletin of the American Meteorological Society journal in open access mode.

This dataset constitutes a very significant improvement with respect to the CORDEX regional model climate projection data already available in the Earth System Grid Federation (ESGF). The following are the most important improvements.

  • Several groups received support to publicate new data from their CORDEX domains. After making a comprehensive inventory of the available data, several regions were identified where the available projections were too few, and different groups were contacted to help them to publish more simulations.
  • Quality control of the data was performed. This was where the co-authors from Predictia contributed.
  • Comprehensive documentation was compiled from all contributing regional models by contacting all the groups that produced the data. This fills a significant gap and will let the users make better informed decisions.
  • Consistency for climate change signals in regions with overlapping CORDEX domains was assessed. Results are summarised in the paper, and show overall consistent signals.

This dataset is available for download in the Copernicus Climate Change Service (C3S) Data Store (CDS) and can be visualised in the IPCC WGI Interactive Atlas.

The paper abstract is presented below:

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 assess 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).

Figure credits: © AMS 2022