Questions related to the existing networks of climate model cooperations and which climate model projections to use.
What is CMIP?
CMIP stands for the Coupled Model Intercomparison Project and is a joint global collaboration between climate modelers organized under WCRP (the World Climate Research Program) of WMO (World Meteorological Organization).
CMIP is now in its sixth phase (Eyring et al., 2016) and results from CMIP6 have been assessed in the IPCC AR6 reports. Similarly, CMIP5 (Taylor et al., 2012) was assessed in the IPCC AR5 reports.
Results from CMIP5/CMIP6 can be accessed in the C3S Climate Data Store (CDS) at https://cds.climate.copernicus.eu/#!/search?text=cmip5
and https://cds.climate.copernicus.eu/cdsapp#!/dataset/projections-cmip6
What is CORDEX?
CORDEX stands for the Coordinated Regional climate Downscaling EXperiment and is a joint global collaboration under the WCRP of WMO.
The CORDEX vision is to advance and coordinate the science and application of regional climate downscaling through global partnerships.
For Europe, in particular, CORDEX is organized in EURO-CORDEX (https://euro-cordex.net/) and Med-CORDEX (https://www.medcordex.eu/).
Results from CORDEX (all 14 CORDEX domains) can be accessed in the CDS at https://cds.climate.copernicus.eu/cdsapp#!/dataset/projections-cordex-domains-single-levels
Which data should I use, CMIP-data or CORDEX-data?
The answer strongly depends on the question that you want to answer. The CORDEX-data adds value to the CMIP-data as the regional climate models are run at higher horizontal resolution. This can be of particular importance for assessing changes in extremes. CMIP-data, on the other hand, represent a more comprehensive data set in the number of projections for the future. This means that CMIP-data may be better suited for assessing what is robust and what is more uncertain related to future climate change. Ideally, both data sets should be used simultaneously to address both questions.
References
Eyring V, Bony S, Meehl GA, Senior CA, Stevens B, Stouffer RJ and Taylor KE (2016) Overview of the Coupled Model Intercomparison Project Phase 6 (CMIP6) experimental design and organization Geosci. Model Dev. 9, 1937–58.
Taylor KE, Stouffer RJ and Meehl GA (2012) An overview of CMIP5 and the experiment design Bull. Am. Meteor. Soc. 93 485–98