GCM Selection & Ensemble Design: Best Practices and Recommendations from the EURO-CORDEX Community

High resolution climate information is critical for the research community and the downstream vulnerability, impacts, adaptation, and climate services communities (VIACS). Coordinated ensembles generated by initiatives such as the World Climate Reseaerch Program's Coodinated Regional Downscaling Experiments (CORDEX) provide consistent and comparable information for the present as well as future scenarios. CORDEX is the initiative responsible for delivering regional climate data over fourteen different domains encompassing all land areas of the globe. And its output forms the basis for downstreams impacts assessments, adaptation planning and climate services development. This talk will focus on the European CORDEX initiative (hereafter EURO-CORDEX), an established framework of European regional climate modelers, and its coordinated effort to build regional climate ensembles for the years to come. In its first phase (2014 until now), EURO-CORDEX produced a rich ensemble of regional climate simulations under different representative concentration pathway scenarios. The EURO-CORDEX dataset is hosted in global and European databases and fed into the Regional Atlas of 6^th IPCC Assessment Report. However, this ensemble and others like it suffered from several shortcomings, which the community seeks to address in the next phase of production. Chief among these is the oft cited criticism that the selection of GCMs that provide input to the regional climate models was not robust and that the resulting ensemble represents an “ensemble of opportunity”. Here we will show how the community has addressed these shortcomings and present a toolkit, which can be used for evaluating the suitability of GCMs for downscaling. The utility of this toolkit extends well beyond the regional climate and VIACS communities to include researchers interested in researching model biases, constraining future change and exploring so-called future storylines. The toolkit is open-source and the community encourages contributions and sugestions for imporvement. Therefore a short tutorial is also included as part of this talk.