Selection of a sub-ensemble of CMIP6 projections for the EDF in-house climate service

As a power company, EDF must adapt its activities and assets to the ongoing climate change. EDF/R&D has been involved in climate research for a long time and giving the ever-growing number of climate impact studies to conduct, it has been decided in 2014 to create an in-house climate service. This service is meant as a bridge between the scientific community and EDF’s operational needs. It relies on three main pillars: data, tools and expertise.

With the availability of the new CMIP6 climate projections and the huge amount of data involved, the question of the choice of projections to be downloaded has arisen. It has been studied in collaboration with the CERFACS global change team. Using a set of criteria, a sub-ensemble of around 20 climate models with four emission scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5) has been selected. The criteria are the following:

• availability of the necessary variables at the daily timescale
• available projections for the 4 scenarios
• consideration of model dependencies and Equilibrium Climate Sensitivity
• representation of the ensemble spread in terms of climate response
• model performance across France

Models with an ECS inside the very likely range of observed climate sensitivity estimated in IPCC AR6 are preferred, while one or two higher sensitivity models are also selected as “low likelihood high impact” scenarios, used for the most sensitive assets.

Once all the projections have been retrieved, this database stands as the reference database for all EDF impact studies. Then, depending on the impact study, a further step of sub-sampling inside the database may be necessary.

The selection will be presented and motivated, together with some examples of use in impact studies, with or without further sub-sampling.