How does the CMIP6 ensemble change the picture for European climate projections?

Abstract

We compare Coupled Model Intercomparison Project (CMIP) ensemble (CMIP6) projections for seasonal mean temperature and precipitation to CMIP5 for northern Europe, central Europe and the Mediterranean. The CMIP6 ensemble shows increased projected summer warming compared to CMIP5, which was found to be statistically significant in central Europe and the Mediterranean. Precipitation projections for Central Europe in CMIP6 were found to have a stronger drying trend in the summer months, there was also a substantially narrower projection range. Spatial comparisons indicate that this stronger drying trend also extends into a large part northern Europe. We show that warmer projected summer temperatures in northern Europe and the Mediterranean are largely driven by the higher global climate sensitivities in CMIP6 models, while regional changes are broadly similar. In central Europe a significant difference in the regional responses was found and in these cases the picture can be said to have changed. We find the difference in regional sensitivity is important in central Europe where it accounts for roughly 40 of the differences between ensembles in projected regional temperature.