Near-future climate change over Europe with focus on Croatia in an ensemble of regional climate model simulations

The RegCM climate model was used at a 35 km resolution to downscale the 3-member global ECHAM5/MPI-OM ensemble based on the IPCC A2 scenario covering the European-Mediterranean domain. Within the reference climate (1961-1990), the model high 2 m temperatures (T2m) were reduced and low temperatures were increased relative to verification in a large portion of the domain. Precipitation was underestimated in summer over the Mediterranean region but was overestimated over western Europe in winter, probably due to excessive westerlies in the global model. When RegCM was forced by ERA-40, the dominant errors in the summer T2m appear to be genuine RegCM errors, but a large fraction of errors in winter precipitation was imported from the lateral boundaries. In the near future (2011-2040), the summer T2m is projected to increase by +1.8 degrees C over southwest Europe. The simulated change in precipitation is small and is significant only in regions around the Mediterranean. The wetter north and drier south, a major feature in projections of the European winter climate in the late 21st century, is not predicted for the near future. Similarly, summer drying is confined to western Europe in contrast to nearly continental scale drying observed in projections of the late 21st century. This finding may influence the approaches for adaptation to climate change in the first half and at the end of this century. The effects of downscaling at small scales are analysed for the case of Croatia. The spatial distribution of the number of days with extreme T2m and precipitation in RegCM is consistent with observations. However, this metric is generally underestimated, indicating that over complex orography, even higher horizontal resolution is needed to better resolve climate extremes.