Climate Change Effects on Precipitation Extremes over Europe Evaluated by the Region-of-Influence Method

The study examines precipitation extremes over Europe in an ensemble of regional climate model (RCM) simulations with a 25-km resolution. Precipitation extremes are considered at a wide range of time scales from hourly to multi-day amounts and in winter and summer seasons, and their climate change scenarios are evaluated for the late 21st century time slice (2070-99) against the recent climate (1961-90). The region-of-influence method is applied when estimating distributions of extremes, which leads to spatial patterns that are smoothed compared to local analysis (in which distributions are fitted for each grid box separately). We focus on uncertainties of the climate change scenarios related to differences amongst the RCM simulations. Dependence of the results on the time scale of precipitation aggregation (from hourly to multi-day) is analysed as well. The ensemble-mean scenarios show larger increases in extremes than in mean seasonal precipitation in both seasons, and in summer, increases in extremes are projected even in areas where mean seasonal precipitation declines. The increases in short-term (hourly) extremes tend to be larger than increases in multi-day extremes in both seasons. In spite of some general tendencies found, uncertainties of the climate change scenarios are large, due to large differences among the RCMs as well as biases in reproducing precipitation characteristics for the recent climate and factors that are poorly or not at all represented in the examined RCM ensemble, including future emission scenarios.