Recent Extremes in European Climate: Assessment, Case Studies and Impacts

During the last centuries and up to the present decade, extreme climate events have certainly had larger economic impacts than any trend of temperature in Europe. In addition to an intrinsic scientific interest, their study is thus essential for society. One of the challenges of their investigation is that, depending on their definition, extreme climate events potentially have a behavior that is not connected to the secular temperature trend in a simple fashion. This presentation will review the statistical assessments of extremes in Europe, focusing on surface temperature, precipitation, and their connections with large-scale features of the atmospheric circulation. In particular, the questions of modeling their severity and frequency will be discussed in the first part of the presentation. I will then give two kinds of examples of European climate extremes: summer heatwaves and droughts, and winter warm waves. The mechanisms leading to such phenomena will be explored, and I will examine some of the impacts on the biosphere that were recently observed. In order to provide a long term perspective of those events, examples of historical droughts in France will be presented and connected with proxy records of temperature. It appears that the mechanisms that are favored for present-day climate might still have been valid during the past centuries. To conclude, new challenges for dynamical and statistical modeling will be explored.