Climate shifts the timing of European floods

In order to understand the connection between climate and floods, external pageProf. Blöschl of TU Viennacall_made and colleagues from 30 research institutions in Europe looked closely at the timing of the largest annual flood events in different regions of Europe. Flood data from over 4700 stations across Europe were meticulously compiled, screened and statistically analysed. The results show that floods in Europe have indeed shifted considerably over the last 50 years. In north-eastern Europe, Sweden, Finland and the Baltic States, floods now tend to occur one month earlier than in the 1960s and 1970s because of earlier snowmelt due to a warming climate. On the other hand, in parts of northern Britain, western Ireland, coastal Scandinavia and northern Germany, floods now tend to occur on the average about two weeks later than they did a couple of decades ago, due to later winter storms. The signal for Switzerland and the Alpine region is less pronounced, with smaller shifts in timing affecting floods south of the Alps caused by autumn heavy rainfall and north of the Alps caused by changes in snow accumulation and melt due to a warmer climate. The research also focussed on selected hotspots in Europe, where changes in the timing of floods were shown to follow closely one of the three main hydrological triggers, i.e. heavy rainfall, snowmelt, soil saturation. The ETH contributors to the research team were Peter Molnar and Paolo Burlando of the Institute of Environmental Engineering, who research climate change effects on floods in Switzerland within the National Center for Climate Services Hydro-CH2018 Project Climate Change and its consequences on Hydrology in Switzerland funded by BAFU.

Blöschl, G. et al. (2017) external pageChanging climate shifts timing of European floodscall_made. Science, 357(6351), 588-590, doi:10.1126/science.aan2506