Diverging trends in large floods across Europe in a warming climate

Abstract Large floods, which affect multiple regions simultaneously, pose substantial risks to lives and economies. In a warmer climate, increased precipitation extremes and reduced snowmelt are expected to alter flood characteristics, but how the dynamics of large floods across Europe will evolve under climate change remains unclear. By jointly assessing projected changes in the timing, spatial extent and volume of large floods in a warmer world, here we show that earlier snowmelt generally leads to earlier floods, while increasing precipitation contributions attenuate flood seasonality. Although continental-scale averages suggest limited change, they mask substantial regional heterogeneity. In western Europe, projected increases in heavy precipitation result in larger flood extents and volumes. In contrast, reduced snowmelt dominates changes in the largest floods in northern Europe, with localized shifts from snowmelt-driven to rainfall-driven floods. These regionally diverse responses of large floods to climate change should be considered in transnational flood risk management across Europe.