A global perspective on western Mediterranean precipitation extremes

The Mediterranean region has been declared a climate change hotspot due, among other reasons, to an expected increase in the torrential rains that frequently affect this densely populated area. However, the extent to which these torrential rains are connected to other regions outside the Mediterranean remains uncertain. Here we simulate 160 extreme precipitation events with an atmospheric model enabled for state-of-the-art moisture tracking and demonstrate that large scale moisture transport is a more important factor than evaporation over local sources. We find that the average precipitation fraction with source in the Mediterranean is only 35%, while 10% is from evapotranspiration over nearby land in continental Europe and 25% originates in the North Atlantic. The remaining 30% comes from several more distant source regions, sometimes as remote as the tropical Pacific or the Southern Hemisphere, indicating direct connections with multiple locations on the planet and a global scale energy redistribution. Our results point to the importance of approaching these extreme episodes from a more global rather than purely regional perspective, especially when attempting to attribute them to climate change.