Brief Communication: Drivers of the recent warming of the Mediterranean Sea, and its implications for hail risk

Abstract. The Mediterranean Sea has warmed by about 2 K since the early 1980s, and this heating intensifies damage from moisture-driven perils such as hailstorms and floods in continental Europe via the basic thermodynamic effect. This study uses the DAMIP (Detection and Attribution Model Intercomparison Project) set of climate model experiments to explore the drivers of the recent Mediterranean warming. The models simulate the observed multidecadal variations of Mediterranean Sea temperatures in the modern period accurately, and indicate anthropogenic aerosol forcing was largely responsible for the cooler period from about 1900 to the late 1970s, while rising greenhouse gases are the main cause of warming waters since then. Next, we reviewed trends in damaging hail, and found they have been increasing by around 2 % yr−1 in key parts of mainland Europe since 1980. The rising risk fits with the established mechanism whereby warmer waters moisten low-level air leading to more severe thunderstorm hazards, though the exact relation between a warming Mediterranean and hail loss growth remains uncertain. Anthropogenic forcings will continue warming the Mediterranean for the next couple of decades at least, suggesting further increases to hail damages in high-risk parts of Europe.