Extremes and anthropogenic climate change in the Mediterranean basin.

Climatic and meteorological extremes are a broad and diverse category of phenomena, generally defined on the basis of low probability, which have negative consequences on ecosystems and societies. Climate change has already impacted extreme temperatures and, in addition to further increasing heatwaves, is expected to increase the intensity of extreme rainfall, droughts and coastal flooding. Different processes are responsible for varying different extremes. However, the increase in saturation water pressure as a function of temperature in the atmosphere plays a role in many of them. The increased evaporative capacity of a warmer atmosphere increases evapotranspiration from the continental surface and in combination with reduced precipitation results in longer and more intense ecological droughts (lack of moisture in the soil). This in turn exerts a positive feedback on heatwaves by reducing evapotranspiration cooling of continental surfaces. The higher water content of a warmer atmosphere is also the basis for the increase in extreme precipitation. This communication analyses these processes and their relevance in the Mediterranean basin.