Temperature, precipitation and extreme events during the last century in Italy

The paper summarises activities within a broad-based research program for the reconstruction of the evolution of Italian climate in the twentieth century. The main result of the program is that Italian climate is becoming warmer and drier. The decrease of precipitation depends on the reduction in the number of wet days, as precipitation intensity displays a positive trend. Moreover, there is a tendency both toward an increase of heavy precipitation events and long dry spells. Most of the observed signals appear to be due to changes in atmospheric circulation causing an increase in the frequency of subtropical anticyclones over the western Mediterranean basin. This hypothesis is also supported by the evolution of Italian total cloud amount in the 1951–1996 period.