Evolution of rainfall in Italy over the last 200 years: Interactions between climate indices and global warming

Abstract

This study contributes to a better understanding of past climate variability and mesoscale dynamics in the Mediterranean Basin, a region with notable sensitivity to climate change.We investigate the variations of rainfall amount and intensity by analyzing centenary time series in Italy. The study area offers an ideal setting for analyzing these dynamics due to its unique geographical position. The rainfall time series are compared to the climate indices time series to understand the influences of the mesoscale atmospheric teleconnections and of the possible changes in rainfall regimes due to an increase of the sea surface temperatures. The study is conducted by applying statistical methods on more than 100 time series. The results show that most regions of Italy have been affected by a decrease in rainfall amount and an increase in rainfall intensity over the last 200 years. This work also highlights that these patterns are correlated to positive phases of the North Atlantic Oscillation and to an increase in sea surface temperatures. The trends of climate indices thus suggest a decrease in the amount and an increase in the intensity of future rainfall distribution, with severe consequences in terms of water availability and geo-related risks.