Evidence of climate change in Sicily by means of rainfall data analysis

Abstract Rainfall constitutes an important climatic variable as its lack can lead to severe droughts while its excess can trigger catastrophic events. The Mediterranean basin is one of the European regions most affected by climate change's effects and Sicily island, for its location in the middle of the Mediterranean sea, represents a very interesting place to study climatic variables as for example rainfall trends. Due to its central position and peculiar orography, the seasonal variability of rainfall in this area is connected to the behavior of the surrounding climatic systems, such as the continental and Atlantic ones. Moreover, Sicily displayed unusual rainfall behavior and unexpected extreme precipitation events during the last decades. In this paper we have investigated rainfall data in Sicily from 2002 to 2023, by focusing on seasonal variability, in order to find possible evidences of climate change in the Mediterranean basin. We have performed a data-driven empirical study able to highlight underlying characteristics and trends. No models or hypothesis were a-priori assumed, neither results or data were rejected: raw hourly records were analysed, for the first time. This study provides a complete and clear picture of pluviometric regimes in Sicily from 2002 to 2023, mainly based on graphical visualization. Results show that precipitation variables behave homogeneously across the island, with a more pronounced tendency in eastern regions. By comparing previous works with the analysis of present study through a multi-annual approach, we have been able to identify the decrease of annual rainfall volumes and events in winter since 1920s, as well as a summer increase. We have observed precipitation anomalies since 2013: we could see that, in autumn rainfall has become more frequent in the last decade, in addition the number of extreme events has grown and precipitation volumes got more extreme during this season. On the other hand, in general, differences among seasons reduced. These changes are affecting in an important way the economy of Sicily which is mainly based on agriculture, farming and touristic activities. Therefore new strategies are urgently needed for managing resources and damages, in order to reduce human and economic losses. This work represents a first empirical analysis of hourly rainfall time series in Sicily and it depicts clearly, for the first time, signal of anomalies and evidence of climate change.