Future droughts in northern Italy: high resolution projections using EURO-CORDEX and MED-CORDEX ensembles

Abstract

We analyse the expected characteristics of drought events in northern Italy for baseline (1971–2000), near (2021–2050) and far (2071–2100) future conditions, estimating the drought spatial extent and duration, the percentage of affected area and the frequency of drought episodes. To this end, daily ensembles of precipitation and temperature records from Global Climate Models (GCMs) and Regional Climate Models (RCMs) pairs, extracted from EURO-CORDEX and MED-CORDEX for the RCP 4.5 and 8.5 scenarios, were collected at spatial resolution of 0.11 degrees. Before the analysis, model outputs were validated on daily weather station time series, and scaling factors for possible use in bias correction were identified. Annual temperature and precipitation anomalies for near and far future conditions were investigated; drought events were identified by the Standardized Precipitation Evapotranspiration Index and Standardized Precipitation Index at the 12-, 24- and 36-month time scales. This study highlights the importance of using multiple drought indicators in the detection of drought events, since the comparison revealed that evapotranspiration anomaly is the main triggering factor. For both scenarios, the results indicated an intensification of droughts in northern Italy for the period 2071–2100, with the Alpine chain being especially affected by an increase of drought severity. A North-to-South spatial gradient of drought duration was also observed.