Change in Aridity Index in the Mediterranean Region under Different Emission Scenarios

In the present study, the spatial and temporal variability of the Aridity Index (AI) in the Mediterranean region during the 30-year period 1971–2000 is analyzed. The analysis is performed on a decadal timescale. Subsequently, the projected change in the AI in the periods 2031–2060 (near future) and 2071–2100 (far future) under the RCP4.5 and RCP8.5 emission scenarios in comparison with 1971–2000 (reference period) is presented. The input of the calculations are simulation results supplied by the CORDEX EU project. In total, an ensemble of 20 combinations of global climate models (GCMs) and regional climate models (RCMs) are used. The calculation of the AI is based on potential evapotranspiration, which, in turn, is calculated according to the classic method of Thornthwaite. Our results show that drier conditions are to be expected in the future along a wide zone in southern Europe, including Spain, Italy, Bulgaria, Greece and Turkey, as well as in Northern Africa, particularly under the RCP8.5 scenario and towards the end of the century.