Aridity and desertification in the Mediterranean under EURO-CORDEX future climate change scenarios

This study investigates future aridity changes in the Mediterranean under the RCP4.5 and RCP8.5 IPCC future climate scenarios, using nine bias-corrected, high-resolution simulations from the EURO-CORDEX project. Results show that, towards the end of the century (2081–2100 period) and under the RCP8.5 future climate scenario, precipitation and evapotranspiration are projected to strongly decrease, up to 30–40% in southern Iberian Peninsula and northwestern Africa. These changes result in slight reductions in the water balance, although these are residual, non-significant and not robust across models, except at some mountainous areas (Alps, Pyrenees and Cappadocia) where the water availability can decrease up to 40–50%. Oppositely, potential evapotranspiration is expected to strongly increase in the future due to temperature increases and reduced surface water vapour pressure deficit. These changes can reach 50% under RCP8.5 in the Alps, Pyrenees and Atlas mountain ranges. These precipitation and potential evapotranspiration changes induce a strong, significant and robust increase of aridity over the Mediterranean region, particularly at North Africa and Iberian Peninsula. However, the reductions in the AI values (i.e. increased aridity) may not always reflect a change in the aridity categories since AI categories are based on ranges of AI values and not in the AI values “per se”. These results clearly indicate that the Mediterranean is projected to become in the future more arid, due to the conjugated effects of precipitation decrease and potential evapotranspiration increase. These changes, together with growing intensive farming practices and tourism, may contribute to overexploitation of aquifers, wetland destruction and irreversible natural productivity loss, leading to irreversible water scarcity and desertification in the region.