Mediterranean climate change projections from CMIP5 and CMIP6

Abstract

The Mediterranean has been identified as a climate change hotspot due to increased warming trends and precipitation decline. To estimate the impacts of the ongoing climate change on the region, projections of various CMIP5 and CMIP6 experiments and scenarios are compared. The changes in temperature and precipitation for the 21st century are studied under scenarios RCP2.6/SSP1-2.6, RCP4.5/SSP2-4.5 and RCP8.5/SSP5-8.5 as well as the high resolution High-ResMIP experiments. Additionally, to give robust estimates of projected changes a model weighting scheme is applied, accounting for historical performance and inter-independence of the multi-member multi-model ensembles. Results indicate a significant and robust warming over the Mediterranean during the 21st century over all the ensembles and experiments. Nevertheless, the amplified Mediterranean warming with respect to the global average is only found for summer. Projected changes vary between CMIP5 and CMIP6, with the latter projecting a stronger warming. In contrast to temperature, precipitation changes show a higher level of uncertainty and spatial heterogeneity. However, for the high emission scenario, a robust decline in precipitation is projected for large parts of the region during summer. Results applying the model weighting scheme indicate reductions in CMIP6 and increases in CMIP5 warming trends, making the differences between the two ensembles smaller