| ABSTRACT | The Mediterranean area is identified as a “Hot Spot†region, vulnerable to future climate change with potentially strong impacts over the sea. By 2070-2090, climate models predict increased warming over the sea surface with possible implications on the Mediterranean thermohaline and surface circulation but also with severe impacts on the ecosystems (e.g. fish habitat loss, species extinction and migration, invasive species). Among the most important impacts is the future evolution of the extreme oceanic temperatures, which remains still an open issue of primary importance. In this context, we study here the probability and characteristics of ocean heat wave occurrence in the Mediterranean Sea in future climate projections. For this reason we developed a fully coupled regional climate system model (CNRM-RCSM4) in the framework of Med-CORDEX initiative. The atmospheric, land, river components are represented at 50 km whereas the ocean is at 9-12 km resolution respectively, without any constraint in the SST variation. After a 130-year spin up, dedicated simulations for the 20th and the 21st century are performed with respect to the different IPCC-AR5 socioeconomic scenarios (1950-2100, RCP8.5, RCP4.5, RCP2.6). In particular, spatial variability and temporal evolution of ocean heat waves are analyzed on an annual basis. Additional integrated indicators useful for marine ecosystems are also studied. The variety of factors that can cause the ocean warming (e.g. direct radiative forcing, ocean advection, stratification change) are then examined to disentangle the dominant driving force. |