Study of climate-related heat risks to public health in the Mediterranean region.

Climate change poses severe threats to human populations worldwide, with particularly strong impacts on health. Extreme events are becoming more frequent, intense, and prolonged as a consequence of global warming. Among these, heat waves represent one of the most direct manifestations, with significant health implications. This thesis focuses on the Mediterranean basin, identified as a ’climate change hotspot’ due to its warming rates higher than other zones, and high population density. An ensemble of nine climate models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) was employed to assess future temperature trends under two Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5) and three time horizons (short: 2021-2040, medium: 2041-2060, long: 2081-2100), and compared with the historical baseline (1981-2010). Daily maximum near surface air temperature (tasmax) was chosen as indicator of heat waves. Future temperature distributions were combined with a Relative Risk (RR) function to estimate excess mortality, defined as the percentage increase relative to baseline mortality. Hazard was determined from deviations above the Optimum Temperature (Topt), vulnerability with the RR function, while exposure was considered through population data, since climate risk assessment derives from interactions among these three factors. Ensemble mean and uncertainty among models were determined, showing higher uncertainty values along coastlines. In addition, some cities were analyzed, selected for their different locations, climatic conditions and population. The results confirm an increase in mortality due to heat, reaching values of 3% with respect to baseline mortality, under the SSP5-8.5 long-term scenario. Areas at higher risk were identified through a synthetic index, which allows the combination of future population exposure and future excess mortality. This analysis adopts a method already used in the literature, though not previously applied to such extended regions, providing insights into the health implications of global warming in one of the world’s most vulnerable regions and offering a framework that could be developed in future studies.