Climate Projections of Atmospheric Parameters Historically Linked to High Summer Temperatures by 2100: The Case of the Côte D'azur

Abstract

This study analyzes projected summer climate changes (June to September) for 2100 in the Côte d'Azur (CAZ) based on atmospheric variables linked to high temperatures recorded by a network of Météo-France (MF) stations. These variables were projected using different Shared Socioeconomic Pathways (SSPs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6). Recognized as a region particularly vulnerable to climate change due to its dense and aging population, the CAZ faces increasing risks of heat-related stress. This research aims to better understand the future relationships between general atmospheric circulation and local climate changes in the study area. In the context of climate change marked by shifts in global atmospheric circulations, this study uses a multivariable classification based on four key parameters: geopotential height at 500 hPa, specific humidity at 850 hPa, the meridional wind component (V) at 850 hPa, and temperature at 850 hPa. These parameters help identify synoptic dynamics influencing local temperatures. Using historical data and SSP projections, the study evaluates the frequency and structure of atmospheric circulations projected for 2100. The results reveal that, for all time horizons and scenarios tested, the study area experiences a significant increase in the frequency of conditions favorable to very hot days, accompanied by a strengthening of anticyclonic conditions, rising temperatures, and drying of air masses at altitude. Meanwhile, very cool days become increasingly rare. These climatic changes exacerbate health risks, particularly for vulnerable populations, increasing the likelihood of heatstroke, dehydration, and premature mortality.