Direct Impacts of Climate Change on Mortality in France

Climate change has major implications for population health. In France, the 2003 heatwave caused nearly 15,000 deaths, and similar events are expected to become more frequent and severe in the coming decades. This study assesses the direct impact of climate change on mortality in metropolitan France. We combine open-source data from INSEE (individual death records since 1990, including date and municipality) and Météo-France (daily mean temperatures across thousands of points nationwide), together with INSEE’s historical population estimates. These sources allow daily estimates of mortality risk accounting for local temperature exposure. Extensive preprocessing of the INSEE death records was required to identify and correct anomalies and ensure consistency with national population estimates. On these validated data, we first reveal a significant temperature effect on mortality by examining residuals from models excluding temperature. Using generalized additive mixed models (GAMMs), we then incorporate temperature as a covariate. This approach captures non-linear effects while limiting overfitting, crucial when dealing with numerous explanatory variables and rare temperature extremes. Finally, combining INSEE population projections with IPCC climate scenarios, we estimate the expected direct impacts of future climate change on mortality across France.