  Most contemporary mortality models rely on extrapolating trends or past
events. However, population dynamics will be significantly impacted by climate
change, notably the influence of temperatures on mortality. In this paper, we
introduce a novel approach to incorporate temperature effects on projected
mortality using a multi-population mortality model. This method combines a
stochastic mortality model with a climate epidemiology model, predicting
mortality variations due to daily temperature fluctuations, be it excesses or
insufficiencies. The significance of this approach lies in its ability to
disrupt mortality projections by utilizing temperature forecasts from climate
models and to assess the impact of this unaccounted risk factor in conventional
mortality models. We illustrate this proposed mortality model using French data
stratified by gender, focusing on past temperatures and mortality. Utilizing
climate model predictions across various IPCC scenarios, we investigate gains
and loss in life expectancy linked to temperatures and the additional mortality
induced by extreme heatwaves, and quantify them by assessing this new risk
factor in prediction intervals. Furthermore, we analyze the geographical
differences across the Metropolitan France.
