The Lethal Grip of Heat: Mapping the Heat Wave-Mortality Nexus in Spain (1975-2019)

Dariya Ordanovich, IEGD-CCHS Spanish National Research Council (CSIC)
Ana Casanueva, University of Cantabria
Aurelio Tobias, Institute of Environmental Assessment and Water Research, Spanish Council for Scientific Research
Diego Ramiro , Consejo Superior de Investigaciones Científicas (CSIC)

Nowadays, the rise in the global temperatures are a source of apprehension, particularly in the Mediterranean region, where Spain is witnessing notable consequences for its population. Predictions for the end of the XXI century reveal a persistent increase in air temperatures along with an increment of extreme episodes. Abnormal heat, once considered an ’environmental accident’, is now a serious public unease. The study aims to measure the impact of heat waves on mortality by age and sex over 45 years across Spanish provinces. Here we leverage daily individual mortality data from the National Institute of Statistics and air temperature estimates from the ERA5 global reanalysis. We also use the historical settlement data as a proxy for population distribution from 1975 onward. To estimate the main and added effects of heat waves we fit a quasi-Poisson time-series regression model using a distributed lag non-linear model with 10 days of lag, controlling for trends and day of the week. This analysis examines 15.8 million deaths in Spain from 1975 to 2019. Over this period, we anticipate a shift in the temperature-mortality relationship, indicating a gradual flattening of the response curve and overall reduction in temperature-related mortality. We expect a more pronounced decrease in cold-related risks compared to heat-related ones, with latitudinal variations. Heat wave incidence is steadily increasing, with a positive effect on mortality, albeit smaller than the primary temperature effect. This heat wave effect is expected to vary as function of the heat wave type, location and demographic strata.

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 Presented in Session P92. Climate Change, Morbidity and Mortality