Heat-related mortality projections for 335 European NUTs3 regions

Under climate change, heat waves are expected to become more frequent, more intense, and longer representing a risk factor in mortality and morbidity and a significant threat to public health [1]. In this study, we have performed a mortality impact assessment due to heat in European regions estimating the number of deaths related to mortality in each European country.

Our dataset includes the relative risk of death related to high-temperature data, as well as baseline mortality (2013) and projections (2030, 2050, and 2070) for adults over 65 years. We have calculated the number of deaths attributed to heat using the World Health Organization (WHO) relative risk model [2]. Adaptation was partly incorporated into the assessment by adjusting the optimum temperature in future periods under 4 combinations of climate and socioeconomic scenarios (RCP2.6-SSP1, RCP4.5-SSP2, RCP7.0-SSP3 and RCP8.5-SSP5) based on the latest CMIP6 data.

Preliminary results show that heat-related risk and the number of deaths increase with time, as expected. In the short term (2030), the increase in mortality measured as the ratio between projected and baseline mortality, does not change much across scenarios. The average rate of daily deaths for the EU27 is 2.054 (1.766,2.354) under SSP1-2.6 (the central estimate is the median, and percentiles 10 and 90 have been used for the interval), and 2.244 (1.853,2.694) in SSP5-8.5. Mortality increases over time, although it varies greatly depending on the scenario considered. By 2070 the number of fatalities reach 3.529 (2.849,4.88) in SSP1-2.6 and 7.658 (5.984,10.07) in SSP5-8.5. We also find significant differences across countries. By 2070, under a middle-row scenario (SSP2-4.5), countries such as Belgium, Bulgaria, Czechia, Denmark, Germany, Estonia, Croatia, Latvia, Lithuania, Finland, and Sweden present an increase in mortality between 2 and 3 fold baseline mortality. Others, mostly in Southern Europe such as Greece, France, Malta, Italy or Cyprus, but also Luxemburg and Slovenia, have a severe increase in mortality, 5 to 9 times baseline mortality.

We also estimated the annual number of deaths in the EU27 due to extreme heat. In the baseline, our results are 72,955 annual deaths, which exceeds previous estimates, such as that obtained for the summer of 2022 [6], but this difference could be linked to the use of more recent CMIP6 data. In 2070, the number of heat-induced deaths in the EU could reach 211.039 (140.686,293.409) in SSP1-2.6 and 435.331 (283.927,671.089) in SSP5-8.5. Some studies [3] show that, under RCP8.5, annual mortality will possibly increase by up to 300,000 excess deaths by the last quarter of the 21st century, accounting for exposures above the minimum mortality temperature, including extremely hot temperatures, so our figures do not differ much of these estimates, even though they are higher than some others [4, 5].