European heat-related deaths exceed 62,000 in 2024, highlighting regional vulnerability

The year 2024 broke several temperature records: it was the hottest ever recorded, and its summer was also the warmest to date. A study led by the Barcelona Institute for Global Health (ISGlobal), a center supported by the "la Caixa" Foundation, has estimated that 62,775 heat-related deaths occurred in Europe between 1 June and 30 September of that year. These mortality figures are 23.6% higher than the approximately 50,800 estimated for the summer of 2023, and 8.1% lower than the nearly 67,900 estimated for the summer of 2022. These results have been published in Nature Medicine.

Italy and Spain, the countries with the highest number of deaths

The study focused on 654 regions in 32 European countries. The country with the highest number of heat-related deaths was Italy, with more than 19,000 estimated deaths in the summer of 2024. In the previous summers of 2023 and 2022, Italy was also the country with the highest heat-related mortality, with an estimated 13,800 and 18,800 deaths, respectively.

The country with the second highest estimated mortality in the summer of 2024 was Spain, with more than 6,700 deaths, followed by Germany (around 6,300), Greece (around 6,000) and Romania (more than 4,900). In the case of Spain, estimated deaths in 2024 were almost half those for 2022, due to lower summer temperatures than in the previous two years. In the case of Spain, estimated deaths in 2024 were almost half those for 2022, due to lower summer temperatures than in the previous two years.

Top 10 European countries with the highest estimated number of deaths

Greece and Bulgaria, countries with the highest mortality rates

In terms of mortality incidence, the countries with the highest heat-related death rates for the same period were Greece (574 estimated deaths per million people), Bulgaria (530 deaths per million) and Serbia (379 deaths per million). These rates were significantly higher than those estimated for the two previous summers of the study, the highest of which was 373 deaths per million in Greece during 2023.

Overall, 15 of the 32 assessed countries experienced their highest heat-related mortality burden and rates during the summer of 2024.

Top 10 European countries with the highest estimated heat-related mortality rates

Differences by sex and age

The number of heat-related deaths was higher among women and older people during the three summers studied (2022, 2023 and 2024). Specifically, it is estimated that in the summer of 2024, the number of heat-related deaths among women was 46.7% higher than among men. In people over 75, the estimated mortality rate was 323% higher than in all other age groups.

Most vulnerable regions

"Although the summer of 2024 was the hottest on record according to Copernicus, in the specific regions of our study, the summers of 2022 and 2023 were actually hotter. However, these regional differences in average temperature are not fully reflected in mortality, as the estimated deaths for 2024 were higher than those estimated for the summer of 2023 and only slightly lower than those for 2022. This is because in 2022 and 2024, the highest temperatures occurred in south-western and south-eastern Europe, respectively, both areas that are highly vulnerable to heat," explains Tomáš Janoš, ISGlobal and Recetox researcher and first author of the study.

Europe is the continent that is warming most quickly, at twice the global average. And within Europe, the Mediterranean basin and south-eastern regions are emerging as major climate change hotspots, facing the greatest impacts on health and with a substantial rise in heat-related mortality projected during the 21st century."

Tomáš Janoš, Researcher, ISGlobal

Forecaster. Health, an effective and reliable tool for emergency heat alerts

In total, the study suggests that there were more than 181,000 heat-related deaths in Europe during the three summers studied, two-thirds of which occurred in southern Europe. According to Joan Ballester Claramunt, principal investigator of the European Research Council (ERC) EARLY-ADAPT project, and senior author of the study, the magnitude of these figures highlights the need to "strengthen adaptation strategies, including the development and implementation of a new generation of continent-wide, impact-based heat-health early warning systems".

For this reason, part of the study was devoted to evaluating Forecaster.health, a tool created within the ERC Proof-of-Concept Grants HHS-EWS and FORECAST-AIR, which uses epidemiological models to transform weather forecasts into daily operational heat-health alerts by region and for specific population groups. The analysis shows that the tool is highly reliable in issuing heat-health alerts at least one week in advance when conditions point to an exceptional mortality risk.

"In southern Europe, however, the early warning system continued to show relatively high reliability even beyond this seven-day horizon, which considering that this is the area with the highest heat-related mortality on the continent, represents an unexplored opportunity to save lives among the most vulnerable populations", says Joan Ballester Claramunt.

Methodology

The team used daily regional temperature observations and mortality records for the period 2015-2019 to fit the epidemiological models. Once fitted, these were combined with daily temperature observations and forecasts and with weekly mortality series for the years 2022 to 2024 to calculate heat-related mortality in these three recent summers.

Re-estimation of heat-related mortality in the summers of 2023 and 2022

This study follows on from previous studies on estimated mortality for the summers of 2023 and 2022, respectively. After finding that the use of weekly mortality records to fit epidemiological models led to an underestimation of heat-related mortality of between 5% and 20%, the team this time used daily mortality series from the database of the EARLY-ADAPT project (www.early-adapt.eu) to fit the epidemiological models.

Using this improved methodology, the data for the summers of 2022 and 2023 were reprocessed, resulting in higher mortality estimates than in previous years' studies, which the researchers consider to be more accurate.