Research shows that heat will cause more than 47,000 deaths in Europe by 2023, the second highest burden in the past decade

More than 47,000 people died in Europe as a result of high temperatures in 2023, the hottest year on record worldwide and the second warmest year in Europe. This is the estimate of a study led by the Barcelona Institute for Global Health (ISGlobal). published in Naturopathy.

The researchers report that the vulnerability of European societies to heat has gradually decreased over the past century, and estimate that without these social adaptation processes, the heat-related mortality burden would have been 80% higher over the past year.

The study replicates the methodology used in another paper published last year Naturopathywhich estimated that heat caused more than 60,000 deaths in the summer of 2022, representing the highest heat-related mortality burden in the past decade.

In a nutshell, researchers used temperature and mortality data from 823 regions in 35 European countries for the period 2015-2019 to fit epidemiological models to estimate heat-related mortality in each European region over the entire year 2023.

In contrast to the summer of 2022, which was characterized by persistent extreme temperatures in the central part of the season from mid-July to mid-August, no major thermal anomalies were recorded in the same weeks in 2023. The temperatures of mid-July and late August would have been responsible for more than 57% of the total estimated mortality, with more than 27,000 deaths.

Southern European countries are the hardest hit

The results show a total of 47,690 estimated deaths in 2023 in the 35 countries as a whole, of which 47,312 deaths would have occurred in the hottest period of the year (between May 29 and October 1).

When population is included, the countries with the highest heat-related death rates were in Southern Europe, namely Greece (393 deaths per million), Bulgaria (229 deaths per million), Italy (209 deaths per million), Spain (175 deaths per million). million), Spain (175 deaths per million), million), Cyprus (167 deaths per million) and Portugal (136 deaths per million).

This link shows the details of the mortality estimates for the 35 countries analyzed.

Higher vulnerability for women and people over 80 years of age

In line with previous studies, the data show greater vulnerability among women and the elderly. Specifically, after taking into account population, the heat-related death rate was 55% higher in women than in men, and 768% higher in people over 80 years of age than in people between 65 and 79 years of age.

Possible underestimation of the actual heat-related mortality burden

The study authors warn that these figures may underestimate the true heat-related mortality burden. Because no daily, homogeneous mortality data were available during the year 2023, they had to use weekly death counts from Eurostat.

In a recent one study published in the Lancet Regional Health – Europethe same authors showed that using weekly data would lead to an underestimate of the heat-related mortality burden, and described a methodology to correct this bias.

Taking this into account, researchers estimate that the likely death toll from heat in 2023 could actually have been on the order of 58,000 deaths in the 35 countries studied, although a more accurate estimate could only be obtained if improved mortality databases were made available to the population. scientific community.

Social adaptation to heat prevents up to 80% of mortality

One of the objectives of the study was to assess whether Europe is experiencing a decline in vulnerability to heat, a process widely understood as an adaptation to rising temperatures.

To do this, the researchers applied the same type of model to temperature and mortality data from the periods 2000–2004, 2005–2009, 2010–2014 and 2015–2019. They then plugged the 2023 temperatures and death rates into each of the four models to estimate the number of deaths that would have occurred in each period if temperatures had been as high as in 2023.

Using this method, it was estimated that if the temperatures recorded in 2023 had occurred in the period 2000-2004, the estimated heat-related mortality would have exceeded 85,000 deaths, i.e. 80% higher than the result resulting from the vulnerability. to be heated in the period 2015-2019. For people over 80 years old, the number of deaths would have more than doubled, from 1,102 to more than 2,200 heat-related deaths.

“Our results show how social adaptation processes to high temperatures have taken place over the past century, dramatically reducing the heat-related vulnerability and mortality burden of recent summers, especially among the elderly,” said Elisa Gallo, researcher at ISGlobal and lead researcher. author of the study.

‘For example, we see that the minimum mortality temperature – the optimal temperature with the lowest mortality risk – has gradually warmed on average across the continent since 2000, from 15ºC in 2000–2004 to 17.7ºC in 2015–2019.

“This indicates that we are less vulnerable to heat than at the beginning of this century, likely due to overall socio-economic progress, improvements in individual behavior and public health measures such as the heat prevention plans implemented after the record disaster. breaking the summer of 2003.”

Beyond the physiological limits of adaptation

“In 2023, almost half of days exceeded the 1.5°C threshold set by the Paris Agreement, and Europe is warming at a rate twice as fast as the global average. Climate projections indicate that the 1.5°C limit is likely to be exceeded sooner. 2027, which gives us a very small window of opportunity to take action,” said Joan Ballester Claramunt, principal investigator of the European Research Council (ERC) Consolidator Grant. EARLY ADJUSTMENT.

“We must take into account that inherent limits in human physiology and social structure are likely to place a limit on the potential for further adaptation in the future,” he adds.

“There is an urgent need to implement strategies aimed at further reducing the mortality burden of the coming warmer summers, along with more extensive monitoring of the impacts of climate change on vulnerable populations. These adaptation measures must be combined with mitigation efforts by governments and the general population to avoid reaching tipping points and critical thresholds in temperature projections.”

A tool for predicting mortality risk by gender and age

The research group that conducted the study recently presented Predictor.healtha publicly accessible web-based tool that provides predictions of mortality risk associated with cold and heat, broken down by gender and age for 580 regions in 31 European countries.

This early warning system is not based solely on meteorological data, but includes epidemiological models to estimate the real health risks for each population group. Forecaster.health is available for free and provides forecasts up to 15 days in advance.