High temperatures rarely bring anything good. They can lead to extreme weather events , such as an increase in hurricanes due to warmer waters, more severe droughts, and worsened wildfires. However, there is also a significant link between high temperatures and mortality rates , which requires urgent attention, especially in a world facing climate change. For more information on the impacts of these phenomena, you can consult the article on the impacts of heat waves.
Everyone faces risks. Outdoor activities and work are particularly dangerous during heat waves. A tragic example is the case of a 54-year-old man who died two weeks ago due to the heat wave while working on asphalt paving in Morón de la Frontera. However, there is a group of people who, regardless of their work, are more susceptible to the effects of high temperatures.
Who and how does it affect?
On a physical level, high temperatures particularly affect the elderly, as well as those with cardiovascular or respiratory conditions, or diabetes. It has been proven that not only is exposure to high temperatures deadly, but also the duration of that exposure. Data shows that on a day with high temperatures, the percentage of deaths rises by 4% compared to the estimated average . If these temperatures persist for two days, deaths increase to 10% the following day, and to 22% by the third day. The risk is even greater in children under one year old, where deaths rise to 25%, and doubles if they also suffer from respiratory, digestive, or cardiovascular conditions.
On a psychological level , there are also devastating effects, with studies finding a link between suicide rates and heat waves. Looking at historical records, we have the major heat wave in Europe in 2003, which resulted in an estimated 35,000 additional deaths. To explore these effects further, you can read about how climate change is raising temperatures.
It is essential to remember the importance of protecting yourself from the heat when temperatures rise. Staying hydrated and avoiding physical activity during the hottest hours is crucial, especially for vulnerable groups, but also for the general population. The effects on our bodies are proportionally more harmful as temperatures increase.
Recent data on heat-related mortality
According to recent studies, more than 47,000 people died in Europe as a result of high temperatures in 2023, which is considered the warmest year on record globally and the second warmest in Europe. This information was published in Nature Medicine by a team led by the Barcelona Institute for Global Health (ISGlobal). They estimate that, without the adaptation processes that societies have developed over time, the heat-related mortality burden last year would have been 80% higher.
The study used temperature and mortality records from 823 regions in 35 European countries between 2015 and 2019 to employ epidemiological models that estimated heat-related mortality in 2023. Although the summer of 2022 was characterized by persistent extreme temperatures, 2023 did not see major temperature anomalies, but two high-temperature episodes in July and August were responsible for more than 57% of the estimated global mortality, with over 27,000 deaths. For a more in-depth analysis of climate change and its impact, you can read about heat waves.
Southern European countries are the most affected
The analysis yielded an estimated total of 47,690 deaths in 2023 across the 35 countries studied , of which 47,312 occurred during the hottest period of the year, from May 29 to October 1. When considering population, the countries most affected in terms of heat-related mortality rates are located in Southern Europe , specifically Greece (393 deaths per million), Bulgaria (229 deaths per million), Italy (209 deaths per million), Spain (175 deaths per million), Cyprus (167 deaths per million), and Portugal (136 deaths per million). Furthermore, it is important to note that Spain is the country most affected by heat waves in all of Europe.
Greater vulnerability of women and people over 80 years of age
According to previous studies, the data shows greater vulnerability in women and older people. Specifically, when considering the general population, the heat-related mortality rate was 55% higher in women than in men and a staggering 768% higher in people over 80 years old compared to those between 65 and 79 years old. For more information on these demographic phenomena, it is worth consulting the article on population exposure to heat waves.
Possible underestimation of the true burden of heat-related mortality
The study also cautioned that these figures may underestimate the true burden of heat-related mortality. Due to the lack of consistent daily records throughout 2023, the team used weekly counts from Eurostat, which could contribute to this underestimation. Thus, the likely number of heat-related deaths in 2023 is estimated to have been approximately 58,000 across the 35 countries studied . This underscores the need for more rigorous monitoring of heat-related mortality.
Social adaptation to heat prevents up to 80% of mortality
One of the study's goals was to assess whether there has been a decrease in heat vulnerability in Europe, which is generally understood as an adaptation to rising temperatures. To do this, the team analyzed temperature and mortality data from previous periods (2000–2004, 2005–2009, 2010–2014, and 2015–2019). By inserting the 2023 figures into these models, they calculated that if the temperatures recorded in 2023 had occurred during the 2000–2004 period, the estimated heat-related mortality would have exceeded 85,000 deaths — 80% higher than the heat vulnerability in 2015–2019. This highlights the importance of implementing effective policies, such as those discussed in the article on the urban heat island effect and its cost.
On the other hand, deaths in people over 80 years of age have more than doubled, going from 1,102 to more than 2,200 heat-related deaths, thus demonstrating that there has been a substantial social adaptation to heat waves.
As highlighted by Elisa Gallo , ISGlobal researcher and lead author of the study, “our results show how there have been processes of adaptation of society to high temperatures during the present century, which have drastically reduced vulnerability to heat and the mortality burden of recent summers, especially among the elderly.”
Beyond the physiological limits of adaptation
Professor Joan Ballester Claramunt , principal investigator of the European Research Council (ERC) Consolidator EARLY-ADAPT grant, stated that “in 2023, almost half the days exceeded the 1.5°C threshold stipulated by the Paris Agreement, and Europe is warming at twice the rate of the global average. This limit is likely to be exceeded before 2027, leaving us with a very small window of opportunity to act.”
It is urgent to implement strategies to reduce the burden of mortality during the warmer summers ahead and to provide detailed monitoring of the effects of climate change on vulnerable populations. These adaptation measures must be combined with mitigation efforts by governments and the general public to avoid reaching tipping points and critical thresholds in temperature projections.
Forecaster.health, a tool for predicting mortality risk by sex and age
A new web tool, Forecaster.health , has been launched by the research group responsible for the study. This platform provides predictions of mortality risks associated with cold and heat, broken down by sex and age. The tool uses epidemiological models to estimate actual health risks in 580 regions across 31 European countries. It is available free of charge ( https://forecaster.health/ ) and offers forecasts up to 15 days in advance. This tool has the potential to be crucial in preventing heat-related deaths.
The EARLY-ADAPT Project
The study is part of the EARLY-ADAPT project , funded by the European Research Council, which aims to investigate how populations are adapting to the public health challenges posed by climate change.
Heat-related mortality in Spain
A team of scientists from the Institute of Environmental Assessment and Water Research (IDAEA-CSIC) and the University of Valencia have developed an application called Heat-Attributable Mortality in Spain (MACE) . This tool uses data from the Daily Mortality Monitoring System (MOMO) and temperatures recorded by the State Meteorological Agency (AEMET) to calculate mortality attributable to moderate, extreme, and excessive heat from June to August.
The year 2022 proved significant, with 3,012 heat-related deaths recorded during 28 days of extreme heat. “During the summer of 2023, the third deadliest summer on record for heat-related mortality, 2,155 deaths were reported, following the heat waves of 2003 and 2022,” explained Aurelio Tobías , a researcher at IDAEA and author of the study. This highlights the growing concern about the effects of extreme heat on public health, as well as the fact that temperature records in Spain have reached alarming levels. For more details on the situation in Spain, it is advisable to consult the article analyzing global warming in Spain.
The MACE database is updated daily and allows users to calculate mortality based on data from the last five years. This application not only facilitates data visualization but also promotes a change in public behavior by highlighting the impact of extreme heat on health.
Researchers emphasize that heat waves are one of the most evident effects of climate change, and the number of deaths attributed to them has increased in recent years. It is estimated that more than 153,000 additional deaths occurred globally between 1990 and 2019 due to heat waves. With the growing impact of climate change, an increase has been observed not only in the frequency but also in the severity of these phenomena. A recent report warns that without urgent action to mitigate climate change, there could be more than 2.3 million temperature-related deaths in Europe by the end of the century, highlighting the need for effective mitigation and adaptation policies.
