Heat contributed to 47,000 deaths in Europe last year, but emergency aid programs helped
A new report in Nature Medicine finds that more than 47,000 Europeans died from heat-related causes in 2023, the hottest year on record.
But the number could have been much higher.
Without adaptations to rising temperatures over the past two decades — including advances in health care, more widespread air conditioning and improved public information that kept people indoors and hydrated during extreme temperatures — the death toll for Europeans experiencing the same temperatures at the beginning of the 21st century could have been 80 percent higher, the new study finds. For people over 80, the death toll could have doubled.
“We need to look at climate change as a health problem,” said Elisa Gallo, a postdoctoral researcher at the Barcelona Institute for Global Health, a nonprofit research center, and the study’s lead author. “We still have thousands of heat-related deaths every year, so we still need to work much more and faster.”
Counting deaths from extreme heat is tricky, partly because death certificates don’t always reflect the role heat played in someone’s death. The study used publicly available death certificates in 35 countries, representing about 543 million Europeans, provided by Eurostat, the European Union’s statistical office.
The researchers used an epidemiological model to analyze the deaths in combination with weekly temperature data from 2023, allowing them to estimate what proportion of deaths could be attributed to the heat.
“We’re rapidly approaching the limits of what the human body can tolerate,” said Jordan Clark, a senior policy fellow at Duke University’s Heat Policy Innovation Hub who was not involved in the study. As the planet continues to warm, he said, “we’re running against time.”
“We can’t adapt forever,” Dr. Clark said.
Heatwaves are becoming more intense and longer lasting as global temperatures rise. Ending our dependence on fossil fuels would be a core mitigation strategy, Dr. Clark said.
The last two decades have prompted people to change their behavior in response to heat, Dr. Gallo said. Other policy-level changes, such as improving urban planning, increasing green space, investing more in renewable energy and public transportation, and reducing greenhouse gas emissions, can all contribute to adaptation.
“Adaptation has led to fewer deaths,” said Joan Ballester, an associate professor of climate and health at the Barcelona Institute and a co-author of the study. The term adaptation is meant to be very broad, he added, encompassing anything that reduces a group’s vulnerability to heat.
But pinpointing the specific adaptation measures or policies that caused the biggest differences is more difficult than estimating mortality, researchers say.
In future studies, Dr. Gallo hopes to focus more on adaptations and differences between countries. The highest rates of heat-related deaths in the study occurred in countries with the warmest temperatures for the longest period of time, including high nighttime temperatures, such as Bulgaria, Spain, Cyprus, Portugal and Italy.
“It is really important that more studies are done to evaluate what is actually being done, assessing the evolution of adaptation,” said Francesca de’Donato, an environmental epidemiologist at the Lazio Regional Health Service in Rome.
One of the first forms of adaptation in Europe was a heat-related alert system that some countries, such as Italy, adopted after an exceptionally hot summer in 2003 that caused more than 70,000 excess deaths. The country’s heat adaptation plan has been in place since 2004, based on guidelines from the World Health Organization. The system instructs medical and social service providers to check on patients most at risk every few days while an alert is issued. Patient registries identify who is more vulnerable to heat based on factors such as chronic disease, age, socioeconomic status, or whether a person lives alone.
A new website called Health Predictorcreated by the Barcelona Institute, provides an alert system that isolates subgroups that are most vulnerable in terms of gender and age. In the future, Dr. Gallo said, those alerts could be even more specific for different diseases such as heart disease.
Dr. de’Donato’s region of Italy has been experiencing a heatwave since late June. She said prolonged heatwaves like this, where temperatures do not drop significantly for several days in a row, can have the greatest impact on human health.
Ashley Ward, director of Duke University’s Heat Policy Innovation Hub, said the timing of the study is critical, as it comes shortly after a Global call for action on extreme heat issued last month by the Secretary-General of the United Nations.
“Europe is really ahead of the U.S. in a lot of these activities, like heat management and early warning systems,” said Dr. Ward. “The problem is growing faster than the data is improving.”
