The study found that heatwaves caused by carbon pollution killed around 50,000 people in Europe last year and that the continent is warming much faster than the rest of the world.
The findings come as wildfires rage in forests outside Athens, France issues heat alerts for much of the country and Britain experiences what the Met Office predicts will be its hottest day of the year.
Doctors call heat a “silent killer” because it claims far more lives than most people realize: A study published in Nature found that if people hadn't adapted to rising temperatures over the past 20 years, the catastrophic death rate in 2023 would have been 80% higher.
Elisa Gallo, an environmental epidemiologist at ISGlobal and lead author of the study, said the results showed efforts to adapt society to heatwaves were effective.
“But the number of deaths from heatstroke remains too high,” she warned. “With Europe warming twice as fast as the global average, we cannot afford to be complacent.”
As humans burn fossil fuels and damage nature, heatwaves have become hotter, last longer, and occur more frequently. Greenhouse gases are building up in the atmosphere and heating up the planet. Globally, 2023 will be the hottest year on record, and scientists expect 2024 to soon surpass that record.
The researchers say cooler European countries, such as Britain, Norway and Switzerland, will see the greatest relative increase in uncomfortably hot days, but the absolute number of deaths will remain highest in southern Europe, which is adapted to hot climates but still more exposed to scorching temperatures.
The scientists found that Greece had the highest heatstroke death rate in 2023 at 393 deaths per million people, followed by Italy with 209 and Spain with 175.
Greek firefighters battled a wildfire on the outskirts of Athens on Monday that forced authorities to evacuate several suburbs of the capital and a children's hospital as repeated heat waves dried out the surrounding forest, turning trees to tinder.
In 2003, a heatwave killed 70,000 people across the continent, sending authorities scrambling to develop early warning systems and prevention plans to save lives. But nearly two decades later, a record-breaking heatwave in 2022 has killed more than 60,000 people, leaving researchers questioning how effective those measures were.
Scientists modeled the health impacts of heat at different times this century and estimated the death toll at 47,690 last year. If the temperatures in 2023 had occurred between 2000 and 2004 rather than the pre-pandemic reference period of 2015 to 2019, the death toll would have been 80% higher, the researchers found. For people over 80 years old, heat would have been twice as deadly.
Dominique Royer, head of data science at the Climate Research Foundation, who was not involved in the study, said the results are in line with published research. Royer added that there is a need to better monitor the effects of heat on the most at-risk groups and implement plans to prevent deaths.
People use the fountains and sprinklers to cool off before watching the Paris 2024 Olympic Games. Photo: Tolga Akmén/EPA
“We monitor temperature very well, but not in the same way its health effects,” Royer said. “Society adaptation to rising temperatures has played an important role in preventing mortality in Europe, but it is not yet enough.”
Scientists say governments can protect people from heatwaves by designing cooler cities with more parks and less concrete, installing early warning systems to alert people to impending danger, and strengthening health-care systems so doctors and nurses don't have to be overworked when temperatures soar.
But individual actions like staying indoors and drinking water also have a big impact on the death toll, and checking in on elderly neighbours or relatives who live alone could mean the difference between life and death.
Dr. Santi Di Pietro, an assistant professor of emergency medicine at the University of Pavia, said his colleagues are treating more patients per day than they were in early January during flu season.
He said heatwaves needed to be tackled at all levels, but people could take “simple steps” to protect themselves and their loved ones, including staying out of the sun during the hottest parts of the day, seeking shade when outside and drinking water instead of alcohol.
“It may sound obvious, but drinking water is the most important thing to do to prevent dehydration,” he says, “especially for older adults, who often don't feel thirsty.”
More work is needed to adapt to climate change and mitigate rising temperatures, Gallo said. “Climate change needs to be considered as a health issue.”
