Searing heat killed more than 60,000 people in Europe last summer, scientists have found, in a disaster made deadlier by greenhouse gases baking the planet.
EU statisticians rang alarm bells in August, as sweltering heat, withering drought and raging fires consumed much of the continent, after seeing unusually high numbers of people die during Europe’s hottest summer on record.
Public health experts took that data and used epidemiological models to work out how many deaths could be traced back to the temperature. They found 61,672 people died of heat-related causes in Europe between 30 May and 4 September 2022. The mortality rate was highest in Italy, Greece, Spain and Portugal.
“There are people that would have died anyway, but those are not counted with this methodology,” said Joan Ballester, an associate research professor in climate and health at Barcelona Institute for Global Health and lead author of the study. “We are talking about people for whom the occurrence of these temperatures triggered their death.”
Only a small share of heat-related deaths come from heatstroke. In most cases, hot weather kills people by stopping the body from coping with existing health problems like heart and lung disease.
In every week of summer 2022, the study found, average temperatures in Europe “uninterruptedly” exceeded the baseline values of the previous three decades. The most intense heat hit from 18 to 24 July, when it killed 11,637 people.
Among the people who died that week was an 86-year-old woman called Maria, who lived alone with no air-conditioning, said Ángel Abad, a doctor at La Paz university hospital in Madrid who was not involved in the study. She took diabetes and heart medication every day but came into the hospital on 19 July complaining of tiredness, he said. She died five days later from acute pulmonary oedema.
“It’s very frequent in summer in Spain in our hospitals,” said Abad, adding that patients grow anxious as they become aware they are dying. “The patient cannot breathe. The heart starts failing. The [underlying] problem becomes stronger.”
Humans have heated the planet by about 1.1C but in Europe temperatures have risen nearly twice as fast as the global average. Unless governments protect people from hotter weather and spew fewer planet-heating gases, heatwaves will become even deadlier.
The scientists suggested the death toll in 2022 was particularly high because the temperature anomalies – the gaps between heat felt today and in the past – were greatest in southern Europe, which is hotter than northern Europe, and during the peak of summer, when days are hottest and nights offer little respite.
“We had both factors contributing to the mortality,” said Ballester. “In the end it’s the absolute temperature that kills.”
Ana Maria Vicedo-Cabrera, the head of the climate and health research group at the University of Berne, who was not involved in the study, praised the analysis but said the true death toll may be even higher.
The researchers used weekly data on temperature and mortality that diluted the effects of short-term spikes, she said. One study that used daily data for Spain estimated 10% more heat-related deaths for the country than the weekly data suggested. A separate study by Vicedo-Cabrera and colleagues, published on Tuesday, showed an even bigger effect in Switzerland, where the estimate from daily data was double that of the estimate from weekly data.
Both the Swiss and Europe-wide studies found that women, and particularly older women, died at higher rates than men. Pollution from burning fossil fuels and destroying nature upped the death toll, the Swiss research also showed. “We found 60% of the observed deaths can be attributed to climate change,” said Vicedo-Cabrera.
More than 2,000 senior women in Switzerland have taken the federal government to the European court of human rights for failing to do enough to stop global warming – citing the risk to their own health from heatwaves. The Swiss government has argued the link between its actions and their suffering was “too tenuous and remote”.
Strengthening healthcare systems and protecting vulnerable groups would save lives, said Julie Arrighi, acting director of the Red Cross Red Crescent climate centre. “It’s so crucial for people to look out for neighbours and loved ones – especially those living alone.”
