Rising heat driven by climate change caused an estimated 16,500 deaths in European cities this summer, researchers said Wednesday.
The study, led by scientists from Imperial College London and the London School of Hygiene and Tropical Medicine, used climate modelling to estimate the impact of global warming between June and August.
They analysed 854 cities, representing almost one-third of Europe’s population. Global warming made average temperatures 2.2C hotter, the team found.
Based on historical data about how extreme heat drives up mortality, they estimated around 24,400 excess deaths during the three-month period. Nearly 70 percent of those – about 16,500 – were attributed to human-caused climate change.
“The causal chain from fossil fuel burning to rising heat and increased mortality is undeniable,” said Friederike Otto, a climate scientist at Imperial College London who co-authored the study.
“If we had not continued to burn fossil fuels over the last decades, most of the estimated 24,400 people in Europe wouldn’t have died this summer.”
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Older people most at risk
More than 85 percent of the estimated deaths were among people aged 65 and older.
Rome recorded the highest toll with 835 deaths linked to climate change, followed by Athens with 630 and Paris with 409.
“An increase in heatwave temperature of just 2C to 4C can be the difference between life and death for thousands of people – this is why heatwaves are known as silent killers,” said study co-author Garyfallos Konstantinoudis.
Most deaths happened indoors, where vulnerable people struggled with underlying health conditions.
“The vast majority of heat deaths happen in homes and hospitals, where people with existing health conditions are pushed to their limits,” Konstantinoudis said. “But heat is rarely mentioned on death certificates.”
Some victims who died outdoors were identified by local media. In Spain, 77-year-old former councillor Manuel Ariza Serrano collapsed and died during a walk in the Córdoba region in August, when temperatures hit 45C.
In northern Italy, 47-year-old father of four Brahim Ait El Hajjam died while laying concrete near Bologna, where the temperature reached 38C.
“He called my mother to tell her that he’d come home to prepare lunch, that he’d be home by noon,” his son Salah told Italian TV station Antena 3.
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Europe’s fourth-hottest summer
This summer was Europe’s fourth-hottest on record. Temperatures climbed as high as 46C in Spain and Portugal, forcing closures of major tourist sites including the Acropolis in Athens and the Eiffel Tower in Paris.
The researchers said it was not yet possible to compare their findings with official mortality data because most countries take months to release such figures.
“It’s impossible to get real-time statistics right now,” Otto told a press conference, adding that the estimates were “in the right ballpark.”
The analysis has not yet been peer reviewed, but it uses established methods applied in earlier studies. A Nature Medicine study estimated more than 47,000 heat-related deaths across Europe in 2023, while another study put the 2022 toll above 60,000.
“What makes this finding even more alarming is that the methods used in these attribution studies are scientifically robust, yet conservative,” said Akshay Deoras, an atmospheric science researcher at the University of Reading.
“The actual death toll could be even higher.”
