More than 50,000 people died of heat in European cities in the summer of 2026, and about two-thirds of those deaths are attributable to warming caused by human activity. That is the estimate of two studies published on Friday in the journal Nature Health by researchers at the London School of Hygiene & Tropical Medicine (LSHTM) and Imperial College London.
The model's central figure is 50,391 deaths between 1 June and 31 August — the highest in the authors' series, which begins in 2000, and almost double the summer of 2022, which came in at around 29,000.
Where and when
The analysis covers 854 urban areas in 30 countries: the 27 of the European Union plus the United Kingdom, Norway and Switzerland. About 40% of those countries' populations live in them.
Almost a third of the deaths fell within two weeks, between 17 June and 1 July, when the daily mean temperature across the region ran more than 5°C above the 1991-2020 average.
Southern and western Europe recorded the highest temperatures and the highest mortality rates. In the west of the continent, the average summer anomaly was about 2.9°C above the 1991-2020 baseline, with individual days as much as 12°C above normal for the time of year. Northern Europe was significantly affected too.
By country, according to the figures released, Italy recorded 13,303 deaths; France, 7,268; Spain, 6,824; and Germany, 6,340. The United Kingdom came in at about 4,500 deaths, spread across the 135 British urban areas included in the analysis.
Not only the elderly
Older people remain the group most affected, but the study estimates about 6,000 deaths among people under 65 — a slice that tends to be left out of the public conversation about heat, usually treated as a problem exclusive to the elderly.
Twenty-six years of data
The second paper applies the same method to the same 854 areas across the summers of 2000 to 2025 and arrives at more than 430,000 heat-related deaths over the period. The share attributable to human-induced warming rose from about 40% in 2000 to more than two-thirds in 2025 — meaning what changed is not only the total number of deaths, but how much of that total climate change explains.
How the number is built — and what it is not
The researchers calculated daily temperatures for the 854 areas from weather observations and climate models, and compared the present climate — already about 1.4°C warmer than pre-industrial times — with a hypothetical climate without human-caused warming. On top of those temperatures they applied previously published relationships between daily temperature and all-cause mortality. The difference between the two scenarios is what the study calls mortality attributable to climate change.
These are therefore modelled estimates, not a count of death certificates — a caveat the authors' own material states. They depend on assumptions about the exposed population and on temperature-mortality curves derived from each area's historical records. LSHTM says earlier estimates produced this way have come close to the figures later published by national health authorities.
What the authors are calling for
"This summer has been another dramatic reminder that climate change is everybody's problem," said Pierre Masselot of LSHTM, a co-author of both papers. Garyfallos Konstantinoudis, of Imperial College's Grantham Institute, said the relationship between higher temperatures and more heat deaths is "well established and statistically robust".
Alongside emissions cuts, the authors recommend heat-health warning systems, adapting homes and healthcare facilities, and urban planning that delivers shade and green space. Clair Barnes, of Imperial College and lead author on both papers, sums up the finding as a reminder that hotter, more extreme summers are having an increasingly severe effect on public health.
With information from the London School of Hygiene & Tropical Medicine, Imperial College London and the newspaper The National.
