A first-of-its-kind rapid analysis has concluded that human-induced climate change caused approximately 1,500 deaths during last week’s European heat wave. According to the study, these fatalities would not have occurred without the burning of fossil fuels over the past century.
“These deaths are directly attributable to climate change—they would not have happened without the additional warming from oil, coal, and gas emissions,” said co-author Friederike Otto, a climate scientist at Imperial College London.
Researchers from Imperial College and the London School of Hygiene & Tropical Medicine used established scientific methods to estimate that around 2,300 people died from the extreme heat across 12 major European cities. Nearly two-thirds of these deaths—about 1,500—were linked to the extra heat intensified by climate change.
Unlike previous rapid attribution studies, which focused on climate change’s role in extreme weather events, this research directly connects fossil fuel emissions to increased mortality.
“Heat waves are silent killers, and their death toll is often underestimated,” said co-author Gary Konstantinoudis, a biostatistician at Imperial College. “Because heat is rarely listed as an official cause of death—instead being attributed to heart failure, respiratory issues, or other conditions—the true impact is hidden.”
The study found that over 1,100 of the climate-related deaths were among people aged 75 or older.
“While summer heat is normal, climate change has raised temperatures by several degrees, pushing vulnerable populations into life-threatening conditions,” said lead author Ben Clarke. “For some, it’s just warm weather—but for others, it’s deadly.”
The analysis examined cities including London, Paris, Madrid, and Rome between June 23 and July 2. In most locations, greenhouse gas emissions added 2–4°C (3.6–7.2°F) to the heat wave, with London experiencing the highest increase. Lisbon was an exception, with only a 1°C rise due to the Atlantic Ocean’s cooling influence.
Milan, Barcelona, and Paris saw the highest number of additional deaths from climate-amplified heat, while Sassari, Frankfurt, and Lisbon had the lowest. The 1,500 figure represents the mid-range estimate, with potential deaths ranging from 1,250 to 1,700.
Though not yet peer-reviewed, the study builds on methods used by climate scientists to attribute extreme weather to global warming, combined with epidemiological research on excess mortality. Researchers compared real-world temperatures to climate models simulating a world without fossil fuel emissions, then analyzed heat-related deaths against expected baselines.
“This study removes any doubt about the deadly consequences of fossil fuel dependence,” said Dr. Jonathan Patz of the University of Wisconsin, who was not involved in the research. “It shows that even small temperature increases have severe health impacts.”
Dr. Courtney Howard, an emergency physician and climate health advocate, added, “Research like this proves that cutting fossil fuel use isn’t just environmental policy—it’s lifesaving healthcare.”
The Associated Press’ climate coverage is supported by multiple private foundations. AP maintains full editorial control over all content.