Oct 23 – Europe’s record-breaking summer heat contributed to more than 50,000 deaths across 854 cities, with human-caused climate change responsible for approximately 32,600 of those fatalities, according to research scheduled for publication in Nature Health. The findings highlight the growing public health consequences of rising temperatures, as repeated heat waves across the continent exposed millions of people to dangerous conditions.
Researchers estimated that 50,391 people died from heat-related causes during June, July and August 2026. Of that total, 32,619 deaths were attributed to additional warming caused by human activities, particularly the burning of coal, oil and natural gas. The analysis indicates that temperatures intensified by climate change accounted for nearly two-thirds of the estimated summer heat death toll.
The number of deaths was approximately 71% higher than the previous record identified by the research team, which recorded 29,480 heat-related deaths in the same group of European cities during the summer of 2022.
However, the researchers cautioned that the latest figures do not represent the full extent of heat-related mortality across Europe. The analysis excluded a deadly heat wave in May and covered only 854 cities, representing approximately 40% of the continent’s population. The overall death toll could therefore be higher than the estimate.
The findings come as European countries face increasing pressure to prepare their cities, health services and public infrastructure for more frequent episodes of extreme heat. Researchers say the combination of rising average temperatures, intense seasonal heat waves and inadequate protection for vulnerable populations is increasing the danger posed by hot weather.
Clair Barnes, a climate scientist at Imperial College London and the study’s lead author, said much of Western and Northern Europe lacked infrastructure designed to withstand the temperatures now being experienced as a result of human-caused warming.
The consequences extend beyond discomfort during unusually hot weather. Prolonged exposure to high temperatures can place significant strain on the body, particularly among older people and those who have limited access to cooling or live in buildings that retain heat.
Garyfallos Konstantinoudis, a biostatistician at Imperial College London and a co-author of the research, said approximately one-third of the estimated deaths occurred between June 17 and July 1. During that period, a particularly intense heat wave pushed temperatures about 9.5 degrees Fahrenheit, or 5.3 degrees Celsius, above normal.
Some European cities experienced temperatures as much as 21.6 degrees Fahrenheit, equivalent to 12 degrees Celsius, above their usual levels, Barnes said.
Italy, France, Spain and Germany recorded the highest estimated numbers of heat-related deaths in the study. Separately, an earlier analysis by the same research team found that Rome had the highest cumulative heat death toll among European capitals between 2000 and 2025.
Climate Change Intensifies Heat Risks Across Europe
The researchers said the summer’s extreme conditions reflected both naturally occurring weather patterns and the additional warming caused by greenhouse gas emissions. Although periods of unusually hot weather can occur without human influence, the warming of the planet makes extreme temperatures more likely and increases the severity of many heat waves.
Europe is the world’s fastest-warming continent, according to Barnes, with average temperatures approximately 2.5 degrees Celsius above pre-industrial levels. The Arctic is warming even faster, although it is a region rather than a continent.
The additional warming may appear relatively small when expressed as a difference in average global or regional temperatures. However, scientists say even a modest increase can push temperatures beyond dangerous thresholds, particularly during prolonged heat waves.
Barnes explained that the extra warming caused by human activity can turn conditions that might otherwise be uncomfortable into situations that threaten human health and life.
The age distribution of the estimated deaths illustrates the unequal impact of extreme heat. More than half of those who died during the summer were aged 85 or older, according to Konstantinoudis. Nevertheless, the effects were not confined to the elderly. The researchers also estimated that more than 800 people between the ages of 20 and 44 died from heat-related causes.
Older people are particularly vulnerable because the body’s ability to regulate temperature can decline with age. People living alone, those with existing health problems and individuals without reliable access to air conditioning or other cooling facilities can face additional risks. The study’s findings underscore the need for public health measures that reach vulnerable residents before temperatures become dangerous.
To estimate the number of deaths attributable specifically to climate change, the research team compared actual conditions with computer simulations of a hypothetical world without human-caused climate change. The difference between the modeled outcomes and the estimated deaths under real-world conditions provided an assessment of the additional mortality linked to human-driven warming.
The researchers used an established scientific approach that accounts for differences in temperature, age and local conditions. Their calculations considered the temperature associated with the lowest mortality risk in each city, then estimated how deaths increased when conditions became warmer or colder than that level.
The team also compared its estimates with figures published by government agencies. Konstantinoudis said the results generally aligned reasonably well with official assessments, although the figures did not match in every case. For British heat waves in May and June, the researchers calculated approximately 2,700 excess deaths, compared with an estimate of 2,800 from the United Kingdom’s health statistics agency.
Estimating heat-related mortality remains challenging because heat is frequently underreported as a contributing factor on death certificates. People may die from cardiovascular or respiratory complications aggravated by high temperatures without heat itself being identified as the primary cause. Statistical modeling therefore provides an important way to assess the broader public health impact.
Howard Frumkin, a former director of the National Center for Environmental Health in the United States who was not involved in the study, said increasingly hot summers and improvements in analytical methods were producing higher and more reliable estimates of heat-related deaths.
The researchers also found that the proportion of heat deaths attributed to global warming has increased over time. Barnes said the share rose from approximately 45% in the early 2000s to around 65% in the latest estimates, reflecting the growing contribution of human-caused warming to dangerous temperatures.
Heat Protection Must Be Matched by Emissions Cuts
Public health specialists say European governments need to strengthen their preparations for extreme heat while addressing the emissions that drive long-term warming. Measures such as early-warning systems, accessible cooling facilities and community support networks can reduce immediate risks, particularly for people who are elderly, isolated or otherwise vulnerable.
Dr. Courtney Howard, a Canadian emergency room physician and president-elect of the Canadian Medical Association, said communities needed urgent investment in heat alerts, equitable access to low-carbon cooling and neighborhood programs that check on residents most at risk. She also emphasized the need to reduce fossil fuel consumption, which is a major driver of the climate crisis.
Such measures can help authorities identify dangerous conditions earlier and encourage people to take protective action. Cities can also reduce exposure through better building design, shaded public spaces, urban greenery and improvements to housing that help keep indoor temperatures manageable.
However, experts warn that adaptation alone cannot eliminate the growing threat. As temperatures continue to rise, even well-prepared communities may face increasing pressure on hospitals, emergency services, electricity networks and public infrastructure.
Dr. Jonathan Patz, a professor of health and the environment at the University of Wisconsin-Madison who was not involved in the research, said efforts to protect people from heat must be accompanied by action to address its underlying causes. He argued that improving cooling and protecting vulnerable populations were necessary, but governments also needed to reduce fossil fuel use.
The distinction is important because adaptation addresses the consequences of warming, while emissions reductions can limit the severity of future climate change. Without action on both fronts, public health systems could face increasingly difficult conditions as extreme heat becomes more frequent and intense.
The study’s estimates provide another indication of how climate change is affecting human health beyond its effects on ecosystems, agriculture and infrastructure. The reported deaths also demonstrate the importance of recognizing heat as a significant public health hazard, even when it is not consistently recorded as the direct cause of death.
With the 2026 summer toll already exceeding the previous record identified by the researchers, the findings raise urgent questions about whether European cities are adequately prepared for future heat waves. The researchers stressed that the figures cover only a portion of the continent’s population and exclude the deadly heat experienced in May.
As governments assess their climate policies and emergency preparedness, the research points to a growing challenge: protecting people from extreme temperatures that are already occurring while reducing the emissions responsible for making those conditions more dangerous.