Climate Change Contributed to Over 32,000 Heat Deaths in Europe This Summer, Study Finds

Blistering heat waves this summer in Europe contributed to more than 50,000 deaths, with nearly two-thirds of that total attributed to human-caused climate change, according to a new study.

Researchers analyzed heat-related mortality across 854 European cities during heat waves in June, July, and August. They found that 50,391 people died due to elevated temperatures. Of those deaths, 32,619 were linked to the additional heat generated by the burning of fossil fuels, the study published in Nature Health indicated.

This summer's death toll represents a significant increase compared to the previous deadliest summer, which saw 29,480 heat-related deaths in 2022, according to the same research team. The study's authors noted that these figures are likely underestimates, as they do not include a deadly heat wave in May and focus only on 854 cities, which constitute about 40% of Europe's population.

One particularly intense heat wave from June 17 to July 1, when temperatures in parts of Europe were 9.5 degrees Fahrenheit (5.3 degrees Celsius) above normal, accounted for about one-third of the total deaths, said Garyfallos Konstantinoudis, a biostatistician at Imperial College London and co-author of the study.

"Much of Western and Northern Europe, our infrastructure is just not designed to cope with the sort of temperatures that we are seeing now because of the effects of human-caused warming," said lead author Clair Barnes, a climate scientist at Imperial College London. She noted that some European cities experienced temperatures 21.6 degrees Fahrenheit (12 degrees Celsius) warmer than average this summer.

Europe is warming faster than any other continent, with temperatures 4.5 degrees Fahrenheit (2.5 degrees Celsius) higher than pre-industrial times. "Just the underlying warming from human activity, from mostly the burning of fossil fuels, it's increasing all of our temperatures by what sounds like quite a small amount," Barnes explained. "For many people, it's certainly the case that that extra two-and-a-half degrees (Celsius) of warming is what’s going to tip those temperatures from uncomfortable to dangerous and potentially deadly."

The study also revealed that more than half of the individuals who died were aged 85 or older. However, the extreme heat also led to the deaths of over 800 people between the ages of 20 and 44, Konstantinoudis reported.

To determine the impact of climate change, the researchers employed a widely accepted scientific method. They conducted computer simulations of a world without human-induced warming and compared the results to the actual mortality data from this summer. The difference between these two scenarios represents the deaths attributable to global warming.

The proportion of heat deaths linked to global warming has risen from approximately 45% in the early 2000s to 65% currently, according to Barnes.

Experts not involved in the study acknowledged the findings. "Summers are getting hotter, and the analytical tools for attributing deaths to heat are getting more accurate," said Dr. Howard Frumkin, former director of the National Center for Environmental Health in the U.S. "Together, these two trends yield increasingly high and increasingly accurate counts of heat-related deaths."

The researchers utilized statistical modeling to estimate the base figure of 50,000 heat deaths, acknowledging that such fatalities are often underreported and not always explicitly recorded on death certificates, despite being a significant contributing factor. Outside experts confirmed the state-of-the-art nature of the team's methodology.

The team's calculations were based on a complex mathematical equation used in prior peer-reviewed studies. This model considers specific age demographics and local temperature data for each of the 854 cities, referencing an optimal temperature associated with the fewest deaths. The equation then quantifies excess deaths when temperatures deviate from this optimum.

Constantinoudis mentioned that these calculations were cross-referenced with real-time estimates from government agencies, showing a reasonable alignment. For instance, the team's calculation of 2,700 excess deaths during heat waves in Britain in May and June closely matched the United Kingdom's health statistics agency figure of 2,800.

Dr. Courtney Howard, president-elect of the Canadian Medical Association, who was not part of the research, emphasized the need for immediate action. "We need to prepare for the heat we cannot now avoid, with urgent investments in heat early-warning systems, equitable access to low-carbon cooling, and neighborhood buddy systems that check on and support people most at risk — while rapidly reducing the fossil fuel use driving the crisis."

Dr. Jonathan Patz, a professor of health and the environment at the University of Wisconsin-Madison, also praised the study and stressed the importance of addressing the root cause. "We can’t just be mopping up the mess on the floor without thinking about turning the faucet off," Patz said. "So we need prevention at different levels. We need better cooling and protecting vulnerable populations from inevitable increased frequency and extreme heat waves. But we also need to go to the root of the problem and absolutely address the burning of fossil fuels."