August 26, 2025
3 min read
Repeated Heat Waves Can Age You as Much as Smoking or Drinking
A new long-term study suggests that the more heat waves people are exposed to, the more their body’s aging process accelerates
An elderly man is seen resting under a tree at Levico lake. With temperatures exceeding 45 degrees Celsius in many parts of Italy, and wildfires burning in France, Spain and Portugal, Europe is under under alert as the heatwave grips the continent.
Davide Bonaldo/SOPA Images/LightRocket via Getty Images
Long-term exposure to extreme heat events accelerates the body’s ageing process and increases vulnerabilities to heath issues, finds a long-term study of 24,922 people in Taiwan.
The study, published today in Nature Climate Change, suggests that moderate increases in cumulative heatwave exposure increase a person’s biological age — to an extent comparable to regular smoking or alcohol consumption. The more extreme-heat events that people were exposed to, the more their organs aged. This is the latest study to show that extreme heat can have invisible effects on the human body and accelerate the biological clock.
Exposure to extreme heat, especially over long periods of time, strains organs and can be lethal, but “the fact that heatwaves age us is surprising”, says Paul Beggs, an environmental-health scientist at Macquarie University in Sydney, Australia, who was not involved in the research. “This study is a wake-up call that we are all vulnerable to the adverse impacts of climate change on our health. It reinforces calls for urgent and deep reduction in greenhouse-gas emissions,” he adds.
On supporting science journalism
If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
Accelerating ageing
Age isn’t just a result of time. Previous studies have linked a number of factors — including environmental and social stress, genetics and medical interventions — to signs of ageing-related physiological changes. This puts people at a higher risk of cardiovascular disease, cancer, diabetes and dementia.
To study the long-term impacts of heatwaves on ageing, the researchers analysed data from medical examinations between 2008 and 2022. During that time, Taiwan experienced around 30 heatwaves, which the study defined as a period of elevated temperature over several days. The researchers used results from several medical tests, including assessments of liver, lung and kidney function, blood pressure and inflammation, to calculate biological age. They then compared biological age with the total cumulative temperature that participants were probably exposed to on the basis of their address in the two years before their medical visit.
The study found that the more extreme-heat events that people experienced, the faster they aged — for every extra 1.3 °C a participant was exposed to, around 0.023–0.031 years, on average, was added to their biological clock.
“While the number itself may look small, over time and across populations, this effect can have meaningful public-health implications,” says Cui Guo, an environmental epidemiologist at the University of Hong Kong, who led the study.
Manual workers and people living in rural areas experienced the largest health impacts, probably because these groups are less likely to have access to air conditioning. But there was an unexpected upside: the impact of heatwaves on ageing decreased over the 15-year study period. The reasons behind this heat adaptation are unclear, but improved access to cooling technology could play a part, Guo says.
Still, “the message is that heat makes you age a bit faster than you normally would, and that this is something you would like to avoid”, says Alexandra Schneider, an environmental epidemiologist at Helmholtz Munich in Germany, who was not involved in the study.
Rising heat
In 2023, research in Germany found that higher air temperatures were associated with more epigenetic markers of ageing. And a study in more than 3,600 older people in the United States similarly concluded, through analysing DNA markers, that extreme heat prematurely aged participants.
The most recent study focused on the impact of long-term heat exposure, which is more likely to have lifelong health effects. This is important because climate change is leading to more extreme-heat events. In the United States, there are now six heatwaves each year, as of 2010 — up from two in the 1960s. Scientists estimate that climate change has made heatwaves such as the deadly 2022 ones in Pakistan and India, during which temperatures hit 50 °C, 30 times more likely to occur.
The growing frequency of heatwaves, combined with their effects on health, highlights the importance of protecting vulnerable groups, says Guo. “Heatwave is not a personal risk factor, but a global concern.”
This article is reproduced with permission and was first published on August 26, 2025.
It’s Time to Stand Up for Science
If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.
I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.
If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.
In return, you get essential news, captivating podcasts, brilliant infographics, can’t-miss newsletters, must-watch videos, challenging games, and the science world’s best writing and reporting. You can even gift someone a subscription.
There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.
