Extreme Temperature Diary Tuesday August 26th, 2025/ Main Topic: In a Hotter World, Some People Age Faster, Researchers Find

New Study Shows Heat Waves Make People Age Faster – The New York Times

In a Hotter World, Some People Age Faster, Researchers Find

Exposure to heat waves over just two years could add up to 12 extra days of age-related health damage.

A heat wave hit Taipei, Taiwan, last July.Credit…Annabelle Chih/Reuters

Sachi Kitajima Mulkey

By Sachi Kitajima Mulkey

Aug. 25, 2025

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Living through extreme heat waves can accelerate your rate of aging, according to research published Monday.

Scientists analyzed 15 years’ worth of health data from nearly 25,000 adults in Taiwan and found that two years of exposure to heat waves could speed up a person’s so-called biological aging by eight to 12 extra days.

It may not sound like a lot, but this number builds over time, said Cui Guo, an assistant professor at the University of Hong Kong who led the study, which was published Monday in the journal Nature Climate Change.

“This small number actually matters,” she said. “This was a study of a two-year exposure, but we know heat waves have actually been occurring for decades.”

The research comes as human-induced climate change is making heat waves more intense and long-lasting. The West Coast of the United States is suffering from sweltering temperatures while Iran is experiencing searing heat. Record-breaking temperatures punished Europe, Japan and Korea earlier this month. France recently experienced its second heat wave of the summer, sparking a national debate over air-conditioning.

In 2024, the hottest year on record, climate change was responsible for 41 extra days of extreme heat worldwide, according to an analysis by World Weather Attribution.

Particular groups are more vulnerable to faster aging because of heat, the researchers found. If you’re an older person who has lived through many heat waves, you may age faster than a younger person who had the same exposure, Dr. Guo said. Other factors, such as living without air-conditioning or working outdoors, can also make your aging rate significantly worse.

Dr. Guo cautions this isn’t the same as losing literal days off your life; it reflects a measurable shift in biological aging markers, not the calendar.

The study defined heat waves as both a period of at least two consecutive days of abnormally high temperatures as well as any time when officials issued heat warnings. It also took the sum of a person’s heat exposure into account.

The researchers quantified the heat’s effects by comparing people’s biological age to their chronological age. Biological age, is a measure of how healthy a person’s lungs, liver and cells are compared with a perfectly healthy person, Dr. Guo said.

The study used 12 of these health measurements, known as biomarkers, to calculate how heat affected the rate of aging for the study’s participants. The results accounted for individual factors that can affect aging markers, such as exercise, smoking and preexisting disease.

“Most countries are facing an aging population,” Dr. Guo said. Since biological aging is closely linked to death and many diseases, speeding it up can be an indicator of serious health problems.

The population of Taiwan, along with Italy, Spain and Hong Kong, ranks as one of the oldest in the world. In the United States, a little less than a quarter of the population is expected to be 65 or older by 2050.

The research published Monday builds on other studies that have found similar detrimental health effects of heat exposure. A recent analysis of 3,600 older Americans found that living in 90 degrees Fahrenheit for at least 140 days a year could cause up to 14 months of additional aging.

Unlike the study in Taiwan, the research in the United States did not account for some individual factors that might affect health, like smoking. Kristie Ebi, a professor at the University of Washington who was not involved in either study, said that such factors make a large health impact, and accounting for them is key to correctly analyzing the effects of heat on a population.

Other long term changes can make a difference too, Dr. Ebi said. Over a period as long as 15 years, a population may slowly acclimate to hotter temperatures, including finding new ways to cope with heat. The authors of the Taiwan study suggested that a moderate increase in the number of households with air-conditioners correlated to diminished aging from heat over time.

“The results may have implications for public health interventions,” said Dr. Ebi, noting that there are ways that governments can intervene to protect people in a warming world.
For example, residents of Oregon can use Medicaid funding to buy an air-conditioner if they have health conditions that can get worse in hot weather, she said. But air-conditioners should not be considered an ideal solution because the energy they use can make the outside air hotter and contribute to climate change, Dr. Ebi said.

Extreme heat can also present other, less direct risks to health. High temperatures have been found to worsen air quality, and set the stage for other disasters, such as wildfires, drought and storms.

“People just have low awareness that heat kills or that, in this case, has adverse health consequences,” Dr. Ebi said. “That’s just been a persistent challenge.”

Sachi Kitajima Mulkey covers climate and the environment for The Times.

What to Know During Extreme Heat


  • Sleeping Tips: Heat can affect both how much you sleep and how good that sleep is. These simple steps can help you get a better night’s rest when it’s hot.
  • Medications: Certain antidepressants, blood pressure pills and other drugs make you more susceptible to heat-related illness.
  • Heat Acclimatization: It’s possible to train your body to better handle high temperatures in just a few weeks. Here’s how.
  • Travel: Stifling conditions could impact your travel plans this summer. Use these tips and precautions to protect yourself and your vacation dollars.

Here is More Climate News from Tuesday:

Surface water temperatures in the Great Lakes have not only been rising, but having more extreme highs and lows. Tough for marine life to adapt. www.nature.com/articles/s43…

Dr. Jeff Masters (@drjeffmasters.bsky.social) 2025-08-25T23:23:25.722Z

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Sophie Gilbert (@sophielgilbert.bsky.social) 2025-08-25T19:33:13.471Z

"These cuts, which would hit basic science on the weather, oceans, and—especially—climate, represent a “down payment” on the White House’s proposal to eliminate NOAA’s research arm in the 2026 fiscal year that begins on 1 October, agency officials have told employees."

Zack Labe (@zacklabe.com) 2025-08-25T20:42:38.457Z

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Nathaniel Stinnett (@nathanielstinnett.bsky.social) 2024-12-16T14:23:39.736Z

I recommend this episode of CBC's The House dedicated to whether Canada can meet its climate goals (and not b/c I'm the first guest!). It'll be interesting even to non-Canadians, to hear how Canada is struggling over climate policy amid outside pressures. podcasts.apple.com/ca/podcast/s…

Simon Donner (@simondonner.bsky.social) 2025-08-25T16:57:14.209Z

Aug 26, 1965 – “Climatic Change appears to be underway” – the commencement speech that should have rocked the worldCarl Borgmann at University of Tennessee;"CO2… traps heat from the sun, and climatic change results – not overnight, but slowly and surely”allouryesterdays.info/2025/08/25/c…

All Our Yesterdays (@allouryesterdays.bsky.social) 2025-08-25T21:22:10.790Z

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Here it comes. About 20-30 mins away from me, heading right at me. This is the largest dust storm/haboobs I’ve seen in 26 years in Phoenix. Ground stop at Sky Harbor. Gusts to 67 mph there. #azwx

DazeGoneBy (@dazegoneby.bsky.social) 2025-08-26T00:30:42.107Z

My lab's been attacked by an anti-wind group and their lawyers. They threatened the science funding of my whole university, to shut me and my undergraduate research assistants up. NYT just covered it. 1/nwww.nytimes.com/2025/08/25/c…

Timmons Roberts (@timmonsroberts.bsky.social) 2025-08-25T11:32:10.044Z

Some of us have been told it's more energy-efficient and cost-effective to turn off our air conditioning when we leave home for work.

The Associated Press (@apnews.com) 2025-08-26T19:00:21Z

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