The number of days where extreme heat makes it too dangerously hot to walk the dog, sweep the porch and engage in other ordinary pursuits has doubled around the world over the last 75 years, according to new research.
Scientists determined that on average, those 65 and older experience a month a year when heat prevents them from routine activities. Parts of Asia, Africa, Australia and North America are becoming unlivable for senior citizens, the researchers said. Younger adults also are losing time as climate-driven heat restricts their lives for 50 hours a year.
Overall, more than a third of the global population resides in regions where heat severely affects daily life, according to the peer-reviewed paper published Tuesday in the journal Environmental Research: Health.
Although previous research has shown the effect of extreme heat on human health, authors of the new study said it’s the first to document the consequences of rising temperatures on everyday life.
“Extreme heat isn’t just affecting our ability to survive or work physically demanding jobs, but also just to do simple, light, daily tasks,” said Luke Parsons, a climate scientist at the environmental nonprofit the Nature Conservancy and lead author of the paper.
The researchers analyzed heat and humidity records from 1950 to 2024. They used the United Nations’ Human Development Index, which measures each country’s health and living standards, as a proxy for vulnerability to rising temperatures. The scientists, who developed a physiological model of heat effects on different age groups, determined when it becomes too hot for people to undertake tasks when exposed to outdoor temperatures in the shade.
In Qatar, for instance, heat now makes it risky for older adults to engage in routine activities for a third of the year. Even 18- to 40-year-olds in that country must curb daily tasks for more than 800 hours a year or 10% of their time.
Senior citizens in the U.S. have 270 fewer hours they can devote to normal activities due to the risks of overheating. In the southern U.S., “we’re looking at many hundreds of hours of livability limitations for older adults every year,” Parsons said.
Those areas, along with Europe, southern South America, southern Australia and parts of Asia and Africa, have seen the largest increases in restrictions on daily life since 1995, according to the paper.
Study co-author Jennifer Vanos, an associate professor at Arizona State University who studies urban extreme heat, said the research shows that overheating can pose a threat to people such as restaurant workers who do a lot of low-exertion walking on the job. “Even though we don’t see that as high-intensity physical activity, it could turn into a very dangerous situation because of their exposure to heat over time,” she said.
Although citizens of wealthy nations such as Qatar and the United Arab Emirates can seek refuge in air-conditioned homes, Parsons noted those countries depend on large populations of migrant laborers working in construction and other outdoor jobs.
Global temperatures hit a record high in 2024, a year in which warming exceeded 1.5 degrees Celsius on an annual basis for the first time. “This study provides us with a really grim, unfortunate glimpse into what potentially a 1½-degree-warmer world looks like,” Parsons said.
Woody writes for Bloomberg.
