The average young adult could be experiencing up to 50 hours a year of severe heat-related limitations in livability and the average older adult up to 900 hours a year of the same, an analysis of data from the European climate agency Copernicus Climate Change Service has estimated.
The study, published in the journal Environmental Research Health, defines ‘livability’ as one’s ability to perform everyday physical activities requiring an elevated heat production in the body without suffering ill effects.
Researchers, including those from the US’ universities of Utah and California (Irvine), found that 78 per cent of the world’s population lives in areas that would severely limit activity for older adults aged 65 and above during the hottest hours of a year and 35 per cent in areas severely limiting activity for younger adults (age 18 to 40).
“These livability limitations are not just limited to the single hottest hour of the year; the average younger adult now experiences (nearly) 50 hours per year of severe heat-related livability limitations. Similarly, the average older adult experiences (nearly) 900 hours per year of severe livability limitations,” authors wrote.
The team analysed climate and weather data recorded during 1950-2024 and managed by Copernicus Climate Change Service.
During 1995-2024, temperature and humidity in the hottest hours of the year already limit the livability of both younger and older adults to lying down and sitting in parts of the tropics and subtropics, the analysis revealed.
For older adults, limitations in livability during the hottest hours of a year were found to be more equally spread across countries with varying levels of vulnerability — the most severe limitations seen in southwest Asia, including Qatar, Kuwait and the United Arab Emirates, and south Asian nations, such as India.
Further, average number of hours with severe livability limitations for younger and older adults during 1995-2024 were assessed to show that south and southwest Asia experience the most number of hours of heat-related limitations per year.
For younger adults, limitations exceeding one thousand hours per year — more than a month of livable hours lost per person — are concentrated in southwest Asia.
Limitations exceeding one hundred hours per year were found in southwest Asia, south Asia including India, Pakistan and Bangladesh, Vietnam in southeast Asia and China in east Asia.
For older adults, the highest number of hours of severe limitations per year are more evenly geographically distributed across tropical and sub-tropical low-elevation locations, the researchers said.
Locations with at least 1,500-2,000 hours of severe livability limitations per year — about a third to half of daytime hours during a calendar year — include southwest, south and east Asia, along with tropical South America, the tropical Atlantic, tropical western sub-Saharan Africa.
“Hot areas are only becoming less livable as the globe warms, and climate model projections confirm that this historical trend is expected to continue,” authors said.
They added that many locations already hot enough to experience severe heat-associated livability limitations, including southern Asia, are also expected to experience rapid future population growth.
“We hope this work motivates rapid emissions reductions to slow global warming and limit future extreme heat impacts,” the team said.
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