Research shows that heat exposure of older people around the world will double by 2050

Heat exposure among older people will at least double on all continents by 2050, according to a study that highlights the combined risk of a warming world and an aging population.

Compared to today, there will be up to 250 million additional people aged 69 or older exposed to dangerous levels of heat, defined as 37.5 degrees Celsius. The paper warned that this is likely to create hotspots for biological and social vulnerability with increasing concentrations of older adults and high temperatures.

The impact on healthcare systems and global inequality will be enormous. the newspaper published in Nature Communications warned, because older people are more vulnerable to high temperatures and the populations that will be hardest hit tend to be in the warmer, poorer south of the world.

The world population is aging at an unprecedented pace. It is expected that by mid-century the number of people aged 60 or over will double to 2.1 billion, which will be more than one in five people on earth. “Two-thirds of them will live in low- and middle-income countries where extreme climate events are particularly likely,” the paper predicted.

There is a striking north-south divide on most continents, with the hotter, poorer Southern Hemisphere hit harder than the cooler, richer Northern Hemisphere.

In terms of total population, Asia will experience levels of heat exposure of older adults that are almost four times higher than other regions, due to both its large population and warm climate. But every region will see a huge increase. Compared to today, exposure in South America and Europe will triple by 2050, and almost double in Oceania, North America and Africa.

Aging trends are most pronounced in Europe, where a quarter of people will be over 69 years old by 2050, and in North America, where a fifth will be in this category. But in absolute numbers, Asia and Africa will see a larger increase because their populations are much larger. These continents are also hotter and poorer, meaning they will face significantly greater burdens.

The human body has a reduced ability to thermoregulate as it ages. Older people are also more likely to have chronic diseases, such as heart and respiratory problems, which worsen the risks of heat exposure. A greater proportion are physically weak, live alone and depend on medications that cause dehydration, such as diuretics, laxatives and bumetanide (which reduces extra fluid in the body).

During recent heat waves, the death toll tends to be higher among the elderly, especially those who have difficulty walking or live in sheltered housing with insufficient air conditioning. Cases cited by the paper include the deaths of 3,500 older adults during the 2015 heat wave in India and Pakistan, the high death rates among the elderly during the 2022 European heat wave and the deaths of residents in a Florida nursing home after a power outage in 2017.

Previous climate-demographic risk studies looked at figures at the national level. The new article provided a more detailed analysis of figures at the sub-national level. This is important because climate impacts vary enormously from region to region within countries, especially within geographically large, populated countries such as China, India and Indonesia. Both cumulative exposure to prolonged high temperatures and acute exposure to short periods of extreme heat were also measured.

Much of the social burden will fall on taxpayers, whose numbers will fall in many countries facing declining fertility and a shrinking share of the working-age population.

“This is an issue of intergenerational inequality,” says one of the authors, Giacomo Falchetta of the CMCC Foundation in Venice, Italy. “The other important message is the inequality story. Countries in the Global North and Global South are very differently equipped to deal with this challenge. Societies with more infrastructure and knowledge are much better protected. This impact study clearly shows that there is a need for an adjustment mechanism for the equity issue.”

Falchetta said he hoped the projections would help societies be better prepared. He said households should ensure that the elderly have enough money for air conditioning, cities should prepare more shaded areas and green spaces, and national governments should adjust medical systems and public health information policies.

After 2050, the picture is less clear because population trends are harder to predict this far into the future and the rate of global warming will depend on the actions governments take today. But even if the overall human population begins to decline – as many demographers expect – it will continue to age and warm for some time.