Wang Jimin
Wang Jimin
By mid-century, nearly a quarter of the world’s older people could be exposed to extreme heat that could put their health at risk.
By 2050, as many as 246 million additional adults aged 69 and older could experience extreme temperatures exceeding 37.5 degrees Celsius, the researchers reported on 14 May in Nature Communications. The new projections suggest that more than 23% of the world’s older population — mostly in Africa and Asia — will experience such heat, up from just 14% today.
“Protecting our elderly population is going to become increasingly important in the coming years,” said Andrew Chang, a cardiologist and epidemiologist at Stanford University and the University of California, San Francisco, who was not involved in the study. “Older adults are extremely vulnerable to the effects of heat.”
Exposure to heat is physiologically demanding, and there is a limit to how much heat the body can tolerate. Heat is particularly dangerous for older adults for a number of reasons. Aging bodies cannot cool down effectively. Older adults often have chronic medical conditions that are exacerbated by heat, such as cardiovascular disease or diabetes. People in this age group often take medications for dehydration. Some older adults are socially isolated, have limited mobility, or have cognitive impairments.
“It’s this perfect storm of biological aging, social loneliness, and cognition that makes older adults more vulnerable to heat stroke,” said Deborah Carr, a sociologist on aging at Boston University.
Carr and his colleagues projected the number of people aged 69 and older in 2050 and estimated the impact of climate change on the regions where these older people will live. The researchers assessed chronic heat exposure -- prolonged exposure to uncomfortable heat -- and acute exposure, which is brief but extreme, such as during a heat wave. The team found that chronic exposure will increase globally by 2050 by calculating the average temperature for all days of the year and determining how many degrees each day the comfort temperature threshold was exceeded.
In terms of heat, the number of days per year above 37.5 degrees Celsius will increase globally, from an average of 10 to around 20. The upper limits of extreme heat will also rise, depending on the region. "Both the frequency and the intensity will increase due to climate change," said Giacomo Falchetta, a climate change researcher at the Euro-Mediterranean Climate Change Centre in Venice.
The team also looked at the impact of two factors, aging populations and rising temperatures, to see which factor was driving the projections for different regions. In the historically hotter Southern Hemisphere, populations are becoming increasingly older. The global north, which is "colder and older," "is experiencing more extreme heat," Carr said.
Falchetta said there is no one-size-fits-all approach to reducing the risk of heat exposure among older adults, but options include strengthening health care infrastructure, ensuring adequate nutrition and hydration, implementing heat warning systems, providing public cooling centers and expanding green space and tree cover to reduce the urban heat island effect.
As for the study's projections, Falchetta said there are still uncertainties about the climate, which depend on reductions in greenhouse gas emissions. As for population changes, "these people have already been born -- they're just like me," he said. Countries need to "start planning now for how to meet the future needs of these people."
