Stanford Study: Heat Waves More Dangerous for the Elderly
Researchers warn that previous models underestimated the risk because they were based on young and healthy subjects. By 2100, billions of people over 60 could face unbearable conditions.
Researchers warn that previous models underestimated the risk because they were based on young and healthy subjects. By 2100, billions of people over 60 could face unbearable conditions.
A new study by researchers at Stanford University, published on Tuesday, August 18, 2026, in The Lancet Planetary Health, warns that the danger of high temperatures combined with humidity for the health of older adults has been dramatically underestimated for years.
The main problem, as the authors note, lies in the methodology of previous research. These studies largely relied on a metric known as the wet-bulb temperature, but experiments were conducted on young, healthy adults. However, older people sweat less, often have weaker hearts, and pre-existing health conditions, which significantly alters their heat tolerance thresholds.
To correct this shortcoming, the researchers used data from recent experiments conducted in the United States on individuals over 60. Considering the aging global population, they analyzed how heat affects three different age groups up to 2100, under various global warming scenarios.
The results are alarming. In the case of a 1.5-degree Celsius rise in global temperature compared to pre-industrial levels, it is projected that 22 percent of people over 60 will spend at least one month each year in dangerous heat conditions. Every additional degree of temperature increase will result in about one billion people being exposed to a month of heat and humidity that exceeds their body's ability to cope.
With a 3-degree Celsius warming, older adults in the hardest-hit regions, South Asia and the Persian Gulf countries, could face dangerous heat day and night for three consecutive months each year.
"Unbearable heat will occur on a much larger scale and last longer, affecting far more people than previously estimated," the researchers concluded.
The study specifically highlights countries with high levels of poverty and limited access to cooling as facing the greatest threat. These include India, Pakistan, Bangladesh, Myanmar, and Niger.
The researchers also warn of broader social consequences. "These results suggest that unbearable heat could increasingly drive internal displacement and cross-border climate migration, creating new challenges for public policy and humanitarian efforts," the study states.
The study was released during a summer in the Northern Hemisphere marked by extreme heat. Europe, the fastest-warming continent in the world, has faced wildfires, prolonged heatwaves, and droughts, and this summer is expected to be the hottest on record. France has been one of the hardest-hit countries with several heatwaves, including one of unprecedented scale in late June, leading to a rise in mortality.
To avoid these grim scenarios, the authors call for reducing greenhouse gas emissions and prioritizing the protection of vulnerable older adults in future heat action plans. Since most heat-related deaths occur indoors, they particularly emphasize the importance of "broader access to air conditioning and other cooling options."
