Dangerous ‘heat stress’ has surged worldwide, study shows

PARIS: The number of people exposed to dangerous heat stress worldwide has risen sharply over the last half century propelled by climate change, according to a study released on Monday (Jun 22) as Europe sweltered through a punishing heatwave.

Heat stress – the name given to the hazardous build-up of body heat caused by soaring temperatures, humidity and other factors – is one of the most common ways that weather kills people.

The new study, published in the journal Nature Climate Change, tracked how heat stress levels surged between the 1970s and 2024.

“On every continent, strong to extreme heat stress is now more frequent,” lead study author Rebecca Emerton, of the European Centre for Medium-Range Weather Forecasts, told AFP.

In the 1970s, for example, 16 percent of the world’s population experienced at least one day of extreme heat stress – when the “feels-like” temperature was at least 46C.

Fifty years later, the rate has risen to 22 per cent.

“That might not sound like so much,” Emerton said.

“But that’s an extra approximately one billion people that are seeing at least some extreme heat stress now that wouldn’t have done in the 1970s,” she added.

The study used the Universal Thermal Climate Index (UTCI), which represents the temperature it “feels like”, by including factors such as humidity, wind, radiation and how the human body responds to heat.

The daily average UTCI has been rising as heat stress events become more frequent, severe and longer-lasting due to human-driven global warming, the research found.