July 2023 was the hottest month ever recorded. It could even be the hottest month in human history.
And it’s just one in a chain of broken heat records (SN: 7/13/23). A record-breaking heat wave is still lingering in the U.S. Southwest. In 2020, temperatures jumped to 38° Celsius in Siberia, marking the highest ever recorded in the Arctic Circle (SN: 7/01/20). Nine of the 10 hottest years on record have taken place in the last decade.
That heat has tested the limits of our very bodies to tragic effect: In 2003, an estimated 70,000 people died from a European heat wave. In 2022, another heat wave there caused some 62,000 deaths. Thousands more have died in other extreme heat events, and even more have suffered heat illness or injury.
The human body can adapt to heat, but only to a certain point, research has shown (SN: 7/27/22).
“The body works quite hard to keep the core body temperature within a pretty narrow range,” says Kristie Ebi, who researches climate change and health at the University of Washington in Seattle. “If you can’t cool down that core body temperature, then your cells and your organs start being affected.”
Sustained heat waves place our bodies under strain, which can set off a cascade of effects that can lead to permanent injury or death, Ebi and colleagues wrote in a 2021 review in the Lancet. Heat waves are also getting more humid, limiting our ability to cool down, and nights are growing hotter, cutting into the time we might rest and recover. Both these trends undercut our ability to adapt to rising heat.
While people have ways to keep themselves and their communities safe, heat risks will only increase with rising temperatures, researchers say. Here’s what extreme heat and high humidity do to the body — and how you can protect yourself.
Humid heat waves, hot nights
The body has two main pathways to keep cool. First is sweating. As body temperature rises, sweat glands in the skin release salty…
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