How heat changes our bodies (and we'll sweat even more in the future)

Our bodies are undergoing physiological changes to better withstand the increasing heat and more frequent periods of extreme temperatures. As global temperatures rise, humans are becoming more resilient, improving their ability to tolerate heat and cool themselves efficiently. This adaptation is particularly noticeable in the short term, as the summer heat accumulates.

"The longer the summer lasts, the better our body is adapted to it," explains climate doctor Jules Vertriest. "We will sweat more efficiently, meaning that over time, we will sweat out less salt than during the first warm days of spring or summer."

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The longer the summer lasts, the better our body is adapted to it. We will sweat more efficiently, meaning that over time, we will sweat out less salt than during the first warm days of spring or summer.

Hein Daanen, a professor of thermophysiology at the Vrije Universiteit Amsterdam, adds that it takes about ten days for the body to truly acclimatize. "We retain more fluid quickly, but our sweat glands need a bit more time." These are temporary adjustments that can also manifest in the long term, although long-term studies are still needed for confirmation.

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We retain more fluid quickly, but our sweat glands need a bit more time.

Evidence of this adaptation can be seen in mortality statistics. Professor Daanen observed fewer deaths at equal heat loads compared to the past when comparing Dutch mortality rates with ambient temperatures. Southern European countries, where residents are accustomed to prolonged periods of high temperatures, offer another example. While a Belgian tourist might struggle in the heat, an Italian in a suit walks by unaffected, demonstrating a difference in "sweat threshold" influenced by factors like weight, ethnicity, physical condition, clothing, and even life stage.

"Genes also play an important role," Vertriest notes. Prolonged exposure to moderate heat can create a form of "memory" in our genes, guiding the body on how to respond to extreme heat. This might explain why communities that have lived in warm regions for generations are better adapted.

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Genes also play an important role. By prolonged exposure to moderate heat, a kind of memory can arise for what to do in case of extreme heat.