Heat index outpacing actual temperature increases

There is already overwhelming evidence showing that climate change is causing global temperature increases. Now, new research has shown that not only are temperatures rising, but the other factors that affect how we feel heat might be intensifying at an even greater rate.

According to a University of California study of climate data in Texas from June to August 2023, the 1.5°C average heat increase Texas experienced during its summer heatwaves actually feels like a 5–6°C increase. This is according to a revised heat index the researchers used to calculate a “feels like” temperature.

The study’s author, David Romps, says the current method used for calculating the heat index – dating back to 1979 – doesn’t accurately reflect the interplay between heat and humidity, which has changed as the planet has warmed.

In the past, relative humidity usually dropped when the temperature increased, allowing the body to sweat more. But with climate change, the relative humidity remains similar as the temperature increases, reducing how effectively sweating cools the body.

“I picked Texas because I had seen some high heat index values there that made me think, OK, this is a state that this summer is probably experiencing combinations of heat and humidity that are not being captured properly by NOAA’s approximation to the heat index,” Romps says.

Beyond comprehension

During the study, Romps saw one value that stood out. On July 23, 2023, he calculated that the heat index was 75°C, of which 6°C was attributable to climate change.

“It sounds completely insane,” Romps says. “It’s beyond the physiological capacity of a young, healthy person to maintain a standard core temperature.”

While this sounds deadly, and for many people would be, Romps and his colleagues argued that a young, healthy person could survive such a temperature.

“We think if you kept your skin wet and you were exposed to 167 degrees, even though we’re approaching something like a setting on the oven, you’d still be alive,” he says. “Definitely not happy. But alive.”

Image courtesy of Nathan Dumlao via Unsplash.

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