Extreme Heat Kills: Record Temps Leave Us All Vulnerable Liz Scherer - WebMD
go to original July 13, 2023

The Basics: Signs of Heat Exhaustion (WebMD)

If you clicked on any major news site this week, there was one consistent headline that would be difficult to miss, let alone ignore: “Hottest Day Ever Recorded on Earth.”’

That day was July 3, when average global temperatures reached 62.62 F. But that record was short-lived, as July 4 saw temperatures rise again, to 62.92. Dig a bit deeper, and that seemingly unspectacular average temperature translated into highs of 122 F in Africa. In Antarctica, where it’s currently winter, temperatures reached 47.6 F. And in the U.S., The Washington Post warned that as many as 54 million Americans were in danger of exposure to dangerous (aka “extreme”) heat on that day alone. Scientists are warning that we’re in uncharted territory. And humans are close to reaching the peak of their ability to adapt.

“When we’re talking about evolution, we’re talking about millions of years for [humans] to generate this capacity to thermoregulate,” said Camilo Mora, PhD, a professor of data analytics at the University of Hawaii-Manoa. “So, whenever you increase the temperature outside, it’s going to take millions of years for us to adapt logically to it,” he said.

Mora and his colleagues have spent decades modeling that risk of extreme heat as it relates to global climate change, showing that in the last decade, the planet has warmed by about 1 C (1.8 F), resulting in a greater than 2,300% increase in the loss of human life to heat waves alone.

Multiple Ways Heat Can Kill You

When most people think about the effects of extreme heat, they naturally consider things like fatigue, headaches, or feeling a bit faint or nauseated. But these symptoms are simply the tip of a melting iceberg: Heat exposure is linked to many things that can damage vital organs, sometimes permanently.

It all starts with thermoregulation, a concept that describes how the body maintains a steady internal (or core) temperature of 98.6 F. Thermoregulation is controlled by a gland in the brain called the hypothalamus, which responds to higher air temperature by signaling the blood vessels to expand and redirect blood, salt, and fluids to the skin in order to cool off through the process of evaporation (sweating).

But is there such a thing as "too hot?"

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