The June that just ended was the Earth’s hottest — ever. And the first week of July saw the trend continue. The surging summer temperatures made me wonder: Just how much heat can the human body stand?

Deaths from heat are pretty common, and as the world heats up, may become more so if we don’t develop a plan for extreme heat days, like the kind of warning system that usually comes before a major hurricane or blizzard. In 2019, approximately 469,000 people worldwide died from overheating, according to a paper published in 2021 in The Lancet.

Heat is sometimes called the silent killer, said Ollie Jay, director of the Heat and Health Research Incubator at the University of Sydney. It doesn’t make for dramatic television footage the way tsunamis and tornados and floods do. "People who die are often old, they’re socially isolated, they’re living in low-income settings, they’re often not found for days after they’ve died,” he said. We don’t recognize the dangers.