Philip Kreycik should have survived his race.
In the summer of 2021, this 37-year-old ultramarathoner used an app to map an approximately 8-mile loop through Pleasanton Ridge Regional Park in California, a vast park with many trails.
On the morning of July 10, as temperatures approached 90 degrees, Kreycik set off from his car, leaving his phone and water locked inside. He started at a lightning pace, covering the first 5 miles, each in under 6 minutes.
Police at Pleasanton Ridge in California on August 3, 2021, after a volunteer found the body of Philip Kreycik under a tree. Santiago Mejia/San Francisco Chronicle/Getty Images
Then things went wrong. His smartwatch's GPS data showed his pace slowing dramatically. He veered off the trail. His steps became erratic. By this time, temperatures had exceeded 100 degrees Fahrenheit.
When Kreycik didn’t show up for a family lunch, his wife contacted the police.
It took more than three weeks to find his body. An autopsy showed no signs of trauma. Police confirmed that Kreycik likely experienced a heat-related medical emergency.
Tragically, this incident is not unique; extreme heat is making ordinary activities deadly.
People are dying in midday sun while walking, during family hikes in national parks, at outdoor concerts, and even in their homes without air conditioning. During this year's Hajj pilgrimage, around 1,300 people died as temperatures in Mecca surpassed 120 degrees Fahrenheit.
Heat is the deadliest form of extreme weather, and the human-induced climate crisis is making heatwaves more severe and prolonged. Coupled with humidity, conditions in some places are approaching the limits of human survivability – our bodies simply can't adapt.
"We've essentially weaponized summer," said Matthew Huber, a climate professor at Purdue University.
In the extreme heat, Kreycik had almost everything going for him: he was exceptionally fit, relatively young, and an experienced runner. Despite this, he fell victim to the heat, highlighting that no one is immune, not even elite athletes.
Scientists are still working to understand the various ways heat attacks the body. One method is through environmental chambers where they can test human responses to a wide range of temperatures and humidity levels.
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