Daring to turn heat up on the limits of human endurance

Explorer braves extreme terrains to study impact of rising temperatures

LONDON — What Christian Clot remembers most vividly from his days in Iran’s boiling Dasht-e Lut Desert was having to stay completely still for 12 hours a day — or die.

“It was so hot I had to lie down behind some rocks between 8 am and 8 pm. Staying in a tent was too dangerous as it would have instantly overheated,” he said.

Clot, a French-Swiss explorer, is testing the limits of human endurance, including to worsening temperature extremes.

In the Iranian desert and on three other 30-day expeditions alone in the world’s harshest climates, he has explored what impacts extreme weather might have on people, both physically and mentally.

“Most studies on the human body have been done in labs rather than in real settings,” he said.

“I wanted to experience what you can’t find in scientific journals.”

If planet-warming emissions continue to rise at their current pace, three in four people in the world will face deadly heat by the turn of the century, according to a study published in the journal Nature Climate Change in June.

Emily Y.Y. Chan, a professor of public health at the Chinese University of Hong Kong, expects heat waves to become not just more frequent but also longer by the end of the century.

That could lead to a range of worsening health problems, including malnutrition.

For his experiment with heat, Clot chose Iran’s Dasht-e Lut Desert, where the daytime temperature can approach 60 C.

“I knew I could die within hours of exposure to such high temperatures,” he said.

Each day, Clot collected data, including his heart rate and body temperature, and carried out tests to assess the heat’s impact on his mental abilities, including his decision-making and memory.

Although his scientific team is still analyzing the results, Clot said the biggest challenge was extreme physical and mental tiredness.

“Every movement I made was slower and demanded more effort,” he said. “I was conscious of the threat surrounding me but found it extremely challenging to stay attentive at all times.”

Another study, published in the journal Science Advances in June, found that expected future increases in temperatures globally could result in a “drastic” hike in deaths in developing countries.

Separately, Chan and her team identified temperature thresholds beyond which deaths and hospital admission rates start to rise.

“We found that daily mortality increases by 1.8 percent for every degree above the threshold of 28.2 C, while daily hospitalization — for respiratory and infectious diseases, for example — increases by 4.5 percent for every degree above the threshold of 29 degrees Celsius,” she said.

Chan worries that governments and the public are illprepared to deal with rising temperatures because of a general lack of awareness about how heat can impact people’s health.

Clot plans to repeat his desert-heat expedition next year, this time with a group of 10 men and 10 women.

The aim is to assess how climate extremes affect group dynamics, something he hopes will help people “better adapt to weather extremes and other environmental challenges”.

I knew I could die within hours of exposure to such high temperatures.”

Christian Clot,