In the summer of 2023, dozens of people entered a steel room at Ottawa University designed to test the survival limits. It is equipped with heart rate screens and temperature investigations, and waited at 42 degrees Celsius, or 107 degrees Fahrenheit, while moisture firmly rose, painting their bodies in sweat and condensation. After several hours, the inner body temperatures began to climb up, as the heat cook it from the outside.
“Few people on this planet have suffered from temperatures like this,” said Robert Meed, a post -PhD researcher at Harvard Public Health Faculty at Harvard University, who led the study. “Imagine the condensation of moisture on the skin like a cup of water on a hot day. This is what the weather was hot, compared to the degree of skin.”
Their experience tested the body’s ability to overcome the intense heat by exposing the participants to temperatures that could no longer calm themselves. they TicketAnd that was published last week in the Journal of Science PNAS, confirmed that this dangerous threshold is much lower than that of scientists previously believed: the so -called wet lamp temperature, which represents heat and humidity, from 26 to 31 degrees Celsius.
Mid said that scientists call this point a point of “unreasonable” heat stress, “because the body cannot compensate for the thermal lamb placed on it.” “With climate heat heat waves, there was a lot of attention in defining these upper limits.”
When studying the health risks of heat, scientists often refer to the temperatures of the wet lamp because moisture in the air can make the heat waves more common by preventing the body’s ability to sweat in the heat effectively.
For more than a decade, it was widely believed that the maximum temperature of the wet lamp that the bodies could deal with was 35 degrees c It is unlikely to become common until global warming has reached 7 amazing degrees on pre -industrial temperatures.
Until 2022, a group of researchers did not test this limit with human issues, and they found that things may become dangerous in a much closer, at the temperatures of the wet lamp as low like 26 ° C This threshold means that the vast areas of the planet can become risky to live with two degrees of global warming – which can be accessed Early in 2045 If greenhouse gas emissions are not reduced.
“With a warming climate, we expect these thresholds to start often.” “The heat waves are larger in size, and they last longer,” said Tony Wolf, Assistant Professor at Georgia University who studies heat stress and participated in a 2022 study.
Other studies, such as Wolf, have tested this lower heat tolerance for two hours. But Wolf says that the latest study is the first to do so over nine hours, closer to what a person may already try during the heat wave. Not only a few participants were able to complete the nine hours while they are exposed to temperatures at the “unreasonable” limit, although researchers estimated that the stroke would happen after 10 hours. At slightly lower temperatures, the participants were on the right path to try a stroke within 35 hours.
“It is very rare to have high temperatures of the wet lamp for more than a day.” “But if you are thinking about what will be the case for a person already exposed to these degrees, this limit still indicates the point where the basic temperature is in this crazy train, flowing and higher.”
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Various factors can make thermal stress more likely in low temperatures, too. Outdoor work, pre -existing health conditions, and lacks access to air conditioning can make moderate heat waves fatal. While I tested the study of the young adults of healthy adults, the wolf research I have found that the elderly suffer from heat stress at lower temperatures.
“The blood circulation system for any elderly person will not be good at the heat dispersion. When the temperatures begin to become extreme, the body should start making some difficult options,” said Radley Horton, a professor at Colombia Climate School, when the temperatures begin to be very extreme.
In February, Horton published a study In nature This has been found that 2 degrees Celsius of warming can make more than a third of the Earth’s lands very hot for those over the age of 60 years – a five -time risk area of five times than it will be for younger adults. The study found that regions with hot and humid climates in particular, such as the Middle East, West Africa and Southeast Asia, will be more difficult. Cities like Karachi, Pakistan can bake under very hot temperatures for older adults by 20 percent of the year.
Research conducted by Pennsylvania State University predicts that maintenance of global warming is under almost two degrees The risk of heat is not widely replaced. But last year, global temperatures increased beyond the predictions of scientists, as it was identified in 2024 as the first year of breaching 1.5 degrees Celsius of warming.
The increasing temperature has already caused serious losses. Between 1999 and 2023, heat death in the United States More than weakness, rises From about 1,000 deaths per year to more than 2000. Over the same time, nearly a quarter of a million people died all over the world. In 2023 alone, More than 47,000 Europeans He died of heat, with countries in the Mediterranean – which heats 20 percent faster than the rest of the planet – the most difficult.
“People are already dying from heat waves now,” said Wolf. “Regardless of what happens to the future climate, it is important to understand, now, what are these thresholds that we start to see a greater danger of disease and death associated with heat?”