In Kim Stanley Robinson’s climate fiction novel The Ministry for the Future, the story begins during an extreme heat wave in India. Temperatures and humidity, together known as “wet bulb temperature” exceed the levels that the human body can handle and millions of people die.
That’s fiction, but the idea that this could actually happen in the near future is not too far fetched. In 2023, the University of Ottawa got a dozen volunteers to submit to a test to find out the limits of human survival. They were put in a steel chamber where temperatures were raised to 42 degrees Celsius (107 degrees Fahrenheit), and the humidity was gradually increased. After several hours, their internal temperatures increased too, makling it physically impossible for them to cool down through evaporation.
The resulting study was published last week, and confirmed that these dangerous temperatures are much lower than previously believed.
Luckily, here in New York the Department of Environmental Conservation (DEC) and the NYS Energy Research & Development Authority (NYSERDA) have put together an extreme heat action plan to make sure all New York communities have the resources and adaptation strategies they need to optimize citizen health and well-beling.
For most of the past decade, scientists have posited that the highest wet bulb temperatures human could tolerate were in the 35 degree Celsius range (around 95 degrees Fahrenheit), but in recent years, research began using actual human test subjects, and the results were that the maximum temperature is much lower- around 26 degrees Celsius or 79 degrees Fahrenheit. Given the right mix of temperature and humidity, many places could experience wet bulb temperatures as early as 2045, when global temperatures are believed to rise 2 degrees Celsius over pre-industrial levels.
The new study also tested people for over 9 hours, bringing the test conditions much closer to an actual heat wave. After 10 hours, in the test conditions, researchers estimated that participants would start to experience heatstroke.
And lower temperatures with high humidity could still be dangerous for people working outside, those who lack access to air conditioning and folks with pre-existing health conditions.
“Any elderly person’s circulatory system isn’t going to be as good at dispersing heat,” said Radley Horton, a professor at the Columbia Climate School. “When the temperatures start to get really extreme, the body has to start making some difficult choices,” he said.
Heat can already be deadly under certain conditions, and those conditions will definitely be exacerbated by climate change. Hopefully, studying the combined effects of high heat and humidity can help us better understand what we need to do to mitigate those effects in the not-so-distant future.
You can read more about this on the Grist.org website here.
