The main purpose of this ongoing blog will be to track planetary extreme, or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉
Main Topic: New Study Indicates a Lower Limit of Human Heat Tolerance
Dear Diary. Human beings are quite adaptable, having settled across all continents with environments from the hot tropics to the bitterly cold Arctic via ingenuity that most other animal species lack. It was my hope that even if average temperatures of the planet punched well above +2.0°C above preindustrial conditions that we would adapt with a large segment of us surviving extreme heat. We might finally learn our environmental lessons in the 22nd century, so we would just be able to adapt to harsh conditions as the planet slowly cools because we have stymied carbon pollution. Well, that might not be in the cards according to a new study.
Evidently the human body is less tolerant of extreme heat than previously thought according to a new study. If true more of us will die and sooner due to climate changing heat than what has been told by experts to policy makers. Here are details from U. Ottawa:
https://www.uottawa.ca/about-us/news-all/new-study-validates-lower-limits-human-heat-tolerance
New study validates lower limits of human heat tolerance
By Bernard Rizk Media Relations Advisor, uOttawa
March 31, 2025
Photo: freepik.com
How much can our bodies adapt to a hotter and more humid planet?
A study from the University of Ottawa’s Human and Environmental Physiology Research Unit (HEPRU)north_eastexternal link has confirmed that the limits for human thermoregulation—our ability to maintain a stable body temperature in extreme heat—are lower than previously thought.
This research, led by Dr. Robert D. Meadenorth_eastexternal link, former Senior Postdoctoral Fellow and Dr. Glen Kenny, Director of HEPRUnorth_eastexternal link and professor of physiology at uOttawa’s Faculty of Health Sciences, highlights the urgent need to address the impacts of climate change on human health.
The study found that many regions may soon experience heat and humidity levels that exceed the safe limits for human survival. “Our research provided important data supporting recent suggestions that the conditions under which humans can effectively regulate their body temperature are actually much lower than earlier models suggested,” states Kenny. “This is critical information as we face increasing global temperatures.”
Health Sciences
“The conditions under which humans can effectively regulate their body temperature are actually much lower than earlier models suggested”
Glen Kenny
— Director of HEPRU and professor of physiology at uOttawa’s Faculty of Health Sciences
Utilizing a widely used technique known as thermal-step protocols, Meade and his team exposed 12 volunteers to various heat and humidity conditions to identify the point at which thermoregulation becomes impossible. What made this study different, was that participants returned to the laboratory for a daylong exposure to conditions just above their estimated limit for thermoregulation. Participants were subjected to extreme conditions, 42°C with 57% humidity, representing a humidex of approximately 62°C. “The results were clear. The participants’ core temperature streamed upwards unabated, and many participants were unable to finish the 9-hour exposure. These data provide the first direct validation of thermal step protocols, which have been used to estimate upper limits for thermoregulation for nearly 50 years”, says Meade.
“Our findings especially timely, given estimated limits for thermoregulation are being increasingly incorporated into large scale climate modellingnorth_eastexternal link” explains Meade. “They also underscore the physiological strain experienced during prolonged exposure to extreme heat, which is becoming more common due to climate change.”
The implications of this research extend beyond academia. As cities prepare for hotter summers, understanding these limits can help guide health policies and public safety measures. “By integrating physiological data with climate models, we hope to better predict and prepare for heat-related health issues,” adds Kenny.
As the world grapples with the realities of climate change, this research aims to spark important conversations about our safety and adaptability in increasingly extreme environments.
For more information, read the study titled “Validating new limits for human thermoregulationnorth_eastexternal link”, published in the Journal PNAS.
Here are more “ETs” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks, as well as any extreme precipitation reports:
Here is More Climate News from Sunday:
(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)