Research from the University of Ottawa underscores the critical need for climate action as it reveals humans can endure less heat than earlier believed. This study highlights the pressing health risks in a warming world.
A new study from the University of Ottawa’s Human and Environmental Physiology Research Unit (HEPRU) has revealed that humans’ ability to maintain stable body temperatures in extreme heat — known as thermoregulation — is more limited than previously thought. This revelation underscores the critical urgency of addressing the impacts of climate change on human health.
Published in the journal PNAS and led by Robert D. Meade, a former senior postdoctoral fellow, and Glen Kenny, HEPRU director and a professor of physiology, the study found that many regions might soon face heat and humidity levels that surpass 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,” Kenny said in a news release. “This is critical information as we face increasing global temperatures.”
Utilizing a widely accepted method known as thermal-step protocols, Meade and his team exposed 12 volunteers to various heat and humidity conditions to pinpoint the point at which thermoregulation becomes impossible. The participants faced extreme conditions at 42 degrees Celsius with 57% humidity, equating to a humidex of approximately 62 degrees Celsius.
What set this study apart was the participants’ return for a daylong exposure to conditions just above their estimated limit for thermoregulation.
“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,” added Meade.
“Our findings [are] especially timely, given estimated limits for thermoregulation are being increasingly incorporated into large scale climate modeling,” Meade continued. “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 study extend far beyond academic circles. As cities prepare for increasingly hot summers, understanding these limits can help shape 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,” added Kenny.
As global temperatures rise, this research aims to catalyze crucial conversations about human safety and adaptability in increasingly extreme environments.
Source: University of Ottawa