New research shows that man has certain limits: he cannot cope with the effects of extreme heat combined with a certain level of humidity.
A new interdisciplinary study led by researchers from the Penn State College of Science and the Purdue University College of Sciences has shed light on the potentially devastating impact of extreme heat caused by to climate change.
According to this work published in the Proceedings of the National Academy of Science, if global temperatures increase by at least 1°C compared to current levels , billions of people could be exposed to heat and humidity levels exceeding their tolerance limits.
Experts note that extreme heat waves, combined with high humidity, can cause severe heat waves. Higher humidity can be extremely dangerous because the air cannot absorb the excess humidity, limiting the evaporation of moisture. human body sweat and humidity of certain infrastructure, such as evaporative coolers. In other words, man can no longer naturally cool his body and he then lives in conditions which are no longer favorable to his body. the species.
An example is given by researchers: the limit for a young person in good physical condition is around 31°C A level of 100% humidity, according to work published last year by Penn State researchers. Besides temperature and humidity, the specific threshold for each individual also depends on their level of exertion and other environmental factors, including wind speed and solar radiation.
In the history of humanity, temperatures and humidity have changed. surpassing human limits have not been registered only a limited number of times – and only for a few hours outside. both – in the Middle East and Southeast Asia, according to researchers.
Billions of people at risk of short term
The study modeled warming scenarios ranging from 1°C to 4°C to identify the regions where heat and humidity levels would exceed human tolerance. If warming reaches 2°C, billions of people in India, China and sub-Saharan Africa would face severe climate change. prolonged periods of intolerable heat, mainly in the form of humid heatwaves, making air conditioning and heat mitigation inaccessible for many populations living in low-income countries. low or middle income.
The scenario of +2°C compared to today can correspond to the "pessimistic" of the IPCC to The horizon is 2100, but the trajectory is regularly reassessed with indicators that do not commit to a long period of time. optimism.
À With 3°C of warming, regions such as the east coast and central United States, South America and Australia would experience increased temperatures. Extreme heat of this order is also common, although the United States does not exceed the limits of human tolerance as frequently as other regions.
The researchers highlighted Note that these models do not account for extreme and unusual weather events, such as the 2021 Oregon heat wave or record high temperatures. à London in summer last.
The research emphasizes that governments and policy makers should respond very quickly. "Across the world, official weather adaptation strategies focus only on temperature," Qinquin Kong, who participated in the “But this research shows that moist heat poses a much greater threat than dry heat. Governments and policymakers need to re-evaluate the effectiveness of heat treatment. “We are building heat mitigation strategies to invest in programs that will address the greatest dangers people will face.”
The ;éstudy also emphasizes the fact that countries with Middle-income and low-income earners will be particularly vulnerable, but rich countries will not be spared.