A new research study published on Monday warns that billions of people, particularly in major cities like Delhi and Shanghai, could struggle to survive in periods of deadly, humid heat within this century as global temperatures rise. The report highlights that potentially lethal combinations of heat and humidity may even spread to areas such as the U.S. Midwest under higher warming scenarios.
The study, co-authored by Matthew Huber of Purdue University, builds upon past research on the threshold at which heat and humidity combine to push the human body beyond its limits without shade or help from technologies like air conditioning. It reveals that around 750 million people could experience one week per year of potentially deadly humid heat if temperatures rise 2 degrees Celsius above preindustrial levels. If warming reaches 3 degrees Celsius, more than 1.5 billion people would face such a threat.
The current policies put the world on track for 2.8 degrees Celsius of warming by the year 2100, as stated in the 2022 United Nations Emissions Gap report. The study also finds that major cities like Lagos and Chicago would face the risk of dangerous humid heat, indicating that it is spreading to places that were not previously considered at risk, including South America and Australia. At 4 degrees Celsius of warming, Hodeidah, Yemen, would experience around 300 days per year of potentially unsurvivable humid heat.
To track moist heat, scientists use a measurement called “wet-bulb” temperature, which is obtained by covering a thermometer with a water-soaked cloth. The study refers to a landmark 2010 study by Huber, in which a wet-bulb temperature of 35 degrees Celsius persisting for six or more hours was proposed as the conservative limit for the human body. This study found that people were likely to succumb to heat stress beyond this limit. The researchers of the current study applied this lower limit to various future climate warming scenarios ranging from 1.5 to 4 degrees Celsius.
Atmospheric scientist Jane Baldwin of the University of California Irvine, who was not involved in the research, referred to this lower limit as a critical benchmark for future studies. She acknowledged that the study paints a grimmer picture than the previous 35 degrees Celsius limit proposed by Huber.
This research adds to the growing concern about dangerous wet-bulb temperatures. Another study published last month in Sciences Advances also reached a similar conclusion, using the wet-bulb threshold alongside weather station data and climate models. It emphasized that the geographic range and frequency of dangerous humid heat will increase rapidly under even moderate global warming.
Overall, the findings of the research highlight the urgent need for action to mitigate global warming and protect the world’s population from the potentially deadly effects of rising temperatures and humidity.
(Reporting by Gloria Dickie in London; Editing by Andrew Heavens)
Credit: The Star : News Feed
