HeatwavesDeadly heatwaves on the rise

Seventy-four percent of the world’s population will be exposed to deadly heatwaves by 2100 if carbon gas emissions continue to rise at current rates, according to a study published in Nature Climate Change. Even if emissions are aggressively reduced, the percent of the world’s human population affected is expected to reach 48 percent.

“We are running out of choices for the future,” said Camilo Mora, associate professor of geography in the College of Social Sciences at the University of Hawaii at Manoa and lead author of the study. “For heatwaves, our options are now between bad or terrible. Many people around the world are already paying the ultimate price of heatwaves, and while models suggest that this is likely to continue, it could be much worse if emissions are not considerably reduced. The human body can only function within a narrow range of core body temperatures around 37^oC. Heatwaves pose a considerable risk to human life because hot weather, aggravated with high humidity, can raise body temperature, leading to life threatening conditions.”

University of Hawaii at Manoa says that a team of researchers lead by Mora conducted an extensive review and found over 1,900 cases of locations worldwide where high ambient temperatures have killed people since 1980. By analyzing the climatic conditions of 783 lethal heat episodes for which dates were obtained, researchers identified a threshold beyond which temperatures and humidities become deadly. The area of the planet where such a threshold is crossed for twenty or more days per year has been increasing and is projected to grow even with dramatic cuts in greenhouse gas emissions. Currently, about 30% of the world’s human population is exposed to such deadly conditions each year.