Heat Waves That Threaten Lives Will Be Common by 2100

FRIDAY, Aug. 26, 2022 (HealthDay News) -- Life-threatening heat waves will become more common by the end of this century, according to a new study.

A “dangerous” heat index — what the temperature feels like when humidity and air temperature are combined — is defined by the National Weather Service (NWS) as 103 degrees Fahrenheit. NWS defines “extremely dangerous” as 124 degrees F – unsafe to humans for any amount of time.

Crossing the “dangerous” threshold will be three to 10 times more common by 2100 in the United States, even if countries manage to meet the Paris Agreement goal of limiting global warming to just 2 degrees Celsius (or 3.6 F), researchers report.

And in a worst-case scenario where emissions remain unchecked, “extremely dangerous” conditions could become common in lands closer to the equator, the study warns.

“The number of days with dangerous levels of heat in the mid-latitudes — including the southeastern and central U.S. — will more than double by 2050,” said co-researcher David Battisti, a professor of atmospheric sciences at the University of Washington in Seattle.

“Even for the very low-end estimates of carbon emissions and climate response, by 2100 much of the tropics will experience ‘dangerous’ levels of heat stress for nearly half the year,” Battisti said in a university news release.

For this study, the researchers used a probability-based method to predict the likely range of future carbon emissions and their effect on global temperatures and weather patterns.

The projections included estimates of population increase, economic growth, and carbon emission levels based on economic activity.

“It’s extremely frightening to think what would happen if 30 to 40 days a year were exceeding the extremely dangerous threshold,” said lead researcher Lucas Vargas Zeppetello. He's a postdoctoral researcher at Harvard University.

“These are frightening scenarios that we still have the capacity to prevent,” he continued. “This study shows you the abyss, but it also shows you that we have some agency to prevent these scenarios from happening.”

The study was published online Aug. 25 in the journal Communications Earth & Environment.

More information

The Natural Resources Defense Council has more on global warming.

SOURCE: University of Washington, news release, Aug. 25, 2022