The worsening heat and humidity background caused by climate change will deliver an extremely dangerous heat index for much of the United States over the next 30 years, increasing both, according to a new study published Monday. intensity and frequency of the hottest days of the year, according to a new study published Monday.
Temperatures above the threshold classified as “extremely hazardous” by the National Weather Service, when the heat index is more than 125 degrees Fahrenheit, are expected to affect about 8 million people in the US this year. But by 2053, 13 times as many people – 107 million people – will experience that extreme heat, according to research by the First Street Foundation climate research group.
“The results indicate that rates of extreme heat are increasing across the country, both in absolute and relative terms,” the study states.
The nonprofit’s research shows temperatures will rise in some areas more than others, including the so-called “extreme heat belt,” which stretches from Texas all the way to the Great Lakes.
More than 100 million Americans in the region will experience temperatures above 125 degrees (52 degrees Celsius) during the hottest period of the year, more than 10 times the currently projected number.
Using a peer-reviewed heat extreme model, the First Street Foundation used property-level data to find the seven hottest days in the current year and compare that to the equivalent in 30 years. On average, the seven hottest days will increase to 18 days by 2053, the researchers found.
But in the southern half of the country, the number of hottest days will increase to about 30 – meaning the hottest week of the year will become the hottest month in the 2050s, according to the study.
Florida’s Miami-Dade County will see the biggest change in extreme temperatures, where the 7 hottest days of the year in 2023 (103 degrees heat index) will occur on 34 days in 2053. Other locations in Florida and along the Gulf Coast are likely to experience more than 30 days of heat index above 100 degrees by 2053.
Nationally, the number of counties that are expected to hit a heat index of 125 degrees at least once a year will increase more than 20-fold from 50 in 2023 to 1,023 in 2053, according to the study.
According to the study, the probability of localized heatwaves – defined as higher than normal temperatures for three consecutive days – would also increase nationally, but highest along the West Coast.
“Interestingly, exposure to local consecutive hot days was most likely to occur in the West Coast states, while the Midwest, Southeast, and East Coast states were most at risk of heat exposure. extremely dangerous, meaning that virtually the entire country could see increased research showing the risks associated with heat exposure.
The study also identified projections of change for each US state.
