- More than 94% of the nation could see the hottest days double
- By 2053, more than 105 million people could be exposed to heat indices above 125 degrees
- The middle of the United States becomes a heat belt
A new report examines how dangerously hot the temperatures are could increase over the next 30 years and reveals a bleak outlook for much of the country, especially a large part of the central United States where residents are unaccustomed to extreme heat.
South Florida is forecast to see the largest increases in the number of hottest days. a new thermal model and a new evaluation by the First Street Foundation. But the report shows even some of the northernmost counties in the country cannot escape the effects of global warming.
“Extreme heat exposure is increasing across the country,” said Jeremy Porter, research director for First Street, a Brooklyn-based research and technology group.
The foundation looked at average heat index temperatures – what it feels like to be outdoors based on temperature and humidity – during the seven hottest days of the year.
Considering how climate change could increase the frequencythe length and intensity of dangerously hot days over 30 years, the report found that 94% of counties nationwide could see those days double.
Next year, more than 8.1 million residents in 50 counties could experience at least one day with a heat index above 125 degrees. By 2053, this could reach more than 105 million inhabitants spread over a third of the country.
The findings build on previous heat studies, raise questions about how people will handle the heat and offer further evidence that communities should already be preparing, experts said.
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The new report comes just as the country is experiencing a succession of heat waves and broken records.
July was the third hottest on record in the United States, and the average temperature of 76.4 degrees was nearly 3 degrees above normal, the National Oceanographic and Atmospheric Administration announced last week. . Texas had its hottest July on record, while Oregon just had its hottest July 4th.
First Street’s 2053 projections are very different depending on where you are.
- Today, temperatures are 103°C or higher for the seven hottest days of the year in Miami-Dade County, Florida. This could reach 34 days by 2053.
- On Martha’s Vineyard in Massachusetts, only three days a year resemble 90 degrees, but that number could quadruple to a dozen.
- High in the Rocky Mountains in northern Montana, Glacier National Park could see three days a year when the temperature is around 90 degrees or higher.
Learning days with a heat index of 100 or more could more than quadruple in Miami didn’t surprise Miami Beach native Steve Keats much.
“Nature is after us – heat and rising sea levels,” Keats said.
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What is the First Street report and where can you find it?
A peer-reviewed assessment and extreme heat model, this is the latest in a series from First Street and its partners examining warming-related risks in communities across the lower 48 states, including floodsthe sea level rises and forest fire. The foundation and its partners gathered federal weather records, property records, satellite information and other data for its model, using interim global climate projections. He also considered tree cover, paved surfaces and proximity to water.
The public can find the tool, Heat Factor, at RiskFactor.com and examine future real estate projections and trends over the past 30 years.
Showing past trends should help build confidence in the projections, Porter said, because people will see that there are more hot days today and a higher likelihood of heat waves and dangerously hot days.
A heat belt emerges
By 2053, residents of 430 counties in 16 states could see the number of days with their current hottest temperatures more than triple, according to First Street modeling.
Outside of Florida and the Southwest, the counties and states expected to see the largest increases are concentrated in an arc north of Texas and Louisiana across the Gulf of Mexico north of Missouri and Illinois. , and include western Kentucky and Tennessee.
First Street has dubbed this area “an emerging heat belt,” due to its risk of exposure to extreme heat index temperatures of over 125 degrees, Porter said. The low-lying region between the Rockies and Appalachia is “almost a bowl of high humidity, and it interacts with rising temperatures.”
Unlike coastal areas, the region does not have sea breezes to cool the heat.
A 2021 survey by USA TODAY found that the region has also seen an increase in intense rainfall from the warming Gulf of Mexico.
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The top five metropolitan areas with the most neighborhoods that could experience extremely dangerous heat days are St. Louis and Kansas City, Missouri; Memphis, TN; Tulsa, Oklahoma; and Chicago, according to the First Street report.
Unlike residents of southern states, residents of states like Missouri and Illinois may be less prepared, less likely to have air conditioners, and more likely to experience extreme heat.
Where are the other hotspots?
- Looking at percentage increases, two counties at the top of the Texas Panhandle — Hartley and Oldham — could see the biggest increase in days above a 100-degree index, a 600% increase. North Carolina, West Virginia and Colorado counties were also in this top 20 list.
- Colder counties show up more often when looking at the percentage increase in days that are warmer than 90 degrees. Instead of seeing one day a year with a temperature that feels like 90 degrees, Snohomish County, Washington, just north of Seattle, could see five such days a year, a 400% increase.
- The west coast of the country has the highest probability of consecutive locally warm days, but feels the greatest cooling effect from the ocean.
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What do the projections mean?
The increase in potential heat waves and warmer nights is “really concerning,” said Gabriel Filippelli, executive director of Indiana University’s Environmental Resilience Institute.
People tend to endure one or two days of hot weather, Filippelli said, but when it lasts three or four days, human body systems begin to break down, especially in children, the elderly and people in the low-income communities.
When heat concentrates in urban areashe said temperatures don’t drop at night and people get little to no relief.
This can create significant health issues, said Duke University climate health scientist Ashley Ward. “When nighttime temperatures remain high, what we find is that the body has no chance of recovering from daytime heat exposure.”
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Structural changes are needed now to prepare, she said.
Meanwhile, in South Florida, Keats, a shipping industry executive, made his own adjustments to avoid heat stress.
“I don’t go out much before 4 p.m. unless I’m in or on the water,” he said. “I also nap on the weekends…because that’s what it takes to adapt to the heat.”
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Dinah Voyles Pulver covers climate and environmental issues for USA TODAY. She can be reached at dpulver@gannett.com or @dinahvp on Twitter.