The projections are part of First Street Foundation’s new, peer-reviewed extreme heat model, which shows that most of the country will have upticks in the number of days with heat index temperatures above 100 degrees over the next 30 years as a result of climate change.
The heat index represents what a temperature feels like to the human body when humidity and air temperature are combined. It is commonly referred to as the “feels like” temperature.
“Everybody is affected by increasing heat, whether it be absolute increases in dangerous days or it’s just a local hot day,” said First Street Foundation’s chief research officer, Jeremy Porter, a professor and the director of quantitative methods in social sciences at the City University of New York.
It has already been a sweltering summer for much of the U.S. and Europe. The National Oceanographic and Atmospheric Administration’s latest monthly climate report, published Aug. 8, found that last month was the country’s third-hottest July since record-keeping began nearly 130 years ago.
As humans continue to pump heat-trapping greenhouse gases into the atmosphere, temperatures around the world are rising, which increases both the frequency of extreme heat events and their severity.
Researchers at First Street used their model to create an online tool called Risk Factor to give people hyperlocal snapshots of how their property is affected by extreme temperatures and what could change over the next three decades. The organization previously created similar resources to evaluate specific addresses’ risks from wildfires and flooding.
The new model uses high-resolution measurements of land surface temperatures and incorporates the effects of canopy cover, proximity to water and other factors that determine local temperature variability. Future heat risk is then calculated using different forecast scenarios for greenhouse gas emissions in the decades to come.
The researchers looked at the seven hottest days expected for any property this year and calculated what the equivalent could be in 30 years. Across the country, they found that, on average, a community’s seven hottest days are projected to become the location’s 18 hottest days by 2053.
The most pronounced shift was found in Miami-Dade County, Porter said, where the area’s seven hottest days, with heat index temperatures at 103 degrees, are projected to increase to 34 days at that temperature in 30 years.