People and Community Research

Is the nation prepared for the impact of an ‘extreme heat belt’?

Death Valley-like temperatures above 125 degrees Fahrenheit caused by the climate crisis will affect a large portion of the nation 30 years from now. The way we build must improve to keep people safe, according to a University of Miami School of Architecture professor.
Texas drought

A rancher near Snyder, Texas, surveys his shrinking pond in this file photo from 2011. Photo: The Associated Press


It’s the hottest place on Earth, with the thermometer often reaching 120 degrees Fahrenheit—in the shade. 

But 30 years from now, temperatures synonymous with Death Valley in eastern California will affect millions of people in a corridor of the nation that stretches from Texas and Louisiana all the way to the Great Lakes, according to a new study by the climate research group First Street Foundation. 

Released earlier this week, the report projects that 107 million people living in that area of the United States will experience “extreme heat belt” temperatures—a measure of how hot it feels when relative humidity is combined with the air temperature—above 125 degrees Fahrenheit by 2053. 

Researchers at the Brooklyn, New York-based nonprofit used hyperlocal data to determine the seven hottest days currently for any community. They then calculated what the equivalent would be 30 years from now, finding that a community’s seven hottest days will increase to 18 by 2053. 

Miami-Dade will experience the biggest change in extreme temperatures. The county’s seven hottest days (heat index temperatures at 103 degrees Fahrenheit) will soar to 34 days at that temperature within the next three decades, the report found. 

“That’s directly related to climate change, no question about it,” said Ben Kirtman, professor of atmospheric sciences at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science. 

“The number of 90-plus-degree days is going to steadily increase so that much of the Southeast by 2100 is going to see over 100 days in a row where the temperatures exceed 90 degrees every day,” he pointed out. “That’s quite remarkable. And extreme heat like that, without question, is the No. 1 cause of weather-related fatalities—much more than floods, hurricanes, and lightning.” 

Fortunately, such extreme heat waves can be predicted well in advance, said Kirtman, the architect of the Subseasonal Experiment, or SubX, which combines multiple global forecast models to predict weather conditions three to four weeks in advance. 

But is the nation’s infrastructure, especially in Miami-Dade County, currently adequate to deal with the temperatures that are expected in 2053? Joanna Lombard, a professor in the School of Architecture, whose research centers on design strategies to create healthy neighborhoods, answers questions about the ability of the nation’s built environment to withstand extreme heat. 

Miami-Dade County is projected to see the largest shift in extreme temperatures. Are we built for this? Are our buildings and neighborhoods currently resilient enough to withstand the extreme heat and humidity that will impact much of the nation in the next 30 years?  

I don’t think we are ready for a month of dangerous days here in Miami-Dade. Conditions vary greatly across blocks and neighborhoods. So, streets that are closer to the coast, oriented along the axis of our prevailing southeasterly breezes, and lined with trees are going to be less miserable than streets with little breeze, no trees, and unrelenting radiant heat. At this moment, though, we aren’t built for cooling. And that’s why the first solution is making it possible for everyone to have access to air-conditioning, which is both architectural—in that effective AC needs to be installed and/or maintained, and buildings need to be made more heat resistant—and operational. Energy costs of air-conditioning need to be affordable. Many cities are also discussing cooling centers where people can go during heat events, and in Miami-Dade, our chief heat officer, Jane Gilbert, is working on this, too. That can be an interim step in the way that emergency shelters operate during a storm. But ultimately, people need to be safe where they live.

What must happen to prepare us for this? How do we need to build differently? 

There are overall strategies to reduce heat levels through increasing greenspace, decreasing pavement, cooling roofs through green roofs, or more simply, white roofs. And then, within each neighborhood, there might be more specific opportunities to cool dwellings, which could mean adding porches or awnings to shade exterior walls or increasing canopy trees and protecting the west faces of buildings from direct sun. For new buildings, it is important to orient the largest facades to the north and south with limited exposure on the east and especially the west, positioning walls to enhance breezes and contributing to the tree canopy in every way possible. Right now, with buildings lacking in shade, greenery, and air flow, we start with a hot box even before the outside temperature reaches the danger zone. If we built to be cool without air-conditioning, then when we reach the danger zones, AC doesn’t have to work as hard to get us to habitable. 

What strategies can be implemented beyond environmental adaptations? 

We can adjust our social environment. We need to protect outdoor workers, reconsider hours of activity, and become more attentive to adjusting our behavior to the climate. The increasing levels of heat will be so insistent that we won’t have a choice in the future. So, planning now can provide a measure of stability.