We know the planet is getting hotter, but some of the grim details about what exactly that means for humanity remain a mystery.
Researchers are racing to peer into the not-too-distant future of the climate crisis to better prepare us for the worst-case scenarios to come. A new climate study published on Tuesday found that by 2040, overwhelming urban heat and spiking temperatures in the U.S. could double the number of people hospitalized with heat-related illnesses (HRIs). Using advanced modeling, the researchers predicted that HRIs could result in 217,000 hospitalizations by 2040 in a low-emissions scenario and as many as 237,000 if emissions soar. In both scenarios, heat-related hospitalizations would double.
According to the new paper, published by Portland State University professor Vivek Shandas and Stephan Brown of the climate adaptation group CAPA Strategies, the life-threatening risks associated with extreme heat won’t affect Americans evenly—and the sooner we can predict those differences, the better we can mitigate the danger.
“Despite growing concerns about the negative health impacts from extreme heat, we still know relatively little about how, and to what extent, increases in temperatures, particularly in cities where the majority of humans live and where the built environment amplifies temperatures, interact with co-mediating factors such as demographics, health status, and cooling options to drive [heat-related illnesses],” the authors wrote.
The researchers chose 53 major metro areas in the U.S. for their statistical sample, grouping them by geographic region to see how populations across different parts of the country will be impacted by extreme heat. That created nine regions for modeling purposes: the Northeast, the Northern Rockies and Plains, the Northwest, the Ohio Valley, the South, the Southeast, the Southwest, the Upper Midwest, and the West. Across those regions, heat, humidity, and weather patterns vary widely, as do population center demographics.
The researchers also modeled how health outcomes on a warming planet will reflect people of different races based on where they live in the country. They found that heat-related illness will unevenly impact different racial groups, but those disparities could be very pronounced in some regions and much less dramatic in others.
“In terms of magnitude of disparities across the four race groups, the Northeast, Ohio Valley, South, Southwest and, to a lesser extent, West regions exhibited the largest disparities, with the highest risk group experiencing [heat-related illnesses] at a rate roughly 12 times (Ohio Valley) to over 57 times (Southwest) that of the lowest risk group,” the authors wrote. “While these regional differences are notable, White populations, apart from the Upper Midwest, have consistently had among the lowest HRI rates across regions and over time.”
Extreme heat will take an uneven toll
Granular predictions about how HRIs will be distributed around the country can shape interventions now, from the way that cities are designed to how tax dollars are put to use in different neighborhoods. “Such models can align specific interventions that address community vulnerabilities to extreme heat while improving the calibration, coordination, and timing of regional responses,” the study’s authors wrote.
Other work from Shandas explores the uneven ways that people will be impacted by extreme heat, even within the same city. During a record-setting heat wave in 2021 in the Pacific Northwest, Shandas drew attention to those disparities by demonstrating how one neighborhood east of downtown Portland, Oregon, was 25 degrees hotter than more affluent areas with a robust urban canopy of trees and greenery to cool things off.
“The way we’ve gone about building our city and the design of the roads, the buildings, the amount of green space—that combined with people who often don’t have easy ways to cool off, that comes together to increase the likelihood of deaths,” Shandas told Portland’s Willamette Week in an interview.
Unfortunately, around the country, urban neighborhoods with the hottest temperatures are losing their trees and green spaces at a faster rate than their cooler counterparts, according to another recent study from Shandas.
