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Cities are trying to understand how concrete stores heat — with interesting results

JUANA SUMMERS, HOST:

Global warming is driven primarily by burning fossil fuels, and it pushed temperatures so high last year that scientists were astounded. In fact, last year was the hottest on record. Cities are now trying to prepare for how to handle increasingly hot temperatures. As Britny Cordera, with member station KGOU reports, Oklahoma City is turning to heat mapping for clues.

BRITNY CORDERA, BYLINE: Hongwan Li attaches two devices to the windows of her car.

HONGWAN LI: This one's the particle sensor.

CORDERA: She and her daughter are helping researchers on this rainy August day to take air quality and temperature readings around Oklahoma City. Li researches air quality at the University of Oklahoma. Last year, Oklahoma City joined over a dozen cities in a national heat mapping project. Community members just like Li helped record data that could be used to help cities understand the impacts of extreme heat.

LI: We want to take a deeper look for the heat stress, like in the communities. The community-based is the most appropriate way to understand the heat stress better.

CORDERA: The data collected last August showed downtown Oklahoma City was 15 degrees hotter than the suburbs. I'm walking through my neighborhood near downtown. I was surprised to find out that this area, with its giant sycamore trees, got pretty warm last summer. Sarah Terry-Cobo led last year's efforts to map heat. She works in the city's Office of Sustainability. Terry-Cobo says my neighborhood - Mesta Park - was one of the hottest areas in Oklahoma City.

SARAH TERRY-COBO: A really treed neighborhood like Mesta Park is still pretty hot compared to some of these other neighborhoods that we were expecting to be very hot.

CORDERA: Trees don't always provide enough cooling. That's because heat gets trapped in roofs, roads and sidewalks. It creates what's called the urban heat island effect.

(SOUNDBITE OF BIRD CHIRPING)

CORDERA: Terry-Cobo and I walked around downtown last summer to capture thermal images on her phone.

TERRY-COBO: Oh, look at this. I just love the contrast. With the sidewalk at 92 degrees, 93 degrees. And then this big ole - maybe it's a spruce, I'm not sure - at 85.

CORDERA: She was surprised by how different the temperatures were between the sidewalk and the prairie habitat at Myriad Botanical Gardens. Her camera reveals the cooler temperatures in blue and purple.

TERRY-COBO: So what we're seeing right now in the Myriad Gardens is a great example of a potential cooling strategy for urban heat islands.

CORDERA: Cooling strategies are what can come from understanding the hottest parts of urban areas. Last summer, 14 cities, including Oklahoma City, worked with NOAA and citizen scientists to map where the urban heat islands are. Joey Williams is with CAPA Heat Watch. The program provides the equipment for the urban heat island project and the results. Williams says the project started in 2017 and helped cities make plans for how to address extreme heat.

JOEY WILLIAMS: As the threat of heat continues to rise and people have become more aware that heat is an issue and life-threatening and it affects different people differently, having this just kind of awareness can be a lifesaver.

CORDERA: Sustainability offices in cities are taking the results from last summer's mapping to develop ways to adapt to heat. Kansas City, Mo., has already done this, using its past data to show where it lacked tree canopy. Andy Savastino, with the city's sustainability office, says the heat mapping helped inform a new policy.

ANDY SAVASTINO: Anytime a developer wants to come in, particularly into areas where you've got old forest growth, our tree preservation ordinance - which we never had one before - now applies so that there is some requirement for developers to replace some percentage of what they take down.

CORDERA: Oklahoma City's heat mapping campaign found the city needs more trees and less parking lots to help cool off neighborhoods. And the city is working on a guidebook this year to help leaders figure out the best ways to adapt to extreme heat, like changing parking zoning laws or restoring natural habitat.

For NPR News, I'm Britny Cordera in Oklahoma City. Transcript provided by NPR, Copyright NPR.

Corrected: January 19, 2024 at 12:00 AM EST
A previous byline misspelled Britny Cordera's first name as Britney.
Britny Cordera