Where is it hottest in the Triangle? Researchers set out to map urban heat islands.
On a hot, cloudless day this June or July, a fleet of volunteers will drive around Raleigh and Durham with sensors mounted to their cars, capturing data about which places are warmer than others.
These volunteers will be part of an effort to map urban heat islands across the two cities. Urban heat islands are typically created in places where there are more roofs, asphalt and concrete that retain the sun’s hot rays more than plants and trees.
“There can be temperature differences neighborhood by neighborhood upward of 19 or 20 degrees potentially, so one big outcome of this is going to be better understanding of how heat is felt or expressed across the Raleigh-Durham area,” said Max Cawley, the program director of the Museum of Life and Science, the campaign’s lead organization.
The project in Durham and Raleigh is one of 11 selected by the National Integrated Heat Health Information System this summer in partnership with CAPA Strategies. Volunteers will bike or drive around specific parts of the city with the sensors mounted to their cars and bikes, measuring the humidity and temperature each second. A team from CAPA will then use that information and satellite measurements to create a map showing heat islands across the region, which is expected to be available this fall.
Part of the project’s aim is to measure inequities, with the research team anticipating that hotter areas will likely overlap with historical red lining, low income and other inequities.
“Extreme heat is not only a climate phenomena,” Cawley said. “Extreme heat is also a racial justice issue, it’s also an economic justice issue, it’s a public health issue and we are hopeful and anticipate that this project will help inform better decision-making and policy.”
Nationwide, people of color and those who are living far below the poverty line are more likely to live near urban heat islands, according to a forthcoming paper co-authored by Angel Hsu, a UNC Chapel Hill climate scientist. The paper looked at every urban area in the country, 175 in total, and used census tract-level demographic and satellite data to measure who is more likely to live in hotter places.
In 97% of those cities, people of color had higher exposure to urban heat islands than white people. And in 70%, people living below the poverty line had higher exposure than people whose incomes were more than twice the poverty line.
“These patterns are really widespread in nearly every U.S. city,” Hsu said in an interview with The News & Observer.
Existing heat risk
The NC Climate Science Report, released last summer, found that continued growth is “very likely” to exacerbate the state’s urban heat island effect.
“These hotter areas tend to line up with low-income communities or communities of color that historically have been red-lined and there’s a lot of systemic racism inherent in all of this,” said Kathie Dello, North Carolina’s state climatologist and one of the authors of the report.
The state climate office will work with the National Weather Service’s Raleigh office to identify the day this summer when the data will be collected.
Between May 1 and September 30, 2020, the N.C. Department of Health and Human Services reported 3,009 visits to emergency rooms for heat-related illness statewide.
Men accounted for nearly 75% of those visits; people between the ages of 25 and 64 about two-thirds. Emergency room visits were concentrated in the Piedmont (48%) and coastal (47%) regions.
Citizen science
To be successful, organizers will need 200 to 250 volunteers to take the sensors across the city on the day scientists choose. Volunteers will take sensors out in the morning, afternoon and early evening.
Having volunteers collect the data, Dello said, could help the public more easily grasp the differences that are being felt across the region.
“When communities get involved in research in their communities, that’s always great because they have kind of a stake in the game and are perhaps more likely to trust what comes out of it,” Dello said.
Chris Goforth, the head of citizen science at the N.C. Museum of Natural Sciences, will help recruit volunteers. That effort will start with virtual sessions in late May explaining urban heat islands, their impacts and why taking measurements could be important.
Citizen science projects like the heat mapping effort involve people who do not have formal scientific training. They’re popular, Goforth said, because people are able to feel like they are making a difference.
“They’re able to create the knowledge themselves,” Goforth said.
Once it is mapped, the heat information will be made public. Other cities have included those maps in climate resilience plans or to convert public property into green space.
Cawley and other organizers hope people will be able to take the local maps and use them to help shape planning decisions, but also potentially to set up more robust energy affordability programs and heat warning systems.
“Planting more trees, (considering) impervious surfaces, all of that stuff is really important and is going to play an important role in how cities stop the urban heat island effect,” Cawley said, “but so is protecting the most vulnerable people in those communities.”
This story was originally published April 26, 2021 at 8:03 AM.