New Research Finds Limited-Resource, “Redlined” Communities of Color Disproportionally Impacted by Extreme Heat
Science Museum of Virginia Collaborates on Study that Explores Link Between New Deal-Era Neighborhood Ranking System and Susceptibility to Climate Change
Building on data collected during the urban heat island campaigns, researchers have found a link between the New Deal-era neighborhood ranking system called redlining and hotter surface temperatures. New information published in the journal Climate found formerly redlined neighborhoods are hotter than non-redlined neighborhoods in 94 percent of the more than 100 cities studied, with surface temperature differences within the same city topping 12 degrees.
“Case study research of heat islands in individual cities consistently identify resource-limited communities in the hottest zones, but our team wanted to see if there was a consistent pattern at the national scale,” said paper co-author and Science Museum of Virginia Scientist Jeremy Hoffman, Ph.D. “This is the first nation-wide study to explore a relationship between long-run community development—or lack thereof—and susceptibility to climate change.”
Working with Vivek Shandas, Ph.D., professor of urban studies and planning at Portland State University, and Nicholas Pendleton, a student in the Center for Environmental Studies at Virginia Commonwealth University, Hoffman compared the following data sets of 108 urban areas in 29 states:
In the 1930s and 1940s, the Home Owners’ Loan Corporation divided 239 urban areas with a population of more than 40,000 into color blocks. The green, blue, yellow and red outlines ranked neighborhoods on perceived safety for lending and investment, from best to hazardous for lending. For the red-colored, or redlined, areas, the corporation recommended that lenders “refuse to make loans in these areas,” or do so only on a conservative basis.
Areas that were identified as red were referred to as having “undesirable populations” and had a consistent pattern of being lower wealth, lower land value and communities of color and immigrants. Highlighting this with the color-coded maps, and making recommendations on what to do in those areas, deprived entire neighborhoods access to credit. The resulting lack of investment likely set in motion the problems related to social poverty we observe today.
While the federally supported neighborhood ranking practice was banned in 1968, today those formerly redlined communities have fewer trees, less green space and more impervious surfaces (such as asphalt parking lots, roads and brick buildings), factors that contribute to hotter temperatures during heat waves. The research shows this, as redlined neighborhoods across the country are on average about 5 degrees warmer than non-redlined neighborhoods.
Exposure to extreme heat can lead to negative health impacts, such as elevated risks of dehydration; increased cases of heat exhaustion and heatstroke; and may exacerbate other nervous system, respiratory, cardiovascular and diabetes-related conditions. In addition, it can also increase the prevalence of air pollution and smog, threatening complications for people who have respiratory conditions like asthma.
“We are not necessarily saying that the redlining maps created environmental disparity, but we are saying they likely locked it in,” said Hoffman. “The decades-long lack of investment for redlined communities has left these neighborhoods less prepared for, and therefore more heavily impacted by, climate change, specifically extreme heat. Compared to non-redlined communities, the residents in these areas are already experiencing a climate-changed world, just on the other side of town.”
“The patterns of the lowest temperatures in specific neighborhoods of a city do not occur because of circumstance or coincidence,” said Shandas. “They are a result of decades of intentional investment in parks, green spaces, trees, transportation and housing policies that provided ‘cooling services,’ which also coincide with being wealthier and whiter across the country. As climate change brings hotter, more frequent and longer heat waves, the same historically underserved neighborhoods—often where lower-income households and communities of color still live—will face the greatest impact.”
The team views this research as a roadmap for the urban areas included in the study as residents, elected officials, organizations and businesses work together to build resilience to climate change. The data can help communities be more efficient by concentrating limited resources in the areas that need them most and more effective by creating the highest impact.
As part of the paper’s release, the team will be making available an interactive map that allows website visitors to explore the data examined by the researchers. The public can visit the site to see the color-ranked, impervious surface, tree canopy and land surface temperature data overlaid onto a map of all 108 urban areas.
“This is actually a hopeful story,” said Hoffman. “These new data highlight that decisions made 100 years ago still impact us today. That tells me that informed, equitable decisions now could have lasting positive impacts for the next century.”
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