A study of 108 US cities finds poor neighborhoods can be as much as 12.6 degrees Fahrenheit hotter than richer ones due to lack of trees and green spaces
- A new study looked at ground temperature data for 108 cities across the US
- It compared the average temperature in areas that had a history of redlining
- Redlining was a racist policy used from 1935 to 1986 that labeled areas with high concentrations of black Americans as unsafe for investment or lending
- Areas that had previously redlined were 4.7 degrees Fahrenheit hotter
- Portland, Oregon had the biggest temperature difference with 12.6 degrees
A new study of average temperatures in 108 US cities shows that neighborhoods with a history of redlining are on average 4.7 degrees hotter than other parts of the city.
A joint project from Virginia Commonwealth University and Portland State University, the study combined satellite data showing ground temperatures for different cities along with historic maps that showed which neighborhoods had a history of being redlined.
Formerly redlined neighborhoods were not just consistently hotter, but in some cases the temperature difference reached into the double digits.
A study of ground temperatures in 108 US cities found that neighborhoods that had previously been affected by redlining policies were on average 4.7 degrees Fahrenheit hotter than other areas
Portland, Oregon had the most extreme difference between neighborhoods, with some formerly redlined neighborhoods experiencing temperatures up to 12.6 degrees Fahrenheit hotter than other parts of the city.
Denver and Minneapolis both had major differences as well, ranging between 10 and 12 degrees Fahrenheit, according to a report in Vice.
The practice of redlining dates back to 1935 when the Federal Home Loan Bank Board commissioned ‘residential security maps’ to rank which parts of a city were safe for development projects or home loans.
The safest areas were outlined in green, and the riskiest were outlined in red, which in practice prevented black communities across the country from having access to mortgages and other financial resources to develop their homes and neighborhoods.
The practice was finally banned by the Fair Housing Act in 1986, but decades of underfunding and institutional discrimination have left redlined areas substantially poorer than other parts of their cities.
These areas often lack trees and parks and have more densely packed lots and are covered with blacktop and concrete that reflects heat and significantly raises ground temperatures.
‘Trees leaves will absorb heat and some of the water that’s in the tree itself will be evaporated, creating an increase in relative humidity and potentially cooling that immediately surrounding space,’ Portland State researcher Vivek Shandas told Vice.
‘Whereas other, more dense materials—like asphalt, concrete, cinder block or even brick—will absorb that heat and hold on to it.’
‘Even after the sun goes down, they retain the heat and continue to amplify temperatures locally.’
Portland, Oregon was the city with the biggest temperature differential, with formerly redlined neighborhoods as much as 12.6 degrees Fahrenheit hotter than the rest of the city. Formerly redlined areas of Denver and Minneapolis were also 10 to 12 degrees warmer
Ashton Simpson, a resident of Rosewood, a formerly redlined neighborhood in East Portland, described the challenges of living in the neighborhood.
‘You’ve got heat radiating from the street, heat radiating from the sidewalks, heat radiating from the tops of roofs, heat radiating from the parking lots, heat radiating from cars,’ Simpson told Vice.
‘And if you are ill-prepared and have a heat stroke and you’re a person of color…it’s clear that most of us are not ready for that.’
The team combined satellite temperature images with historic city maps that showed regions that had formerly been redlined to reach their conclusions. Redlining was part of a ranking system implemented in 1935 that identified certain neighborhoods as risky to invest in
In early 2020, Portland changed its building code to mandate that multi-development apartment complexes include at least 15 percent of their area for green space and gardens, but it will likely take years before the positive effects are felt.
In the meantime, Rosewood residents and many others in formerly redlined areas will continue to suffer in the heat.
‘If you’re not going outside and you don’t have air conditioning, you are going to be exposed to temperatures that are much warmer than immediately outside of your home,’ Shandas said.
‘Those communities face some pretty catastrophic outcomes if we have a heatwave come through during this stay-at-home order.’
