temperatures are rising in boston, and redlined areas face the greatest impact, data shows

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Katie Delaney

Dec. 10, 2022

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            Areas that were redlined in Boston are 7.5 degrees hotter in the day than areas that were labeled as “best,” according to Boston’s Heat Resilience Plan.

            The Heat Plan analyzes extreme temperatures across Boston to show where the greatest impacts are and how different communities, particularly redlined ones, are impacted.

            Redlining began in the 1930s, when the U.S. government created maps of cities and used a grading system to rank neighborhoods, rating the riskiness of providing loans for mortgages. The grades were “best,” “still desirable,” “declining,” and “hazardous.” The ranking system was largely based on racial demographics, with communities of color, immigrant communities, and lower-income areas typically given low grades.

            For decades, people in redlined, or “hazardous” areas were denied access to mortgages and other credit, creating a cycle of disinvestment. Redlining was outlawed in 1968 with the Fair Housing Act, but the impacts of redlining have continued for decades.

            Zoe Davis, the Climate Resilience Project Manager for the Heat Plan said in an interview, “and that is due in part to where private investment, which was then followed by public investment, was directed.” She said that through their analysis in the Heat Plan, they found that “the areas that were redlined, typically have less green space and more impervious dark hardscape,” due to a lack of funding.

            Boston is an urban heat island, meaning that it is significantly warmer than its surrounding suburban areas due to the low number of trees and vegetation and the high amount of dark, paved and impervious surfaces like asphalt roads. Those surfaces absorb more heat than light colored surfaces, leading to extreme heat, particularly in redlined areas. Redlined neighborhoods in Boston have 20% less parkland and 40% less tree canopy than areas designated as “best,” according to the Heat Plan.

            David Meshoulam, the executive director of Speak for the Trees Boston said in an interview, “what you see from that is higher summer temperatures, increased air pollution, more flooding in basements, and higher levels of stress.”

            Extreme heat that is exacerbated by a lack of greenery is a public health issue. According to the Heat Plan, “extreme heat can cause negative health impacts, including direct loss of life, increases in respiratory and cardiovascular diseases, and challenges to mental health.”

            Temperatures in Boston are also on the rise due to carbon emissions, which is especially a problem for communities that are already so vulnerable to extreme heat.

            According to the Heat Plan, in Massachusetts, temperatures have increased by 3.5 degrees since the beginning of the 20th century. And the number of hot days in Boston continues to rise. In the last decade, Boston experienced more hot (over 90 degree) days than any decade in the previous 50 years.

            Some of the hottest neighborhoods in Boston are Roxbury, Dorchester, East Boston, and Chinatown, which were all redlined, and Mattapan, which was given a grade of “declining.” The Heat Plan focuses on strategies to reduce the risk of extreme heat in these areas. Davis said the Plan focuses on these communities to “have some criterion to focus where investment should be…because that is historically where investments have not been in the past.”

            The Heat Plan outlines the City of Boston’s strategies to mitigate extreme heat, particularly in these communities. They have three main goals: to reduce heat exposure, adapt to heat, and reduce sensitivity and foster healthy, connected communities. Some of the strategies include expanding access to cooling centers, making information on how to stay cool more accessible, reducing dark surfaces and pavement, and increasing trees and shade.

            Speak for the Trees is an organization that is also trying to do just that. Their mission is to bring tree equity to Boston, to increase the greenery in the communities that need it most, preserving and planting trees around the city.

            “We do a lot of work around planting and caring for trees, about educating people about trees and how to care for them and why they're important, but also in developing community partnerships” Meshoulam said.

            They’re working to cool down these communities and want to ensure that people understand how much of an impact trees can make.

            “We really want to make sure at its core that everyone in Boston understands and appreciates the importance of trees…and that we all work together: residents, institutions, private institutions, public institutions, and the government and municipality to ensure that our tree canopy not only survives, but thrives,” Meshoulam said.

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