Addressing Extreme Heat in Boston: Heat Resilience Study

Written by: Isabella Gambill, Senior Policy Advisor on Climate, Energy, & Resilience




With recent news from the Pacific Northwest showing buckling highways and melting cables during record-breaking heat waves, to Boston’s hottest June ever recorded, extreme heat continues to be an urgent climate threat that claims more lives than any other natural weather event. In addition to heat’s systemic threats of more frequent power failures, tree canopy and green space loss, reduced air and water quality, increased strain on our healthcare systems, and slow or disrupted transportation infrastructure – extreme heat is deadly for our residents, and poses significant risks to our communities’ health and survival. While heat in our changing climate impacts all neighborhoods in Boston, the health risks of extreme heat in our communities are not borne equally across our city.


What scientists refer to as the “urban heat island effect” that causes urban spaces with more concrete, steel, and buildings to be significantly hotter than suburban or rural areas, means that Boston’s neighborhoods with the least amount of green space like Chinatown, Dorchester, East Boston, Mattapan, and Roxbury, are also the hottest and most vulnerable during extreme heat weather events. During heat waves, residents in these urban heat islands can experience temperatures up to 40 degrees Fahrenheit warmer than suburban neighborhoods in Greater Boston1; places like Chinatown struggle to cool down at night due to residual heat kept in pavement and buildings – meaning that there is high risk and little relief for its residents during heat waves.


Although extreme heat has impacts on human health, infrastructure, and economic opportunities that will affect all Bostonians, the heat burden is not felt equitably across our city. Extreme heat is a significant climate justice issue that disproportionately threatens Black, Brown, Indigenous, low-income, and communities of color - the same communities that live in urban heat islands like Chinatown, Dorchester, East Boston, Mattapan, or Roxbury. These 5 urban heat islands in Boston are closely linked with neighborhoods that have a legacy of inequitable neighborhood investment known as redlining.



In 1938, the Division of Research and Statistics designed a grading system for the Home Owners’ Loan Corporation, which rated each Boston neighborhood according to perceived riskiness for mortgage lending and produced a map showing neighborhoods that were anywhere from “best” suited for lending (green) to “hazardous” (red) – a rating system that was highly correlated with the racial makeup of the neighborhood. This rating system and associated map of Boston’s neighborhoods,  referred to as “redlining,” labeled many communities of color as “redlined” communities, or neighborhoods that were deemed too hazardous for lending. It was therefore nearly impossible for people of color to qualify for mortgage loans, which reduced stability in neighborhoods of color and prevented their residents from wealth-building associated with homeownership. Many public and private investments throughout Boston’s neighborhoods were patterned based on these redlining maps, with profound impacts on certain neighborhoods’ urban tree cover and green spaces, resulting in  today’s urban heat islands in Boston. If you overlay historic, racist redlining maps with current heat island maps in the City of Boston, it becomes clear that extreme heat cannot be separated from climate and racial justice work.


The effects of redlining and legacies of inequitable investment across Boston’s neighborhoods are still profound today. The same communities that were redlined on racial grounds have seen repeated disinvestment in parks, open spaces, and urban tree cover, thereby creating more concrete, steel, and building-heavy neighborhoods that are more susceptible to the negative impacts of extreme heat. As you can see from the figure below, areas that were redlined and denied mortgage lending and other investments in the past are hotter today.


Source: City of Boston Extreme Heat Open House



In order to address the climate and equity issues surrounding extreme heat in Boston, the City has launched a Heat Resilience Study to investigate heat reduction strategies in five of Boston’s urban heat islands: Chinatown, Dorchester, East Boston, Mattapan, and Roxbury. The Study focuses on areas where heat islands overlap with historically underserved communities in Boston, and it seeks to identify strategies that will: strengthen policies and programs needed to reduce urban heat and heat risk; address current and future impacts of extreme urban heat; integrate existing preparedness, public health, and racial equity initiatives; and inform citywide solutions for heat resilience. Over the past several months, the City has been hosting Heat Resilience Study open houses, heat resilience idea sessions with local communities, and has formed both a Community Advisory Board and Steering Committee to oversee the Heat Resilience Study. A Better City has participated in several Heat Resilience Study open houses and idea sessions.


Although the Heat Resilience Study is still underway, community idea sessions and open houses led by the City of Boston have already been extremely informative. Suggestions have included identifying and expanding priority shading areas, enhancing and adding public cooling centers, developing heat escape vouchers, and creating a Community Cooling Network that can engage non-profits, religious institutions, and businesses to respond to extreme heat events. The City also seeks to find solutions for cooler homes and neighborhoods through programs for owners and renters, cool roof initiatives, designating Neighborhood Climate Captains and participatory budgeting, and by expanding energy assistance and utility policies. Finally, the City is also exploring opportunities for creative uses of the public realm, in which cool pavement, pocket or pop up “micro parks”, added street trees, creative awnings and shade devices for businesses, and shaded bus stops could help to provide cooler main streets and climate-ready small businesses. Across all heat resilience solutions, it will be important for the City, for residents, and for small businesses to consider trade-offs and synergies with climate resilience solutions (ex. the trade-off of cool pavement vs. more permeable options for flood mitigation).


Alongside the Heat Resilience Study, the City is also pursuing a 20-year Urban Forest Plan and an Open Space and Recreation Plan, which will help to address extreme heat and improve and expand green space access across Boston’s neighborhoods. A Better City sits on the newly established Urban Forest Plan’s Community Advisory Board (CAB) as a Community Partner, and continues to engage in the Heat Resilience Study Open Houses and Idea Sessions. More information on the Urban Forest Plan and associated CAB will be provided in a separate blogpost in the coming weeks.


Boston’s Heat Resilience Study is anticipated to be finalized in late Summer 2021, and A Better City intends to host a joint event with the Green Ribbon Commission on what role(s) the private sector can play in helping to combat extreme heat in our communities once the findings of the Study become available. For more information on the City of Boston’s Heat Resilience Study, heat mapping in Boston, and for materials from recent open houses on extreme heat, please visit the City of Boston’s Preparing for Heat landing page.


The Energy and Environment Unit at ABC recently committed to extreme heat as a key policy priority in our updated 2021-2022 E+E Policy Agenda and look forward to engaging in further initiatives that address extreme heat threats in our city. In both our E+E policy work and in our Equity in the Built Environment Work Plan, we continue to address extreme heat as both a climate and racial justice issue.


For more information on A Better City’s work on extreme heat and the Urban Forest Plan, please contact Isabella Gambill.




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