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Study shows Boston has the sixth-highest heat intensity across the country, tied with Miami and Chicago
“Boston is one of the very few cities in the US, where there are a lot of irregular streets.”
Boston was ranked the sixth highest heat intense city in the United States, tied with Miami and Chicago, according to a recent climate study.
Climate Central, an independent organization that researches climate change, released a report on July 14 that ranks 159 US cities by their urban heat intensity index. The study refers to these cities as “urban heat islands.”
Each city was given an index score which represents the average temperature difference between the city and what the heat may have been in that location if not an urban area.
This score was primarily based on – in order of consideration – albedo (the reflectivity of the surfaces in the city, such as rooftops and roads), percentage of greenery, population density, building height, and average street width and city irregularities.
Boston’s index was 7.24 degrees Fahrenheit and Climate Central said the biggest factors were building height and population density. The city recently reported one of its hottest summers on record.
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“Population density was key [in Boston]…because people create heat by running appliances – things like air conditioning,” said Peter Girard, director of communications at Climate Central. “The more people you have in a small place, the more heat it contributes, and the more it becomes a factor in this study.”
Ranked above Boston was New Orleans, Louisiana – in first place with an 8.94 index – followed by Newark, New Jersey, New York City, New York, Houston, Texas, and then San Francisco, California. Chicago, Illinois, and Miami, Florida also shared Boston’s 7.24 Fahrenheit index.
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“Cities in the Midwest and Northeast, such as New York, Newark, Boston, Chicago, Providence, Detroit and Cleveland have more compact, historically built-out environments, with taller buildings,” the report said. “These factors add to the intensity of their urban heat island footprint.”
Girard added Boston stood out particularly to researchers because of its irregular map, unlike the majority of US cities. Girard said this factor was not calculated in this study – because Boston was the only US city that had this factor – but it could impact the actual heat intensity.
“Boston is one of the very few cities in the US, where there are a lot of irregular streets. In general, in cities that are laid out in grids or have particularly wide streets, air flow is increased,” Girard said. “Because of that, the tendencies or the temperatures they accumulate can dissipate as the wind moves through them.”
Girard said unlike cities like New York City, building height barely impacted Boston’s score, since the city’s tall buildings are only downtown.
Other New England cities made the top twenty list, such as Burlington Vermont in 13th place with a 7.05 heat index and Providence in 10th place with a 7.08 heat index. Providence was tied with Baltimore, Maryland, Sacramento, California, and Salinas, California.
Girard said one way Boston can tackle the high heat intensity is through lowering the city’s albedo: many rooftops in Boston could be turned into green roofs and lighter reflective roofs, called “cool roofs.”
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Girard added that increasing green space – even as small as adding plants on medians – can have a dramatic effect. Washington DC’s heat index score was relatively low – despite many people’s initial expectations – largely due to their large percentage of green space, Girard said.
“In the world of climate analysis, there’s so much bad news, and some of it can be really grim,” Girard said. “And the idea that this one you’ve got some solutions that are accessible and don’t require billions of dollars, or generational projects is really encouraging.”
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