Heat Islands Offer No Escape From Extreme Weather

Extreme Weather is Intensified on Heat Islands

As Boston gets warmer due to climate change, city officials worry that "heat islands" -- areas with little green space -- will continue to make summers more difficult for the city's low-income and minority neighborhoods. While cities tend to be warmer than suburban areas, city heat doesn't reach the same level in wealthier neighborhoods that have more parks and trees.

As Reverend Mariama White-Hammond, the city's environment chief explained to the Boston Globe, much of the disparity could be attributed to the city's history of racial inequity, in which banks "redlined" certain neighborhoods, making it difficult for people of color to obtain mortgages and leaving those neighborhoods with less green space and other public investments.

Why This Matters

Extreme heat is a growing threat -- over the past 10 days the Pacific Northwest (PNW) experienced a once in a millennium heat dome. Hundreds of people have now died as a result of a heatwave that scorched PNW. In Oregon, 63 people have died in the last seven days, and British Columbia reported 486 deaths between last Friday and Wednesday alone.

  • By the end of the decade, city temperatures could exceed 90 degrees for over 40 days a year -- and by as many as 90 days annually in 2070 -- compared with an average of 11 days in 1990, according to city projections.

Rising heat is a killer: each year 12,000 Americans are killed by heat. One major study hypothesized that heat-related deaths in the coming decades could be more than 50% higher than they were a few decades ago.

These risks are not felt equally -- on average, neighborhoods with a majority of people of color have 33% less tree canopy than white communities. Meanwhile, neighborhoods with 90% or more of their residents living in poverty have 41% less tree canopy than communities with only 10% or less of the population below the poverty line.

NASA: Earth Observatory image of temperature anomalies on June 27th, 2021 compared to 2014-2020 average for the same day during the 2021 western North America heatwave.

WW0: Global Climate Justice - Rt Hon David Lammy MP in Conversation with Catherine Coleman Flowers, April 7, 2021.

Beating The Heat

Boston is currently trying to add green space to its lower-income neighborhoods by planting trees. But the city has to figure out not only how to plant these trees but also keep them alive. Between 2008 and 2017, the city planted 9,809 street trees and removed 5,815 -- a net gain of fewer than 4,000 -- despite pledges by city officials to plant 100,000 trees in that time. It will be particularly difficult to keep these trees hydrated as temperatures continue to rise and the state plunges into drought.

As a response, city officials have piloted a "heat resilience" study and this month begun holding idea sessions in the most affected neighborhoods. The first step involves setting up "cooling zones" at several neighborhood libraries, where they’ll be handing out towels and misters.

Boston isn’t the only city with intense heat islands: a new report by American Forests estimated that more than 500 million trees must be planted and protected in urban areas around the country to reduce heat disparities.