Heat Islands: Low-Income, Minority Neighborhoods Have Fewer Trees

The result? Low-income and minority communities across the U.S. feel the effects of climate change more acutely than white, wealthy neighborhoods.

(Courthouse News photo / William Dotinga)

(CN) — Years of research has provided overwhelming evidence that low-income neighborhoods in America are hotter than wealthier areas largely due to a lack of trees.

A study published Wednesday in the journal PLOS One further revealed 92% of urban communities reinforce this trend providing an average of 30% less tree coverage to poorer areas.

Trees provide more benefits than just creating oxygen — they also help to lower temperatures by way of evaporation of water on their leaves. They provide shade, improve air quality, and are vitally important for highly populated cities. Consequently, a lack of tree coverage in urban areas can put people at risk in the summer and during heat waves, a trend seen predominantly in low-income and minority communities. 

Cities are often hotter than suburban or rural areas due to a phenomenon known as urban heat islands. When pavement is laid and vegetation is scarce, temperatures naturally rise, an effect made worse by heat-retaining asphalt and tall buildings that block wind. This becomes an especially critical factor considering that not only do low-income neighborhoods lack significant tree coverage, but they are often near industrial areas or highways, due to unethical policies like redlining.

Tree cover for United States large urbanized areas. a.) Population-weighted median tree cover. b.) The absolute difference between low-income blocks (lowest quartile of income) and high-income blocks (highest quartile of income) in tree cover. (Image courtesy McDonald et al, 2021, PLOS ONE [CC-BY 4.0, https://creativecommons.org/licenses/by/4.0/])

Lead author Robert McDonald of The Nature Conservancy in Arlington, Virginia, and a team of researchers wanted to put a number to the inequality and find out just how much a lack of tree coverage affects temperature in low-income and minority communities. They analyzed this trend block by block using images from the National Agriculture Imagery Program and data from NASA’s Landsat satellite, looking at the tree coverage across 5,723 cities, towns, and other habitations that in all are home to about 167 million people.

The results found that 92% of the communities studied showed an unequal distribution of urban tree coverage among low-income neighborhoods. These blocks had 15.2% fewer trees than high-income areas, which subsequently resulted in these blocks being an average of 2.7 degrees hotter. The trend is most acute in the Northeast U.S., with the most significant disparities showing 30% less tree coverage in low-income blocks and temperatures that run 7.2 degrees hotter.

McDonald and his team also confirmed what we already know — that most of the people affected are people of color. Even after factoring in population density and income, the authors found a clear pattern between communities of color and overheated blocks. 

“We had expected low-income and minority neighborhoods to have less tree cover and so be more at risk during summer heat waves, but we were still surprised and troubled at how widespread this tree inequality was, with 92% of communities having lower tree cover in low-income than in high-income areas,” the authors said in a statement accompanying the study.

The trend is not isolated, and as the effects of climate change continue to present themselves it becomes even more evident that the wealthy will have more resources and protection. Those with access to air conditioning or homes in cooler areas are less likely to feel the effects of a city-wide heat wave than those in poverty-stricken areas.

Policies like the Green New Deal offer solutions, including heat-resistant roofs and an investment in increased tree coverage, but for now neighborhoods continue to feel the inequality. As of 2019 some of the biggest offenders of this unequal distribution of trees in urban blocks included Oakland, Las Vegas and Baltimore. 

“Low-income communities have for too long borne the brunt of the climate crisis,” Los Angeles Mayor Eric Garcetti said in 2019. “Our Green New Deal confronts that history of environmental injustice in practical ways — like bringing cool roofs, cool pavements, expanded tree canopy and other remedies to our hottest areas — that can make a real and direct impact in people’s lives as well as contribute to the long term change needed to safeguard our future.”

The study authors estimate there are a staggering 62 million fewer trees in low-income blocks than in wealthy areas, a problem that requires swift correction as summers become hotter and longer. In fact, hospitals in these low-income blocks often experience a surge in people experiencing respiratory distress, cardiac arrest, high blood pressure, dehydration and more during intense heat.

A significant investment of $17.6 billion dollars is needed to plant more trees and vegetation in urban neighborhoods, the study authors say, which could improve the quality of life for millions of people and help the U.S. move a step closer to achieving equality.

%d bloggers like this: