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Trees Counter Half of Urban Heat in Cities, But Inequities Persist
Trees are providing significant relief from urban heat in cities worldwide, according to a new study published in Nature Communications. Researchers found that urban trees counteract nearly half of the warming caused by the urban heat island effect, cooling cities by an average of 0.27 degrees Fahrenheit (0.15 degrees Celsius).
Without tree cover, the study determined that buildings and pavement would increase urban temperatures by an average of 0.56 degrees Fahrenheit (0.31 degrees Celsius). This urban heat island effect occurs when dark surfaces absorb and retain heat, creating localized warming separate from climate change caused by fossil fuels.
“When you look at cities globally, there are many, many cities, especially in developing countries, that have very low tree cover,” said Rob McDonald, lead author and scientist at the Nature Conservancy. The research analyzed temperatures across nearly 9,000 large cities by measuring discrete segments of approximately 150 city blocks, allowing researchers to capture neighborhood-specific cooling effects.
The study revealed stark inequalities in tree coverage and cooling benefits. While about 185 million people living in 31 major cities experience at least a half-degree Fahrenheit cooling from trees, residents in poorer and hotter urban centers receive far less relief where it’s most critically needed.
Twenty large cities with populations over 3 million experience minimal cooling—less than a tenth of a degree Fahrenheit—from urban trees. In four cities—Dakar, Senegal; Jeddah, Saudi Arabia; Kuwait City and Amman, Jordan—tree cover is so sparse that more than 15 million residents receive virtually no cooling benefits.
The disparity between wealthy and developing nations is particularly striking. Nearly 40% of cities in affluent countries receive substantial cooling of at least 0.45 degrees Fahrenheit (0.25 degrees Celsius) from trees, while less than 9% of cities in the poorest countries achieve similar benefits.
Cities with the most effective tree-cooling include Berlin, Atlanta, Moscow, Washington, Seattle and Sydney. Atlanta stands out with 64% of its land area under tree canopy. Chris Greene of Canada’s University of Dalhousie, who wasn’t part of the study, noted that wealthy areas in North America benefit from larger lot sizes, individual property ownership, and residents with more political influence—all factors contributing to greater tree cover.
Thomas Crowther, an ecologist at the King Abdullah University of Science and Technology in Saudi Arabia, emphasized the importance of addressing these disparities. “As up to 75% of the human population shifts towards living in urban environments, these buffering effects of urban vegetation are going to be vital,” said Crowther, who wasn’t involved in the research. “But we have to overturn the devastating inequities in the distribution of urban trees, so that their benefits can be experienced by the low- and middle-income communities that are often most vulnerable to the effects of extreme temperatures.”
The researchers emphasized that while cities should increase tree coverage—particularly in poorer and hotter regions—there are limitations due to water availability, suitable land, appropriate species, and worsening climate change. At best, increased urban tree cover might reduce future urban heating by about 20%, according to McDonald.
“Trees won’t save us from climate change,” McDonald cautioned. “The climate scenarios are showing a much warmer world and there’s only so much of that that tree cover can help with.”
In 2019, Crowther and colleague Jean-Francois Bastin suggested in Science magazine that planting a trillion new trees globally could help absorb carbon dioxide. However, University of Michigan environment dean Jonathan Overpeck, not involved in the current study, emphasized that while trees help fight climate change in multiple ways, “this strategy is not nearly enough to slow climate change to a significant degree.”
“Only by transitioning away from fossil fuels in favor of renewable energy and battery storage can we hope to halt the climate change that is wreaking havoc around the planet,” Overpeck stated.
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12 Comments
The cooling power of urban trees is remarkable. This research underscores the critical role that green infrastructure plays in moderating city temperatures. The inequities in tree coverage are concerning and should spur efforts to ensure more equitable distribution of this valuable natural resource.
I agree, the inequities in urban tree canopy coverage need to be a priority for city planners and policymakers. Addressing this issue could yield significant climate and quality-of-life benefits for underserved communities.
The findings on the significant cooling impact of urban trees are quite impressive. This underscores the immense value of protecting and expanding urban forests as a climate change mitigation strategy. At the same time, the persistent inequities in tree coverage are concerning and deserve further attention.
This is a fascinating and important study. The ability of urban trees to offset half of the heat island effect is really remarkable. However, the unequal distribution of this cooling resource is quite troubling and needs to be addressed.
This study highlights the immense value of urban trees in combating the heat island effect. The finding that they can offset half of the warming is really impressive. However, the persistence of inequities in tree coverage is troubling and needs to be addressed through comprehensive urban greening strategies.
Fascinating study on the urban heat island effect and the cooling power of trees. It’s great to see quantifiable evidence of the significant climate benefits that urban forests can provide. However, the inequities in tree coverage are concerning and need to be addressed.
The study’s findings on the significant cooling effect of urban trees are compelling. It’s clear that investing in urban forestry should be a key climate adaptation strategy for cities. However, the persistent inequities in tree coverage are concerning and deserve more attention.
Absolutely. Ensuring equitable access to the climate benefits of urban trees should be a critical consideration in urban greening initiatives. This is an important equity and environmental justice issue that warrants further research and policy action.
This is an important reminder of the crucial role trees play in moderating urban temperatures. The findings highlight the need for more equitable tree planting and urban greening initiatives, especially in underserved communities. Investing in urban forests can yield significant climate and quality-of-life benefits.
Wow, the temperature reductions enabled by urban trees are substantial. This is a powerful argument for prioritizing tree planting and urban forestry initiatives. The uneven distribution of this natural cooling resource is concerning and deserves attention from policymakers and urban planners.
I agree, the inequitable distribution of urban trees is an important issue that needs to be tackled. Everyone deserves access to the climate benefits provided by a healthy urban forest.
The study’s finding that trees can offset nearly half of urban heat island effects is quite impressive. It underscores the value of preserving and expanding urban tree canopies. However, the persistent inequities in tree coverage are troubling and need to be addressed through targeted policies and programs.