WASHINGTON (AP) — Trees prevent nearly half of the heating caused by pavements and buildings in the world’s cities, but they don’t provide enough cooling in hot, poor cities that are needed most as the world warms, a new study finds.
Across cities around the world, trees can reduce temperatures by an average of 0.27 degrees Fahrenheit (0.15 degrees Celsius) by providing shade and releasing water vapor, according to a study published Wednesday in the journal Nature. nature communications.
Without these trees, the world’s cities would be an average of 0.56 degrees Fahrenheit (0.31 degrees Celsius) warmer. Urban heat island phenomenondark roofs and sidewalks absorb heat. The mechanism of human-induced warming is different from climate change caused by the burning of fossil fuels.
The researchers built an analysis of about 9,000 large cities around the world by measuring temperatures in each of about 150 city blocks. This allows us to capture the cooling effects of cities and neighborhoods, making it no longer possible, for example, for the trees in New York’s Central Park to be responsible for cooling the downtown area of the Bronx several miles away.
Approximately 185 million people living in 31 large cities already feel an average of at least 0.3 degrees Fahrenheit (0.3 degrees Celsius) cooler under tree cover. But the study’s lead author, Nature Conservancy scientist Rob McDonald, said poorer, hotter metropolitan centers that need it most aren’t getting as much relief from high temperatures. You can kill people by confusing their brainswhich shuts down the organs and overworks the heart.
Meteorologists measure the temperature difference between urban centers and nearby rural areas to detect urban heat island effects. Scientists in the study used a combination of weather station measurements, satellite data, and computer models to confirm the cooling tree they provide.
Small tree relief in hot, dry and poor locations
In 20 cities with populations of 3 million or more, residents experience less than a tenth of a degree Fahrenheit (0.05 degree Celsius) of air temperature from the coolness of trees. Four cities – Dakar, Senegal. Jeddah, Saudi Arabia. Kuwait City and Amman, Jordan – With minimal tree cover, the more than 15 million people living there have essentially no cooling from trees.
At the other end of the spectrum, MacDonald focused on cities that are covered by trees and are at least 0.45 degrees Fahrenheit (0.25 degrees Celsius) cooler. Nearly 40% of cities in rich countries have this level of air conditioning, while just under 9% of cities in the poorest countries have such level of tree rescue, the study said.
Mobile home park visible, April 22, 2026, in Newport, Rhode Island (AP Photo/Joshua A. Bickel, File)
Mobile home park visible, April 22, 2026, in Newport, Rhode Island (AP Photo/Joshua A. Bickel, File)
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Topping the list of coolest places is Berlin, which also includes tree-rich Atlanta, Moscow, Washington, Seattle, and Sydney. For example, Atlanta has 64% of its land area under tree canopy, McDonald said. Chris Green of Canada’s Dalhousie University, who was not involved in the study, said wealthier regions in North America have larger land areas, more private owners, and more politically influential residents, all of which contribute to growing more trees and providing more cover.
“There are inequalities,” McDonald said. “If you look at cities around the world, there are so many cities, especially in developing countries, that have very few trees. So I think the temperature cooling numbers were a little lower than expected.”
Thomas Crowther, an ecologist at Saudi Arabia’s King Abdullah University of Science and Technology, said every little thing helps. Where he lives, water is at a premium, so the city is rarely covered in trees to keep it cool.
“As up to 75% of the human population transitions to living in urban environments, this buffering effect of urban vegetation will be critical,” said Krauser, who was not involved in the study. “But we must reverse catastrophic inequalities in the distribution of urban trees so that low- and moderate-income communities most vulnerable to the effects of extreme temperatures can reap the benefits.”
Planting trees won’t save us from climate change
Allie Bujakoski collects native tree seedlings as part of a collection effort in Newport, Rhode Island, April 22, 2026. (AP Photo/Joshua A. Bickel, File)
Allie Bujakoski collects native tree seedlings as part of a collection effort in Newport, Rhode Island, April 22, 2026. (AP Photo/Joshua A. Bickel, File)
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The study authors said cities, especially poor and hot cities, can and should do more to increase tree cover. However, due to limited availability of water, land and suitable species, coupled with worsening climate change, future urban heating will be reduced by at most 20%, McDonald said.
“Trees won’t save us” climate change“Climate scenarios point to a warmer world, and trees can only do so much to help with that,” McDonald said.
Still, planting trees has benefits beyond reducing heat. Krauser and Jean-François Bastin in a study published in Science in 2019 proposed planting 1 trillion new trees — on top of the 3 trillion trees already growing on Earth — not for cooling, but to absorb carbon dioxide.
“While tree planting certainly helps combat climate change in a variety of ways, this strategy is not enough to significantly slow climate change,” said Jonathan Overpeck, dean of the University of Michigan’s School of Environmental Studies, who was not involved in the study. “Only by moving away from fossil fuels and toward renewable energy and battery storage can we hope to halt the climate change that is wreaking havoc on our planet.”
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