Scientists studied how trees in cities help keep temperatures cooler around the world. They looked at nearly 9,000 large cities to understand how much trees reduce heat.
Trees cool cities in two ways. First, they release water into the air, which cools things down. Second, they create shade that stops pavement and buildings from getting too hot. Right now, trees reduce city temperatures by about half of what they could be without any trees at all.
The research found a big problem. Climate change will make cities much hotter by 2050, warming them by about 1.5 degrees Celsius. However, even if cities plant as many trees as possible, the trees will only cool temperatures by about 0.3 degrees. This means trees alone cannot stop the heat from climate change, even though they do help.
The study also showed that poorer neighborhoods often have fewer trees and are hotter. This makes the heat problem worse for people who already face other challenges.