In many parts of the world, heatwaves are more and more common, and they affect millions of people.
Cities are becoming too hot, and experts are thinking of methods to cool them. One possibility is to let fresh air move between buildings. Architects design buildings in special ways to help the wind move and lower the temperature. Also, they build structures to provide shade, and they cool people and streets.
Another possibility is to place more plants and trees in streets and on the roofs of buildings. Over fifty years ago, Singapore started to plant trees and make more parks, and now it is one of the greenest cities in the world.
Now, this idea is spreading to other cities. People paint roofs and roads lighter colors because they hold less heat from the sun.