"The urban heat island effect is a phenomenon whereby cities experience higher air temperatures than the surrounding countryside. This effect can be quite noticeable. On average, cities tend to be 1-7°F warmer during the daytime. This difference continues well into the night, during which cities can still be as much as 5°F warmer than the areas around them. Scientists refer to areas afflicted by these higher temperatures as urban heat islands.

"People living in urban heat islands are especially vulnerable to the effects of climate change. As the planet warms, urban heat islands will only intensify those higher temperatures. And since nearly 70% of humanity will live in cities by 2050, finding ways to alleviate urban heat islands has become even more pressing.

"The most obvious way to fight the urban heat island effect is to reintroduce vegetation. Cities can expand parkland, plant street trees, and install 'green roofs' designed to harbor plant life. One study found that the presence of vegetation can lower nearby air temperatures by as much as around 4 °F."

Source: MIT Climate Portal