Today in our environmental science lecture, we'll discuss urban heat islands. Cities tend to be warmer than surrounding rural areas because concrete and asphalt absorb and re-radiate heat. One effective mitigation strategy is increasing green spaces, such as parks and green roofs. However, a recent study in Melbourne found that planting trees along streets can reduce local temperatures by up to 2 degrees Celsius during summer afternoons, but only if the trees are mature and have a wide canopy. Younger trees have less impact. Additionally, the study noted that light-colored pavements reflect more sunlight, but they don't cool the air as much as trees do.