Today in our environmental science lecture, we'll discuss urban green spaces. Researchers have found that parks and community gardens can significantly reduce the urban heat island effect. For example, a study in Melbourne showed that increasing tree canopy by 20% could lower daytime temperatures by up to 2.5 degrees Celsius. However, the key factor is not just the number of trees, but their placement. Trees planted along streets and around buildings provide more cooling than those clustered in a single large park. Additionally, green roofs and vertical gardens on high-rise buildings are becoming increasingly popular, though they require more maintenance and are more expensive to install.