Today in our environmental science lecture, we'll discuss urban green spaces. Recent studies show that parks in cities can reduce the heat island effect by up to 3 degrees Celsius. However, the key factor isn't just the size of the park, but the density of trees. For example, a small park with many mature trees can be more effective than a large open lawn. Additionally, green roofs on buildings contribute to cooling, but they are less effective for ground-level pedestrians. So, when planning new developments, city planners should prioritize tree canopy cover over simply allocating large areas of grass.