Today in our environmental science lecture, we'll discuss the impact of urban green spaces. A recent study in Melbourne found that adding parks and community gardens can reduce local temperatures by up to 3 degrees Celsius during summer heatwaves. Interestingly, the cooling effect is strongest within 50 meters of the green area, but it diminishes beyond 200 meters. The study also showed that vertical gardens on building walls are less effective than ground-level parks because they provide less shade and water evaporation. However, vertical gardens are valuable in cramped city centers where ground space is scarce. So, while ground-level parks are the priority, we should consider a mix of both designs for maximum benefit.