Today in our environmental science lecture, we're discussing urban green spaces. A recent study in Melbourne found that parks can reduce local temperatures by up to 4 degrees Celsius during heatwaves. Interestingly, the cooling effect is strongest within 50 meters of the park's edge, but it diminishes rapidly beyond that. The study also noted that trees with large canopies are more effective than grass areas alone, because they provide shade and release moisture through transpiration. However, the researchers emphasized that regular maintenance, such as watering during dry periods, is crucial for these benefits to persist.