Today in our environmental science lecture, we're discussing urban green spaces. A recent study in Melbourne found that parks with native trees reduce local temperatures by up to 4 degrees Celsius during heatwaves. Interestingly, the cooling effect was strongest within 50 meters of the trees, but it diminished rapidly beyond 100 meters. The researchers also noted that grass areas without shade provided negligible cooling. So, while planting more trees is beneficial, their placement is crucial for maximum impact on city microclimates.