Today in our environmental science lecture, we're discussing urban green spaces. A recent study in Melbourne found that parks reduce local temperatures by up to 4 degrees Celsius during heatwaves. Interestingly, the cooling effect is strongest within 50 meters of the park boundary, and it diminishes as distance increases. 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, researchers warned that small pocket parks, less than half a hectare, have a negligible impact on surrounding neighborhoods. So, for future city planning, larger interconnected green corridors are recommended over isolated small gardens.