Today in our environmental science lecture, we'll discuss urban green spaces. A recent study in Melbourne found that parks can reduce local temperatures by up to 4 degrees Celsius during heatwaves. However, the effect depends on tree canopy coverage. Areas with less than 30% canopy showed minimal cooling. Interestingly, small pocket parks with dense trees were more effective than larger open lawns. The study also noted that residents living within 500 meters of such green spaces reported better sleep quality during hot nights. So, when designing sustainable cities, planners should prioritize tree density over sheer park size.