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. However, the effect depends on the size and tree coverage of the park. Small gardens with scattered trees only lower temperatures by 1 degree, while large, densely wooded areas have the most significant cooling impact. Interestingly, the study also showed that adding water features, like ponds, can extend the cooling effect to nearby streets, but only if the park is at least 2 hectares in size. So, city planners should prioritize larger, tree-rich parks over many small ones.