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 cooling effect depends on the park's size and tree coverage. Small gardens with scattered trees only lower temperatures by 1 to 2 degrees, while large parks with dense canopy can create a noticeable 'cool island'. Interestingly, the study also showed that adding water features, like ponds, enhances cooling by an extra 0.5 degrees, but only if the park is larger than 2 hectares. So, for city planners, the key is to prioritize bigger green areas over many small ones.
❓ According to the lecture, what is the most important factor for maximizing the cooling effect of urban parks?