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 cooling effect depends on tree canopy coverage. Areas with less than 30% canopy showed minimal temperature differences. Interestingly, the study also noted that residents living within 500 meters of a large park reported better mental health, but only if the park had maintained walking paths. Without these paths, usage dropped significantly, especially among elderly people.
❓ According to the lecture, what condition is necessary for a park to have a significant cooling effect?
A. A. The park must be larger than 500 meters in diameter.
B. B. The park must have at least 30% tree canopy coverage.
C. C. The park must include maintained walking paths.
D. D. The park must be located in a residential area.
✅ 正确答案
B. The park must have at least 30% tree canopy coverage.