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 a green space reported better mental health. But researchers warned that simply adding grass without trees does little to combat urban heat, and recommended prioritizing tree planting in disadvantaged neighborhoods.
❓ According to the lecture, what condition is necessary for urban parks to significantly reduce local temperatures?
A. A. The park must be larger than 500 meters in diameter
B. B. The park should have at least 30% tree canopy coverage
C. C. The park must be located in a disadvantaged neighborhood
D. D. The park should have open lawns rather than dense trees
✅ 正确答案
B. The park should have at least 30% tree canopy coverage