Today in our environmental science lecture, we'll discuss urban heat islands. Cities tend to be warmer than surrounding rural areas because concrete and asphalt absorb and re-emit heat. However, a recent study in Melbourne found that increasing tree canopy by just 20% could reduce surface temperatures by up to 4 degrees Celsius. The researchers also noted that green roofs, while helpful for insulation, had a smaller impact on street-level cooling. Interestingly, the study emphasized that the placement of trees is more critical than the total number, as shade on western-facing walls proved most effective during afternoon heat peaks.
❓ 根据讲座内容，墨尔本的研究对于降低城市热岛效应有何发现？
A. 绿色屋顶是街道层面降温最有效的方法。
B. 将树木覆盖率提高20%，可使地表温度降低多达4度。
C. 树木的数量比它们的位置更重要。
D. 朝西的墙壁在下午受到的遮荫较少。
✅ 正确答案
Increasing tree cover by 20% can lower surface temperatures by as much as 4 degrees.