Today in our environmental science lecture, we'll discuss urban heat islands. As cities grow, concrete and asphalt absorb sunlight and re-radiate heat, making urban areas warmer than surrounding rural regions. This effect is intensified by lack of vegetation and waste heat from buildings and vehicles. One solution is green roofs, which can reduce rooftop temperatures by up to 30 degrees Celsius. However, their effectiveness depends on climate and building structure. For instance, in dry regions, irrigation needs may offset benefits. Therefore, planners should consider local weather patterns before implementing such measures.
❓ According to the lecture, what is a key limitation of green roofs?
A. They are too expensive to install in most cities.
B. Their effectiveness varies with local climate conditions.
C. They increase indoor temperatures in summer.
D. They require constant replacement of soil layers.
✅ 正确答案
Their effectiveness varies with local climate conditions.