TOEFLリスニング

🎧 リスニング原文

Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about urban heat islands. As you know, cities tend to be warmer than surrounding rural areas. This is because concrete and asphalt absorb and re-radiate heat, while vegetation, which cools through evapotranspiration, is scarce. But there's an interesting solution that's gaining traction: green roofs. A green roof is a rooftop covered with plants and a growing medium, layered over a waterproof membrane. These roofs can reduce surface temperatures by up to 40 degrees Celsius compared to conventional roofs. They also provide insulation, cutting energy costs for heating in winter and cooling in summer. Additionally, they manage stormwater runoff, absorbing rainfall and reducing the burden on sewage systems. One challenge, however, is the initial cost, which is higher than traditional roofing. But over time, the energy savings and extended roof lifespan often offset this. Moreover, green roofs create habitats for birds and insects in urban areas. So, while they're not a panacea, they offer multiple benefits that address both environmental and economic concerns.