托福听力

🎧 听力原文

Listen to part of a lecture in an environmental science class. Today we're going to talk about urban heat islands, which are areas in cities that are significantly warmer than surrounding rural areas. This happens because concrete, asphalt, and buildings absorb and re-emit heat from the sun more than natural landscapes do. Also, cities have less vegetation, which normally provides shade and cools the air through evapotranspiration. But there are strategies to reduce this effect. One is to increase the number of green roofs—roofs covered with plants. These can lower rooftop temperatures by up to 40 degrees Celsius, and they also improve insulation, reducing energy costs. Another strategy is to use cool pavements that reflect more sunlight. However, these have a limitation: they might not be as effective in narrow streets where buildings block sunlight. A third approach is planting more trees along streets and in parks, which not only provides shade but also captures carbon dioxide. So, while no single solution works everywhere, combining these methods can significantly lower city temperatures.