Nghe TOEFL

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Listen to part of a lecture in an environmental science class. Professor: Today we're discussing the concept of 'green roofs'—rooftops covered with vegetation. Now, green roofs aren't just about aesthetics. They offer significant environmental benefits, particularly in urban areas. One key advantage is stormwater management. In cities, heavy rain often overwhelms sewer systems, causing flooding. Vegetation and soil on a green roof absorb rainwater, slowing down its release into the drainage system. This reduces the risk of overflow. Another benefit is the urban heat island effect. Dark rooftops absorb heat, raising city temperatures. Green roofs, however, reflect sunlight and cool the air through evapotranspiration, helping to lower ambient temperatures. Additionally, green roofs provide insulation, reducing heating and cooling costs for buildings. Some critics point out the high installation cost, but proponents argue that long-term energy savings and extended roof lifespan offset this initial expense. Overall, while green roofs require investment, their ecological and economic advantages make them a viable solution for sustainable urban development. Now, let's consider a practical example...