Comprensión auditiva TOEFL

🎧 Transcripción de audio

Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about urban heat islands—cities that are significantly warmer than surrounding rural areas. One major cause is the replacement of natural surfaces with concrete and asphalt, which absorb and retain heat. Another factor is waste heat from vehicles and air conditioning. But there's a lesser-known contributor: the lack of vegetation. Trees and plants cool the air through evapotranspiration, a process where water evaporates from leaves, reducing surrounding temperatures. In many cities, we've removed trees to make way for buildings, making the heat island effect worse. So, what can we do? One solution is green roofs—covering rooftops with soil and plants. Studies show that green roofs can lower rooftop temperatures by up to 30 degrees Celsius during summer. They also absorb rainwater and provide insulation, reducing energy needs. However, installing them costs more than traditional roofs, and not all buildings can support the extra weight. Still, many cities are offering incentives to encourage their adoption. Now, I want you to think about this: if we were to retrofit every suitable building in a city, what overall impact might we expect?