托福听力

🎧 听力原文

Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about urban heat islands—that's when cities are significantly warmer than surrounding rural areas. This happens because concrete and asphalt absorb and retain heat, while vegetation, which provides shade and releases moisture, is scarce. One major consequence is increased energy demand for air conditioning, which in turn raises greenhouse gas emissions. But there are solutions. Green roofs, for example, are covered with plants and soil. They not only insulate buildings, reducing heating and cooling needs, but they also absorb rainwater, reducing runoff. Another option is increasing tree canopy in streets and parks. Trees cool the air through evapotranspiration, and they also lower surface temperatures by blocking sunlight. However, implementing these strategies requires careful urban planning and investment. Cities like Chicago and Toronto have already adopted policies to encourage green roofs, and studies show that a city-wide tree planting initiative could reduce peak summer temperatures by up to 2 degrees Celsius. So, while the problem is serious, we have effective tools to combat it.