托福听力

🎧 听力原文

Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about urban heat islands, a phenomenon where cities 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. Additionally, waste heat from vehicles and air conditioners adds to the effect. One major consequence is increased energy consumption for cooling, which leads to higher greenhouse gas emissions. But there are solutions. Green roofs, which are covered with vegetation, can reduce rooftop temperatures by up to 40 degrees Celsius. They also improve insulation, reducing heating costs in winter. Another approach is increasing urban tree cover, which provides shade and cools the air through evapotranspiration. However, these measures require upfront investment and maintenance. Some cities, like Toronto, have implemented bylaws requiring green roofs on new buildings. So, while the problem is serious, there are practical steps we can take to mitigate it.