Nghe TOEFL

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Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to discuss a concept called 'urban heat islands.' This refers to the phenomenon where cities are significantly warmer than surrounding rural areas. The main cause is the replacement of natural surfaces, like soil and vegetation, with materials that absorb and retain heat, such as asphalt and concrete. Buildings and roads also block wind, reducing cooling. Additionally, human activities—like driving cars, running air conditioners, and industrial processes—release waste heat. Interestingly, the temperature difference can be as much as 10 degrees Fahrenheit on clear, calm nights. This effect has serious implications. For example, higher temperatures increase energy demand for cooling, which leads to more greenhouse gas emissions. Also, heat-related health problems become more common, especially among vulnerable populations. To mitigate this, cities are adopting strategies like planting trees on streets, creating green roofs, and using reflective materials for pavements. So, while the problem is complex, there are practical solutions being implemented.