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Listen to part of a lecture in an environmental science class. Today we’re going to talk about urban heat islands. As many of you know, cities tend to be warmer than surrounding rural areas. This is because concrete and asphalt absorb and re-emit heat from the sun more than vegetation does. But there’s a simple solution: green roofs. A green roof is a roof that is partially or completely covered with vegetation. It can reduce the surface temperature of a building by up to 40 degrees Fahrenheit in summer. How? Plants absorb sunlight for photosynthesis, and they also release moisture through transpiration, which cools the air. Additionally, green roofs provide insulation, reducing the need for air conditioning. But there are challenges. They are heavier and require structural support. They also demand regular maintenance. However, many cities are offering incentives, like tax breaks, to encourage their installation. So although the upfront cost is high, the long-term benefits—both environmental and financial—make green roofs an attractive option.