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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. One major cause is the replacement of natural surfaces with materials like asphalt and concrete, which absorb and re-radiate heat. Another factor is the lack of vegetation, which normally provides cooling through evapotranspiration. But there are solutions. For instance, green roofs—covering rooftops with plants—can reduce surface temperatures and improve insulation. Also, increasing albedo, or reflectivity, by using lighter-colored pavements and roofs can bounce sunlight back into space. However, these measures aren't always easy to implement. Retrofitting existing buildings with green roofs can be costly, and changing road surfaces is a long-term project. So, cities often need to balance immediate needs with long-term sustainability. Now, let's consider a specific case: Los Angeles has been experimenting with cool pavements, but some residents complain the reflective surfaces make them feel hotter during the day. This shows that even well-intentioned solutions can have unintended consequences.