Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about the concept of 'urban heat islands.' Essentially, cities tend to be warmer than surrounding rural areas because of human activities and the materials we use to build our infrastructure. Buildings, roads, and other structures absorb and re-emit the sun's heat more than natural landscapes like forests and water bodies do. For example, asphalt parking lots can reach temperatures much higher than nearby grassy fields on a sunny day. This heat is then released at night, keeping cities warmer. Additionally, waste heat from vehicles, air conditioners, and industrial processes adds to the effect. One major consequence is increased energy consumption for cooling, which in turn raises greenhouse gas emissions. However, there are mitigation strategies, such as planting more trees, using reflective roofing materials, and creating green spaces. These approaches not only reduce temperatures but also improve air quality and public health. So, while urban heat islands pose challenges, they also present opportunities for sustainable urban design.