Today, in our environmental science lecture, we'll discuss the impact of urban heat islands. As cities grow, concrete and asphalt absorb and re-emit heat, making urban areas significantly warmer than surrounding rural regions. One effective mitigation strategy is increasing green spaces, such as parks and green roofs. Studies show that a single tree can cool its immediate area by up to 5 degrees Celsius. However, the most cost-effective method, surprisingly, is painting rooftops white to reflect sunlight. This can reduce cooling costs by up to 20% in hot climates. So, while trees are beneficial, white roofs offer a more practical solution for large-scale application.