Today in our environmental science lecture, we'll discuss urban heat islands. As cities grow, concrete and asphalt absorb sunlight and re-radiate heat, making urban areas warmer than surrounding rural regions. One key factor is the lack of vegetation. Trees and green spaces provide shade and cool the air through evapotranspiration. A study in Melbourne found that increasing tree canopy by 20% could reduce peak summer temperatures by up to 4 degrees Celsius. Additionally, using reflective materials on rooftops and pavements can lower heat absorption. However, the most cost-effective solution remains planting more trees, especially in densely built neighborhoods.