Today, in our environmental science lecture, we're discussing urban green spaces. Recent studies show that city parks not only improve air quality but also significantly reduce the heat island effect. For instance, a park in Melbourne, Australia, lowered surrounding temperatures by up to 4 degrees Celsius during summer. However, the key factor is the density of trees, not just the size of the park. Grass areas have less cooling impact. So, when designing new green spaces, planners should prioritize planting a variety of native trees, which require less water and support local wildlife. This approach is both sustainable and cost-effective.