Today in our environmental science lecture, we're discussing urban green spaces. A recent study in Manchester found that adding parks and rooftop gardens can reduce city temperatures by up to 2 degrees Celsius during heatwaves. Interestingly, the cooling effect was strongest not in the largest parks, but in areas with many small, interconnected green spaces. This is because they create continuous corridors for air flow. However, the study also noted that trees near buildings can sometimes trap heat if not properly spaced. The researchers recommend a mix of grass, shrubs, and trees, with at least 30% of the area covered by shade to maximize benefits.