Today, in our environmental science lecture, we'll discuss urban green spaces. Recent studies show that parks and community gardens can reduce city temperatures by up to 5 degrees Celsius during heatwaves. However, the key factor is not the size of the green area but its distribution. For example, many small green spaces scattered across a city are more effective than one large park, because they provide cooler routes for pedestrians and improve air flow. Additionally, green roofs on buildings, though smaller, contribute significantly by absorbing rainwater and reducing runoff. Yet, their maintenance costs are higher than ground-level parks.
❓ According to the lecture, what is the most important factor for reducing city temperatures?