Today in our environmental science lecture, we'll discuss urban heat islands. Cities tend to be warmer than surrounding rural areas because buildings and roads absorb and re-emit heat. One surprising factor is the role of green spaces. Parks with trees can reduce local temperatures by up to 5 degrees Celsius. However, the effect is not uniform. The cooling impact depends on the size of the park and the density of tree cover. For instance, a small garden with scattered trees may only cool by 1 degree, while a large forested area can significantly lower surrounding temperatures. Planners should prioritize larger green corridors rather than many small patches.
❓ According to the lecture, what is the key factor for green spaces to effectively reduce urban temperatures?
A. A. The number of parks in the city
B. B. The size and tree density of the green space