Today in our environmental science lecture, we'll discuss urban heat islands. A recent study in Melbourne compared temperatures in the city center with those in surrounding parks. The researchers found that on hot summer days, the city center could be up to 4 degrees Celsius warmer than nearby green areas. This is because concrete and asphalt absorb and re-emit heat, while trees provide shade and release moisture through transpiration. Interestingly, the study also showed that even small community gardens can reduce local temperatures by about 1.5 degrees. However, the effect was strongest when green spaces were connected, forming corridors that allow cool air to flow through the city.