Student sample for assessment
Written by a Year 7 student in Footscray, Victoria, Australia.
Have you noticed that your neighbourhood feels warmer on summer nights than the countryside outside the city? That difference is an urban heat island. Cities are typically two to five degrees warmer than surrounding rural areas, especially after sunset. This happens because cities are built differently from natural environments. Dark surfaces like bitumen roads and concrete absorb and store heat from the sun much more effectively than vegetation does. While a park or farm reflects some heat back into the atmosphere, a street absorbs it and releases it slowly throughout the night. Understanding why heat islands form helps us see why they are a problem. During the day, these dark surfaces act like giant heat collectors. At night, they release all that stored energy, making cities uncomfortable and driving up demand for air conditioning. This creates a cycle where more people use more electricity, which generates more heat and pollution. Trees and green spaces break this cycle because they provide shade and release moisture through a process called evaporation, which naturally cools the air around them. Melbourne and Sydney have both measured this effect and found that green spaces can reduce local temperatures significantly. Fortunately, cities have several ways to fight heat islands. Planting more trees and creating parks obviously helps, but some solutions are more surprising. Light-coloured road surfaces reflect heat rather than absorbing it, and some cities are testing these alternatives. Building green roofs covered in plants is another emerging solution that reduces the temperature inside buildings and contributes to cooling the surrounding area. The most effective approach combines several strategies: more vegetation, lighter surfaces and better urban planning. By understanding how cities create their own heat, communities can make choices that benefit both residents and the environment.