What is an urban heat island, and what urban planning strategies can mitigate it?

• A. An urban area becomes cooler than surrounding rural areas due to built surfaces and activities.
• B. An urban area becomes warmer than surrounding rural areas due to built surfaces and activities; mitigation includes planting trees and reducing emissions.
• C. It refers to weather patterns in rural zones.
• D. Mitigation strategies include removing all trees and painting buildings black.

Answer: (D)

An urban heat island is when a city becomes warmer than surrounding rural areas because built surfaces like concrete and dark roofs absorb and retain heat, there’s more energy use, and there is less vegetation to cool the air through shade and evapotranspiration. This warming effect is most noticeable on hot days and often at night when the city holds heat longer. The best answer captures this warming due to those built surfaces and activities and names mitigation that targets both cooling and heat sources: planting trees and reducing emissions. Trees provide shade and release moisture, which lowers temperatures, while cutting energy use and pollution reduces heat release and absorbed heat. Additional strategies include increasing surface albedo with lighter-colored roofs and pavements, expanding green spaces, and using cool or permeable materials. The other statements don’t fit the concept: urban areas aren’t cooler than rural areas, urban weather isn’t defined by rural patterns, and removing trees plus painting buildings black would actually worsen heat.