Urban heat islands: You likely live on one

Urban heat islands result in significantly higher temperatures in cities, where most of the population lives. Here’s how they work.

An urban heat island is a phenomenon where cities and towns are significantly warmer than their surrounding rural areas. This happens because urban areas have dense concentrations of buildings, roads, and other surfaces that absorb and retain heat more effectively than natural landscapes like forests and fields. As a result, temperatures in cities can be several degrees higher, especially at night.

Urban heat islands occur because of how cities are built and operated. Buildings, pavement, and other man-made structures absorb heat during the day and release it slowly at night, keeping temperatures elevated. Additionally, the lack of vegetation in urban areas reduces shade and the natural cooling effect of evapotranspiration, where plants release water into the air. Cars, factories, and air conditioners also contribute to higher temperatures by emitting heat as they operate.

The urban heat effect has been shown to result in more intense and longer-lasting heat waves, poor air quality, and increased energy consumption as residents try to cool their homes.