Vegetation shades the land in rural areas, allowing it to stay cool and moist. Urban development causes these natural environments to be replaced with roads, buildings, and other dry, man-made surfaces that retain heat. Therefore, urban areas usually have higher temperatures than the surrounding rural regions. Several environmental impacts from this “heat island effect” are listed below.

  • Increased energy consumption due to increased electricity demand for air conditioning.
  • Increased greenhouse gas emissions from power plants due to the increased electricity demand.
  • Decreased water quality due to heated rooftops and pavement elevating the temperature of storm water running off of them and into local water bodies.

Communities can mitigate these effects through landscape ordinances, incentive programs, urban forestry efforts, and other green infrastructure practices. Examples of these techniques implemented across the United States can be found in the Community Actions Database maintained by the U.S. Environmental Protection Agency.

For example, a 33,000-square foot green roof on the Milwaukee Public Library has prevented 2.8 million gallons of storm water from entering the storm sewer system since its installation.

The City of Chicago has also taken action by repaving alleys with permeable pavement, installing green roofs and landscaped medians throughout the city, and implementing a Sustainable Backyards Program to partially reimburse citizens for installing trees, native plants, rain barrels, etc.

Learn more about what communities and individuals can do to reduce the heat island effect here.

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About the Author

Marueen Schneider

Maureen A. Schneider
Project Engineer

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