Can you explain the urban heat island effect?

urban heat island nyc — These images from the NASA/USGS satellite Landsat show the cooling effects of plants on New York City’s heat. On the left, areas of the map that are dark green have dense vegetation. Notice how these regions match up with the dark purple regions—those with the coolest temperatures—on the right. Credit: Maps by Robert Simmon, using data from the Landsat Program. Learn more at NASA's Climate Kids.

While urban areas are typically warmer than the surrounding rural areas, the urban heat island effect doesn't significantly impact overall global warming. This is because scientists have taken it into account when measuring temperature changes.

Urban heat islands are not a recent discovery. Weather watchers using basic mercury thermometers have observed that cities tend to be warmer than the nearby countryside for nearly two centuries.

Moreover, researchers have noticed that the intensity of these heat islands can differ from city to city. However, they can separate these localized effects from the broader, long-term climate trends. In the grand scheme of things, the urban heat island effect hasn't played a substantial role in global warming. The primary culprit remains other human activities, especially the burning of fossil fuels."

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NASA's Climate Kids: What Is an Urban Heat Island?
Climate Change and Heat Islands (U.S. EPA)