Study Maps Urban Heat Islands with Focus on Environmental Justice

State of the Planet

By: Jeremy Hinsdale

Floods, tornadoes and hurricanes cause deaths every year, but when it comes to weather-related fatalities, extreme heat is America’s deadliest killer. And the mercury is rising due to climate change: unprecedented heatwaves killed hundreds across Western North America this summer, making it one of the deadliest on record.

It may come as no surprise to most people that urban areas suffer more from extreme heat. Buildings, roads, and infrastructure all absorb, and re-emit, more of the sun’s heat than natural landscapes. Combine a dense built environment with heat generated by human activities and you soon begin to see urban heat islands – inner-city zones where temperatures can be as much as 20 degrees F warmer than surrounding, vegetated areas.

Scientists have documented the urban heat island effect since the 1800s, but the details of exactly why, where, and how much surface temperatures vary within individual cities is less well understood.

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