Heat waves meet "heat islands"
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As dangerously high temperatures hit much of the U.S. this summer, a new analysis finds urban "heat islands" significantly exacerbate such extreme weather.
Why it matters: A stifling, widespread heat wave is bringing some of the hottest and most perilous temperatures of the summer to more than 40% of the U.S. population this week.
Furthermore, urban heat islands (UHIs) are boosting temperatures within 65 major U.S. cities, according to a recent Climate Central analysis.
- Nearly 34 million people live in environments where UHIs could raise temperatures by at least 8°F.
How it works: Heat islands — urban hotspots with higher temperatures compared to surrounding areas — are created when roads, buildings, parking lots and so on "trap" heat.
- Often such neighborhoods, which tend to be poorer, lack trees and plants that would otherwise help cool the area.
Zoom in: More than 5 million people in New York City, Chicago and San Francisco, for example, live in environments where UHIs can amplify summer temperatures by at least 10°F, according to Climate Central, a nonprofit climate research group.
- In cities with sprawling heat intensity, such as Houston, high UHI index values are spread across a vast developed land area.
What they're saying: "Urban heat islands already expose residents to disproportionate heat risks and cooling costs, which will only climb as long as carbon pollution drives up global temperatures," Climate Central's Jennifer Brady said in a statement.
- "The entire planet is warming due to human-caused climate change, but the built environment further amplifies both average temperatures and extreme heat in cities," per the analysis.
Caveat: Scientists factor the heat island effect into their climate change monitoring and projections, and it does not explain the sharp uptick in global average temperatures, melting glaciers, record ocean warmth and more.
The bottom line: Cities are increasingly understanding the need to combat the heat island effect by adding more green space, using reflective paint on roads and buildings, opening cooling centers and more.
- But their efforts may not be going far enough, as Jennifer has reported.
