Aug 11, 2023 - Climate

Examining Greater Houston's heat islands

Illustration of a man leaning against a traffic post on a sidewalk with a light beaming down

Illustration: Sarah Grillo/Axios

About 73% of Houston-area residents live in an area where the "urban heat island" effect raises temperatures by 8° or more, per a new analysis by nonprofit climate research group Climate Central, Axios' Alex Fitzpatrick reports.

Driving the news: The analysis comes as Harris County records its ninth heat-related death since the beginning of the year, all of which happened since the start of this summer's detrimental heat waves.

  • The dead range from 20 to 89 years old, according to the Harris County Institute of Forensic Sciences.

Why it matters: Heat islands — wherein heat is trapped by heat-absorbing surfaces and structures — can make cities less livable and increase the risk of heat-related health complications.

  • They can also amplify the effects of already dangerous heat waves, like the one gripping an expanding part of the U.S. this week.

By the numbers: The Houston area has 4.3 million people living where heat islands create an 8° difference.

  • 269,000 of those people live where heat islands make things 9° hotter, while more than 30,000 live where it's 10° hotter.

Between the lines: Low-income neighborhoods tend to be more vulnerable to heat islands than wealthier ones, making this a key climate equity issue.

  • Heat islands can also lead to increased energy usage and costs as residents keep cool with air conditioning.

What's happening: Harris County Precinct 4 Commissioner Lesley Briones is working to plant 1,200 new trees in the underserved Alief community to help combat the high heat.

  • "Alief on average is 10° hotter than other parts of Harris County," Briones said when announcing the initiative in April. "This investment will help address the heat island that we are experiencing here in Alief."

The big picture: 41 million Americans live in urban areas where heat islands raise local temperatures by 8° or more, per Climate Central's analysis of 44 U.S. cities.

Of note: While the urban heat island effect is very real, it doesn't skew global climate data "because scientists have accounted for it in their measurements," per NASA.

Yes, but: Adaptation and mitigation can only do so much in the face of triple-digit temperatures lasting for days on end.

  • "Changes to the built environment can cool these neighborhoods, but until global temperatures stop rising, city residents will face increasingly steeper challenges to stay safe during periods of extreme heat," Climate Central senior data analyst Jennifer Brady said in a statement.

Methodology: For its report, Climate Central analyzed the influence of factors including surface heat absorption, the amount of tree cover, building heights and more on U.S. census tracts. Population estimates are based on 2020 census data.

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