The Inequality of Urban Tree Cover

Last month, the Washington Post conducted its own study of the city's tree canopy, with some findings that may not surprise anyone who lives in the capital: Lower-income neighborhoods were substantially less likely to have trees, with the city's densest greenery clustered west of the 16th Street Northwest fault line that divides some of Washington's wealthiest neighborhoods from the rest of town. Tree density in Washington, in short, provides a kind of proxy for wealth (and if you've spent time in Washington, you also know that wealth is a proxy for race).

Lest other cities scoff at Washington's arbor-inequality, research just published online in the journal Environmental Health Perspectives confirms that a very similar pattern appears all across the country. Researchers from the University of California at Berkeley looked at 63,436 census block groups from across the country covering 304 metropolitan areas and more than 81 million people. And they identified those blocks most at risk in extreme heat waves thanks to the lack of tree cover or the presence of too much asphalt (or impervious surfaces). Both of these factors have been shown to exacerbate the urban heat island effect, raising surface temperatures, suggesting that people who live in these neighborhoods may be at the highest heat risk as temperatures warm with climate change.