All eyes were on Maricopa County, Arizona, last month as election officials were counting every vote. But in the meantime, another group has been busy counting every tree.
Trees bring enormous benefits to the communities where they grow. For example, they scrub pollution out of the air and counter the urban heat island effect — in some cases lowering ambient air temperatures by up to 9 degrees. Having trees nearby can potentially help homeowners save on energy bills and prevent excess mortality from heat waves.
However, these benefits are not equitably distributed among communities.
“A map of tree cover in virtually any city in America is also effectively a map of income and race,” said Jad Daley, president and CEO of the conservation nonprofit American Forests.
That’s why American Forests has been counting trees. As part of an effort to address nationwide inequities in tree cover, the group aims to assign “Tree Equity Scores” to cities and counties across the United States — beginning with three pilot sites, including Maricopa County.
The equity scores take into account a number of factors, from population density to the unemployment rate, to determine which areas would benefit most from tree-planting efforts.
American Forests hopes the project will help mitigate climate change, since trees suck carbon out of the atmosphere, while also combating systemic inequalities.
“If your goal is health equity, if your goal is climate justice, this is a roadmap that is going to get you there,” Daley said.
As defined by American Forests, neighborhoods achieve “Tree Equity” when they have enough canopy cover for residents to reap the health, economic, and other benefits that trees provide. To calculate progress toward this goal, American Forests begins by setting a target for each parcel of land — an ideal number of trees based on the natural environment and the area’s population density.
Then, satellite data helps them figure out the “canopy gap,” the difference between the ideal number of trees and the number that is already there.
Finally, they add information about race, age, income, unemployment and temperature, creating a filter that highlights which neighborhoods policymakers should prioritize.
Currently, the organization has neighborhood-by-neighborhood Tree Equity Scores for three test regions: Maricopa County, the San Francisco Bay Area, and the state of Rhode Island.
Daley said he hopes to expand the tool to all urbanized areas by 2022, covering land where 70 percent of the U.S. population lives.
Joseph Winters writes for Grist, an online environmental magazine. The original story appeared online here.
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