The secret ingredient in Biden’s climate law? City trees.

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You’ve probably heard that the Biden administration’s signature climate law, the Inflation Reduction Act, gives people big rebates and tax credits to switch to a heat pump or electric vehicle. But the law also contains a much-less-talked-about provision that could save lives: $1.5 billion for planting and maintaining trees that would turn down the temperature in many American cities.

That money goes to the U.S. Forest Service, which has been doling out the money to hundreds of applicants, including nonprofits and cities themselves. The $1.5 billion is nearly 40 times bigger than what the Forest Service typically budgets for planting and taking care of trees in cities each year, and it’s earmarked for underserved neighborhoods. So far, the agency has awarded $1.25 billion of the funding, and is working to distribute the remaining over the next year.

“Going from a $36 [million] to $40 million program with urban forestry, to a little over $1.5 billion, was a substantial infusion in dollars to address things like tree equity, tree canopy, and more importantly, providing this type of funding to underserved communities,” said Homer Wilkes, undersecretary for natural resources and environment at the U.S. Department of Agriculture.

While cities across the U.S. already run their own tree-planting programs with their own funds, this amount of federal money is like winning the arborist lottery. “It’s unprecedented,” said Edith de Guzman, a researcher at UCLA and director of the Los Angeles Urban Cooling Collaborative, whose research has found that tree cover significantly reduces heat-related hospitalizations. “This is a pinch yourself, once-in-a-lifetime kind of opportunity.”

Planting trees in cities, though, turns out to be a surprisingly complex challenge. Some species like live oak grow bigger canopies, which provide more shade. Others, like fruit trees, can provide food. Along a noisy street, residents might want bushier trees that better block sound. And all tree species capture carbon and clean the air by hoovering up pollutants. Any green space also reduces urban flooding by soaking up rainwater.

With the IRA money, arborists will try to plant native tree species adapted to the local environment. “The native species here are going to do best with our climate, but also provide so many more benefits for pollinators,” said Jordan Herring, arborist and ground maintenance manager for the city of Winchester, Virginia, which received some IRA funding. “Birds, small mammals, they’ve adapted with these species for so long.”

But just because a species is native doesn’t mean it’s perfect for a given spot. Some species have deeper root systems while others stay closer to the surface, potentially cracking sidewalks and creating problems for residents in wheelchairs. So some of the IRA funding will also go toward planting trees in private property, like around homes, apartment buildings, and businesses. In San Francisco, for example, native species like the coast live oak and California buckeye, both of which would tear up sidewalks if planted on a street, would work nicely in a private lot. “It allows us to respond to a very common desire in the community of somebody saying: I really don’t want a tree in front of my house on the sidewalk, but I would love one in my backyard,” said Brian Wiedenmeier, executive director of Friends of the Urban Forest, another organization that received money from the legislation. 

Any urban arborist will tell you they can’t do their job properly without taking into account what a neighborhood wants. “We can’t just parachute into any of these neighborhoods and say: Lucky you — we’re here to plant trees,” said Dan Lambe, chief executive of the Arbor Day Foundation, which received $50 million of IRA funding from the Forest Service to divvy out to nonprofits, cities, and tribal communities. “It takes relationship-building.”

Port St. Lucie, Florida, which also received a share of the IRA funds, holds citizen summits where residents hash out what kinds of tree species they want, and where they want them planted. They also get updates on projects completed since the previous year’s summit. “So residents get to actually see the improvements and the input that they’ve made, and the changes they’ve been able to make in the community,” said Shereese Snagg, project coordinator of urban beautification in the city’s public works department.

Perhaps the greatest challenge for an urban tree is the same for any urbanite: City life can be tough. When choosing species, arborists consider that some need more light than others, and will wither if a building is blocking the sun. If a canopy grows too big, it might get tangled up in overhead wires and electrocute itself, so pruning is paramount. All the while, trees may get stressed by ever-hotter temperatures and less rainfall made worse by climate change, meaning arborists need to look into the future to find the right species to plant. 

If one species is hardy and easy to care for in a particular city, the temptation for an arborist is to just plant them all over the place. But that lack of diversity would mean they’d all reach the end of their lives at once and need to be ripped out en masse. “If you throw in a pest or disease in with that, you have a serious situation on your hands, trying to remove a lot of trees before they die completely,” said Herring. “So one of my biggest pushes is also getting a lot of diverse species out there into the mix.”

Just being a native species, though, is no guarantee that a tree will survive. For the first year or so of its life, a tree needs regular watering until its roots get established. Sick-looking youngsters will need caring for, and as they grow they’ll need pruning to make sure they turn into a manageable form. Accordingly, the Forest Service stipulates that the IRA cash goes toward both planting and maintaining. “We didn’t just give these grants and turn them loose,” Wilkes said. “This will be a process that will actually be worked on and monitored over the next five years to make sure that the American people are getting what they’re paying for.”

Even longer-term, the federal funding could help solidify a sort of information-sharing network of arborists. The idea is to develop a nationwide workforce of folks who can select, plant, and maintain the urban forest for years to come. Especially in underserved neighborhoods, that could provide jobs while preparing a city for a hotter future. “I think trees can sometimes be seen as a nice-to-have in a must-have world,” Lambe said. “But what we’re learning through science and otherwise is that trees are no longer a nice-to-have. They are a critical part of city survival.”