Planting Trees Can Combat Effects Of Urban Heat Island, Climate Change Trees are one of the best ways to fight deadly urban heat, but U.S. cities lose millions every year. And many low-income areas are starting at a disadvantage.

Trees Are Key To Fighting Urban Heat — But Cities Keep Losing Them

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We told you yesterday that low-income areas of major U.S. cities are often hotter than wealthy neighborhoods. It's the finding of an investigation from NPR and the Howard Center for Investigative Journalism at the University of Maryland.

Today we look at one of the best ways to beat the urban heat - trees. American cities are losing nearly 29 million trees every year. Many are struggling to reverse that trend. That includes Louisville, Ky., which, compared to its surroundings, has been getting hotter faster than any other U.S. city. NPR's Meg Anderson reports.

MEG ANDERSON, BYLINE: Annie Haigler is walking down her block in Park DuValle, a lower-income neighborhood on Louisville's west side. It's lined with single-family homes and well-kept, tidy yards.

ANNIE HAIGLER: First of all, this is my neighborhood, and I love it, even without the things that I would want to have here.

ANDERSON: Things like trees. She points to a small, scraggly one in the grassy patch running down her street.

HAIGLER: That's the median right there. They've got a tree in there, but it's one tree.

ANDERSON: There's another small tree behind it, and there are parts of this neighborhood with more trees. But overall, data shows the canopy here is about half the city average. Haigler says she thinks trees were just not a priority. Park DuValle used to be the site of a massive public housing complex. That was demolished, and construction started here in the late 90s.

HAIGLER: So after 20 years, if we had thought differently about the design, we might have put more trees here.

ANDERSON: Across Louisville, wealthier neighborhoods have as much as twice the tree coverage as low-income areas, many of which are communities of color.

Jad Daley is president and CEO of the nonprofit American Forests. He says that pattern is often the case nationwide.

JAD DALEY: If we show you a map of a tree canopy in virtually any city in America, we're also showing you a map of income. And in many cases, we're showing you a map of race and ethnicity in ways that transcend income.

ANDERSON: Trees aren't just pleasant; they're key to fighting heat.

DALEY: If you live in an area in cities that's seeing more extreme heat days but you don't have tree cover to cool down your neighborhood, that can literally be a life-or-death issue.

ANDERSON: According to an analysis by NPR and the Howard Center, low-income areas of cities across the country tend to be hotter than their wealthier counterparts. Those areas are hotter, in part, because they often have fewer trees. And that heat can take a toll on health. Here's Daley.

DALEY: The folks who are least likely to have air conditioning to weather heat waves, the folks who are most likely to have preexisting health conditions that put them at greater risk from those heat waves aren't getting the benefits of trees.

ANDERSON: Between 2009 and 2014, 44 states lost tree cover in urban areas, according to the U.S. Forest Service. And when it comes to trees, many low-income areas are already starting at a deficit.

Ked Stanfield, executive director of Louisville Grows, a nonprofit that plants trees, says it doesn't have to be that way. He took me to St. James Court in Old Louisville. It's a boulevard famous for its stately Victorian homes and an annual art fair. But we were there to see the huge, lush canopy towering over us.

KED STANFIELD: If you were to look at an aerial view of this, it wouldn't look too dissimilar from a forest.

ANDERSON: The trees shade us almost completely. Stanfield says it's a reminder of what's possible if trees are part of the plan from the beginning.

STANFIELD: For anybody that plants trees in a city, this is the goal. This is the dream. This is what you hope to create in these cities.

ANDERSON: But even if trees are in the plan, maintaining them takes money - a lot of money. This year, tree maintenance on this street, which is about a quarter-mile-long, will cost around $20,000, according to the neighborhood association.

The city has planted and donated roughly 5,000 trees annually since 2013, but it loses about 54,000 every year, according to its own assessment, to invasive species, natural disasters and urban development. And Louisville is facing a $35 million budget deficit. They've cut funding to emergency police and fire services. Mayor Greg Fischer says he'd like to plant more trees...

GREG FISCHER: But we've got to wrestle with this great American challenge, right? People want everything, but they don't want to pay for anything.

ANDERSON: When it comes to planting tens of thousands more, he says...

FISCHER: City government's not going to be able to do all that by itself.

ANDERSON: He's counting on nonprofits and other institutions to fill in the gaps.

At the University of Louisville's Envirome Institute, researchers are trying to make the case that trees are a must-have in city budgets. They're starting a study called the Green Heart Project and will plant full-grown trees as tall as 30 feet in a 3-square-mile area in Louisville. The five-year study will measure how the health of hundreds of participants changes and compare them to a nearby control group. In short, they're testing trees the same way you test a new drug.

ARUNI BHATNAGAR: The idea was to run this whole project as a clinical trial, but instead of giving pills, we plant trees.

ANDERSON: Aruni Bhatnagar is director of the institute. And he says, beyond cooling a city down, studies have linked trees to much more - better air quality, better stormwater management, lower energy costs, lower levels of stress, even a longer life. But Bhatnagar says you can't always isolate trees as the reason those things happen.

BHATNAGAR: Everything remaining the same - now they put trees in it. What happens?

ANDERSON: He says cities have divorced themselves from nature, and now he wants to show what happens when you put nature back in.

Meg Anderson, NPR News.

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