One out of every three days this summer has reached 90 degrees in central Pennsylvania, a sign of more intense heat related to climate change.
In cities, sidewalks and roads retain heat and can make afternoons even hotter – something called the urban heat island effect. Cities like Harrisburg, Lancaster, and York are planting trees as one way to try to check the escalating temperatures.
But there can be obstacles to that solution.
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On a recent Tuesday along Market Street in downtown Harrisburg, a few blocks east of the Susquehanna River, everyone had somewhere to be.
Rays of sun chased walkers down sidewalks, through alleyways crowded with brush, and the world became a squint of white concrete and roadside bodegas.
“A lot of these houses, they don’t have, like, roof fronts, so they don’t get a lot of shade,” Gary Lewis said. “The trees kinda help that. In the summertime, anyway.”
Lewis has lived in Harrisburg for almost five years, and he walks to work down Market every day.
As much as he can, he sticks to the shade–like others on Market on a day where the temperature was headed to 91.
Harrisburg’s forestry department recently planted 86 street trees in three neighborhoods as part of a grant-funded project. According to the Arbor Day Foundation, in one year, a mature tree will absorb about 48 pounds of carbon dioxide from the atmosphere.
So, Harrisburg’s new trees will consume over 4,000 pounds of CO2 when they mature. Sounds like a lot at first, but to put it in context, that consumption would scratch less than seven ten-millionths of a percentage off of Pennsylvania’s total emissions.
Added benefits of trees
But trees do more than absorb carbon dioxide. The Pennsylvania Department of Conservation and Natural Resources says community trees filter stormwater, cool down hot days with shade, and prevent flooding. And, one large tree can provide a day’s supply of oxygen for up to four people.
The US Forest Service has even found, as tree cover increases, crime can decrease.
Tisha Barber and her students are picking up trash along Market Street as a part of Harrisburg Housing Authority’s Environmental Teen Corporation. They’d love to have more trees added to the area.
“Can’t go wrong with planting trees!” Barber says.
From an economic standpoint, trees increase property value by up to 15% and can save people 3% on their energy bills, the Arbor Day Foundation says.
But there are still disadvantages to planting trees along city streets.
For one, there’s the cost.
The City of Lancaster says planting one street tree can cost between $165 and $230 (including labor costs).
Homeowners can apply for grants from the city, but funds are limited. Those over 65 and low-income families can also apply for financial assistance.
And if a tree’s roots buckle a sidewalk or interfere with sewer lines, a homeowner will have to pay to have it removed and to repair any damage.
That can cost thousands of dollars.
And many cities, including Harrisburg and Lancaster, require property owners to have a permit to remove or plant street trees. They also restrict the size and type of tree planted. City officials say that potential expense can make people hesitant to plant trees.
Some people have taken to shaving the concrete or installing concrete wedges as short-term solutions available at lower costs.
When the tree’s roots are fragile, The Bartlett Tree Research Laboratory says, contractors can try sidewalk bridging. Sonotubes–peelable Pillsbury cinnamon roll cans used to shape concrete–create columns along the path of the sidewalk to hold up the walkway and allow for root growth.
Some people even swear off tree planting because it’s too costly and disruptive.
Kathy Ford lives about a mile away from where Lewis walks to work, over by Primrose and North 17th streets. The city financed street tree planting in her neighborhood, just two blocks from where she had to remove her own trees because of damage they’d done to her sidewalk.
It cost $3,000, she said. “Then I had to have my concrete done all the way over because it left it all cracked. You see the lady’s [sidewalk] right there? Can’t afford to get it fixed.”
Ford gestures toward the asphalt that her neighbor poured between two uneven slabs of concrete, creating a makeshift ramp.
“They shouldn’t’ve planted them trees there. You know why? Because we had to take ours up. See what it does to the sidewalk after years?”
“If somebody trips on your sidewalk, whose insurance? You’re liable,” Ford said, laughing.
Working around problems
But for some people, these trees are their lives.
Cody Kiefer stands amid a neighborhood of houses with wide windows, red brick, white trim, and doric columns.
Lancaster City appointed Kiefer its Urban Forester back in September 2021, and since then, he’s worked closely with engineers to put together individualized sidewalk projects intended to meet the needs of both the city and the property owners.
He points out the pink, white, and orange spray paint tattooing the concrete slabs, some pushed up by tree roots and others just badly maintained. The city cited these areas for sidewalk rerouting and replacement, gas line repair, and water line repair.
He says they have to consider a lot more than just the homeowner when uprooting and planting new trees streetside.
“In reality, we have varying rights of way around the streets,” Kiefer said. “And so, if we’re really wanting to put in street trees, we need to stop planting them in a two-foot or three-foot-wide strip like this. We need to push the sidewalks to the furthest extent in the right-of-way as we can to provide maximum room here.
“The best solution to this issue is giving the tree more room.”
Rerouting sidewalks is usually the best choice for homes with a little more space to spare between the street and the home’s “right-of-way,” he said.
It also allows for a ton more water to soak into the ground instead of running down streets, escaping into sewage tunnels, and making its way into drinking water.
“We’re talking possibly 30, 40 percent of a rainfall event–a typical, average rainfall event–can be absorbed in the area directly beneath a tree canopy… That’s gallons and gallons – at a tree level – of rainfall that’s not reaching the ground. It just evaporates back up into the atmosphere. So, aggregating that across the city level is not insignificant.”
But row houses in many neighborhoods can’t afford to lose any extra space. Most don’t even have that extra space to begin with. For those homes, Kiefer recommends smaller planter boxes with flowers and ferns to refresh the city’s urban landscape.
Part of the reason that actual forests reduce heat island effects, Kiefer said, is the combination of large trees and small plants and brush.
“That’s what Philadelphia did in some of their lower income neighborhoods… By increasing some plants through planters in those neighborhoods, what they’ve seen is people really began to take ownership of those and saw the potential for their community and their streets,” he said.
Kiefer said studies have connected urban forests to things like reduced hospitalization rates, increased recovery times, reduced instances of childhood asthma, and equity in academic performance.
Drea Mitchell understands where Kiefer is coming from.
Back on Market Street, Mitchell sits and admires her slice of Harrisburg. The hardwood in front of her home is so large, it shades her neighbor’s house, too.
“Oh yeah, my shade–I love it,” she said.
“You get a plus one and a minus, also. So you get the shade, but you get the little creatures that come with it. But I can’t complain; I’ll take the creatures.”
Across the road, there’s a plot of land converted into a prayer garden with grass, flowers, and bushes, a couple feet behind the new street trees.
“I’ve seen people go down there,” she said, smiling. “They sit, and, you know, it’s like a garden of paradise.”
So, the midday sun beat down. Except, on that strip of Market Street, not on cement, but on plants and soil.