Lebanon group sees hot spots as a reason for trees

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    Lebanon residents, from left, Elise Weale, 7, Hunter Banker, 12, and Emily Chapin perform 30-second exercises during the Carter Community Building Associations "Fun Fitness in the Park" at Colburn Park, in Lebanon, N.H., on Tuesday, July 31, 2018. (Valley News - August Frank) Copyright Valley News. May not be reprinted or used online without permission. Send requests to permission@vnews.com. August Frank

Valley News Staff Writer
Published: 5/18/2022 10:19:52 PM
Modified: 5/18/2022 10:18:06 PM

LEBANON — When temperatures climbed into the 90s in the middle of May, Charlie DePuy took out his pocket laboratory and garnered data in his neighborhood. He could feel the hot day get hotter as he walked from Colburn Park to the surrounding parking lots. Sure enough, he recorded a 10-degree temperature spread. Once the trees are leafed out more fully, he expects the difference to be even more extreme.

DePuy, a member of the new Lebanon Tree Advisory Board, initiated one of its first projects: Mapping heat islands across the city and planting trees to cool them down. The Tree Advisory Board sees these pockets of extreme heat as a public health problem and one that does not affect everyone equally.

“Mechanic Street and Hanover Street and other quarters of the city — they beg for trees,” DePuy said.

Heat islands, also known as extreme heat micro-environments, get the most attention in dense urban centers, but they are also a problem in more rural communities, said Elizabeth Doran, a research assistant professor at the University of Vermont, where she is leading a research project on the issue across Vermont.

Wherever asphalt and concrete dominate the built environment and trees are scarce, temperatures are higher, she explained. Asphalt and concrete absorb heat throughout the day. At night, they slowly release their heat, nudging up the temperature. Trees not only offer cool temperatures wherever they cast their shade, but they also absorb energy from the sun to heat water into water vapor as they photosynthesize. That heat would otherwise heat up the neighborhood.

Doran and her research team have mapped extreme heat micro-environments in Burlington, and now they are expanding the project to 10 communities across the state.

New England will never get as hot as regions further south. But a heat wave coming on the heels of winter weather comes with its own risks, Doran said.

“We’re all of a sudden thrust into a May heat wave, where it’s in the 80s and low 90s. And people’s bodies, physiologically, are just not ready for that at all,” she said, adding that heat waves are most dangerous in May and June.

Two age groups — active young people between 18 and 24 and the elderly — are most vulnerable to extreme heat, Doran said. The young are active, and a bike ride that is enjoyable at 50 degrees can be dangerous at 90. Meanwhile, many who are older have pre-existing conditions that heat exacerbates, or they are bound to homes where they do not have air conditioners.

At 80, DePuy knows that he feels the heat more than he used to. DuPuy also said the Tree Advisory Board will analyze whether heat pockets are more common in low-income neighborhoods.

“Some populations are especially vulnerable to effects of extreme heat,” said Mary Maxfield, who also serves on the board.

Lower-income people are less likely to afford backup generators. Already struggling to pay for the energy to heat their homes, many cannot afford to cool their homes. And their homes are less likely to be well-weatherized to keep hot weather outside, she said.

Giving people air conditioners is the quickest way to help them through a heat wave, Doran said. But relying on air conditioners is risky.

“Rolling blackouts during extreme heat are not actually that unusual of a scenario that you could imagine would happen when there’s huge burdens on the electrical grid,” Doran said. The Tree Advisory Board is also well aware of this risk.

Then no one’s air conditioner will work unless they can afford backup energy or make their way to a cooling center equipped with generators.

“Our approach is to plant trees, not to put in more diesel generators,” DePuy said.

And there are more ways to reduce heat without relying on air conditioners. New Englanders may adopt the habits of warmer regions, such as pulling down blinds and closing windows in the morning and then opening them to let in the cool night air, Doran said.

Changing how we build matters, too. Reducing the mass of concrete in our sidewalks by pouring them 2 inches thick rather than the standard 4 inches, for example, will cut how much heat they will absorb. And permeable pavements also help, in part because they mimic how trees absorb heat to evaporate water, Doran said.

This summer, the Tree Advisory Board hopes to work with volunteers, including Lebanon High School students, to map temperatures across the city with pocket laboratories. They hope that their data will show city officials the need to plant more trees.

Claire Potter is a Report for America corps member. She can be reached at cpotter@vnews.com or 603-727-3242.

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