WARMING TREES: Northland foliage causing warmer winter temperatures

Published: Feb. 22, 2023 at 12:57 PM CST
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DULUTH, MN. (Northern News Now) - Native trees to northeastern Minnesota could be causing warmer temperatures than the rest of the state.

Coniferous trees, or trees that don’t lose their needles in winter, trap in light that turns to heat.

Those trees make the landscape in northeastern Minnesota darker.

“There are a lot more conifers in this area. Southern Minnesota’s mostly prairies and then it transitions to hardwoods and more coniferous forests,” Jacob Busiahn, a certified arborist with Tettegouche Treecare, said.

Trees native to the Northland include Black Spruce, Balsam Fir and Red Pine.

Those trees tend to keep their leaves in winter.

“Coniferous trees are gonna hold on to its needles throughout the entire year, versus a deciduous will leaf out every spring and then drop them in the fall,” he said.

Deciduous trees are ones that have bare branches in the fall and winter, making it harder for them to lock in heat.

Adam Lorch, Chief Meteorologist at Northern News Now, explains how the phenomenon happens.

“The sunlight comes in as UV light and hits the tree, the tree absorbs it and then reemits it as infrared heat,” Lorch said.

The name of the event Lorch described is called albedo.

Albedo is the amount of sun reflected on a surface, according to Lorch.

The darker trees make it harder to reflect light, unlike southern Minnesota where there are large areas of open land.

The Northern News Now weather team has to take into account that, on sunny days with no snow on the trees, they might have to adjust their forecasts.

“It’s kind of interesting because we’ll be forecasting and we’ll have to bump our temperatures up, up in northern Minnesota five, ten degrees just to account for this forestry type, Lorch said.

Northland winters may be cold, but the trees warm it up just a little bit.

“It just makes conditions better. It makes it nicer out, it doesn’t make it worse,” Lorch said.