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B.C. expected to dodge emerging climate change problem tied to tree planting

Trees combat climate change, but can also lead to the warming albedo effect
Much of B.C.’s tree planting program so far has been replacing harvested trees, which minimizes the albedo effect. THE CANADIAN PRESS/Jonathan Hayward

The province’s tree planting program should be safe from a climate phenomenon which in some cases has led to newly planted trees warming local climates.

The albedo effect is the way of measuring the proportion of sunlight and energy that is reflected back into the atmosphere by the Earth. How much is reflected back changes depending on what’s on the ground. Snow has high albedo, meaning it reflects back a lot of sunlight. Tree cover has lower albedo, and that can vary depending on the kinds of trees and the colour of the leaves. So if lots of darker trees are planted, they will absorb more energy, cutting into the cooling benefit the trees are intended to have (trees capture carbon dioxide, which helps lessens global warming.)

In some locations, the albedo effect is so prominent, that areas surrounding where trees have been planted are reportedly warmer than they were before. An article published by the Yale School of Environment said that some researchers who had studied the impact the planting of the Yatir Forest in the Negev Desert in Israel found that the forest actually made the area warmer, rather than cooler, because the dark-leaved trees were capturing more solar energy than the sands of the desert had previously.

But Werner Kurz, a senior research scientist with Natural Resources Canada, who works with the Canadian Forest Service, said the albedo effect is more damaging to climate cooling efforts when trees are planted in places where they weren’t before, like a desert.

B.C.’s tree planting program, which has seen a billion trees planted since since 2018, mainly focuses on replanting harvested trees. That means areas that were already forested are now being recovered with forest, so the albedo effect should have a minimal impact, according to Kurz.

“I think it’s important to state that tree planting is climate effective. With the time horizon in mind, obviously a tiny little seedling doesn’t take up a lot of carbon. But over time, they take up more and more.”

Kurz said a number of other factors aren’t considered currently that could cancel out the albedo effect, such as organic compounds and moisture which trees naturally release, can have a cooling effect.

A spokesperson for the forestry ministry said while they are “aware of the study of albedo effects of forest cover, our focus is on the care for B.C.’s forests.”

Kurz said there are ways to combat the albedo effect, while still planting trees – plant trees with lighter coloured foliage and faster growing, so carbon-capturing benefits occur more quickly.

READ MORE: Only 8.5 million of the two billion trees promised by PM have been planted so far


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