Back in 2004, when wildfires in Alaska burned an area the size of Massachusetts, Michelle Mack wondered just how much carbon had permanently moved from the landscape into the atmosphere.
Mack, an ecologist at Northern Arizona University, knew that the carbon dioxide released by these burning trees could further accelerate global warming. But her study of regrowth in Alaska’s burned areas, published Thursday in the journal Science, turned out to be unexpectedly hopeful. The scorched boreal forests are rapidly regenerating. In fact, they are on track to hold a lot more carbon than they did before the fires.
How is that possible? Before the fires, slow-growing black spruce trees had dominated the boreal forest. In the severely burned areas, however, faster-growing aspen and birch trees have largely replaced them. These deciduous trees suck carbon out of the air and transform it into wood much more quickly than the previous evergreen forest.
“For me, it was surprising,” Mack said. “I didn’t think all that carbon could be offset. We keep talking about this runaway train of positive feedbacks accelerating climate change, but this looks like a brake.”
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