As climate change causes warmer winters, an invasive insect known as the hemlock woolly adelgid has spread into forests across the eastern United States, killing hemlock trees from Maine to Alabama.
Scientists fear the insect's spread could also accelerate climate change.
Hemlocks, like other trees, absorb carbon from the atmosphere that contributes to global warming as they grow.
Danielle Ignace of the University of British Columbia explains that when hemlock needles fall, the carbon they contain is stored in the soil for long periods of time.
Ignace: “These needles are very difficult to break down. … They don't break down easily, but they do build this strong, deep, and really intact organic layer of soil. So it has tremendous carbon storage potential.”
But when the hairy adelgid kills a hemlock, that evergreen tree is usually replaced by deciduous trees like black birch. Black birch leaves decompose much faster than hemlock needles.
Ignace: “Those leaves decompose more easily.”
…It releases carbon back into the atmosphere faster.
So as furry adelgid spreads, less carbon is stored underground in eastern forests—which could make global warming worse.
Reporting credit: Ethan Friedman/ChavoBart Digital Media
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