Don’t count on trees to stop global warming, scientists say

By Chelsea Harvey | 11/19/2024 06:10 AM EST

Forests absorb planet-warming pollution, but world leaders shouldn’t include them in plans to reach net-zero emissions, one study recommends.

Old-growth Douglas fir trees loom over the Salmon River Trail in the Mount Hood National Forest outside Zigzag, Oregon.

Old-growth Douglas fir trees loom over the Salmon River Trail in the Mount Hood National Forest outside Zigzag, Oregon. Rick Bowmer/AP

Countries around the world have turned to natural carbon sinks such as forests and wetlands to help them achieve their climate targets. The thinking is that these landscapes naturally soak up carbon dioxide from the atmosphere and so can cancel out ongoing emissions from fossil fuels.

But that kind of approach is a mistake, say some of the world’s leading scientists in a new study. And it could jeopardize the Paris Agreement’s vulnerable climate goals.

Because carbon dioxide lingers in the atmosphere for decades, forests and other natural carbon sinks are still absorbing emissions released by humans years ago. And that carbon doesn’t stay in the ground forever, either. It becomes part of the Earth’s natural carbon cycle, eventually escaping back into the atmosphere when the trees die before eventually being reabsorbed again by some other natural landscape.

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It’s all part of a giant natural equilibrium. But the system only stays in balance as long as emissions from human sources wind down to zero. If humans depend on natural carbon sinks to balance out ongoing future emissions, the world will just keep on warming.

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