We take time out from the conformism of “the science is settled” (because 97 percent!) to remind everyone to do their good deed and plant a tree for the planet. Except—what’s this? Planting trees might not be good for the planet? That’s the argument that appeared yesterday in the New York Times from Yale chemist Nadine Unger. Yup: the article is “To Save the Planet, Don’t Plant Trees.”
Start oiling up your chainsaw, because:
Deforestation accounts for about 20 percent of global emissions of carbon dioxide. The assumption is that planting trees and avoiding further deforestation provides a convenient carbon capture and storage facility on the land.
That is the conventional wisdom. But the conventional wisdom is wrong.
In reality, the cycling of carbon, energy and water between the land and the atmosphere is much more complex. Considering all the interactions, large-scale increases in forest cover can actually make global warming worse.
Complex, you say? Maybe we don’t understand the phenomenon fully? But 97 percent!
Anyway, to continue:
In order to grow food, humans have changed about 50 percent of the earth’s surface area from native forests and grasslands to crops, pasture and wood harvest. Unfortunately, there is no scientific consensus on whether this land use has caused overall global warming or cooling. Since we don’t know that, we can’t reliably predict whether large-scale forestation would help to control the earth’s rising temperatures. . . (Emphasis added.)
The science says that spending precious dollars for climate change mitigation on forestry is high-risk: We don’t know that it would cool the planet, and we have good reason to fear it might have precisely the opposite effect. More funding for forestry might seem like a tempting easy win for the world leaders at the United Nations, but it’s a bad bet.
I say we better chop down a lot of trees just to be safe. Precautionary principle and all that.