Plant a Trillion Trees, But Don’t Stop There
(Bloomberg Opinion) -- It’s easy to criticize just about any proposed climate change solution as not effective enough. The buildup of greenhouse gases is simply too big of a problem to be solved by one course of action alone, whether it’s increasing the use of solar energy or giving up beef or capturing carbon from the atmosphere. A recent estimate that planting lots of trees could soak up most of our excess carbon is, unfortunately, a little too good to be true.
The claim comes out of a paper published last week in the journal Science. Researchers from the Swiss Federal Institutes of Technology in Zurich estimated how many more trees our planet could hold, and how much carbon those would absorb. They reached the conclusion that new trees could soak up a whopping two-thirds of the excess carbon humanity has added to the atmosphere since the industrial revolution. (Others have chimed in to say the theoretical potential is just one-third, and that the practical potential is much less because some of the proposed land is currently grazing pastures or natural savannas with their own unique ecosystems.)
A story in the Guardian newspaper called this “mind-blowing potential” to combat global warming and quoted the paper’s lead author, Thomas Crowther, saying that “forest restoration isn’t just one of our climate change solutions, it is overwhelmingly the top one.”
The risk in embracing such a theory is that it might mislead people into thinking we don’t need to cut emissions or continue research into other solutions. Multiple approaches are required, even if mass reforestation were practical and imminent – which it isn’t.
Robin Chazdon of the University of Connecticut, who co-authored an accompanying commentary in Science, pointed to several ongoing reforestation efforts – the biggest of which is the 2011 Bonn Challenge, with the goal of planting 170 million hectares by 2030. Her concern is that mass planting of non-native trees could disrupt local ecology in some places. Everyone can get behind planting trees that will have a positive impact all around, but that won’t add up to the Crowther team’s target of a trillion. The researchers estimated that the planet currently supports about 3 trillion trees, half of the total before humanity started to destroy them.
You can see why it’s dangerous to get caught up in the “one big idea” model; the idea is always vulnerable to being shot down. With climate change, like many serious problems, doing nothing is not a viable option. In the absence of a single solution, we need to deploy many partial ones – including lots and lots of tree planting.
To contact the editor responsible for this story: Philip Gray at philipgray@bloomberg.net
This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.
Faye Flam is a Bloomberg Opinion columnist. She has written for the Economist, the New York Times, the Washington Post, Psychology Today, Science and other publications. She has a degree in geophysics from the California Institute of Technology.
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