Don’t Bank on Biden’s Carbon Bank

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President Joe Biden’s fight against climate change is headed down to the farm, and with good reason. In 2018, agriculture accounted for fully 10% of total U.S. greenhouse-gas emissions. One proposal for reducing that figure has recently intrigued both Biden’s team and influential congressional Democrats: Why not pay farmers to preserve carbon in their fields?

The idea would be to establish a federal “carbon bank” that would commit to buying credits from farmers who employ sustainable agricultural methods, such as planting off-season cover crops or switching to no-till farming to prevent soil erosion. The more carbon a farmer sequestered underground, the more credits he could sell. Last week, soon-to-be Secretary of Agriculture Tom Vilsack signaled his support for the concept.

As attractive as this idea may sound, it’s almost certainly a mistake.

Over the past 12,000 years, agriculture has accounted for the release of about 8% of the carbon stored in the world’s soils. Traditionally, clearing land and tilling soil played the biggest role in these emissions. But in recent years, meat production and yield-boosting technology have become even bigger threats. In the U.S., the two leading sources of agricultural carbon are nitrous oxide from fertilizer application and methane emissions (aka burps) from livestock. Management (and mismanagement) of manure has also contributed.

In theory, though, farms could be climate-positive. Plants absorb carbon from the air during photosynthesis and use it to create nutrients. Eventually that carbon is returned to the soil, and the volumes sequestered in this process are potentially massive. As of 2019, U.S. forests had banked a total of 58.7 billion tons of carbon, nearly 10 times the volume emitted by Americans in a given year. Farms should be able to do the same. One recent report argued that soil-sequestration techniques already in use could remove carbon equal to about 5% of 2018 U.S. greenhouse emissions.

Such estimates have caught the attention of companies eager to offset their own emissions by buying up carbon credits from farmers. Over the past year, private markets have proliferated to facilitate such exchanges. Bayer AG recently announced that it was helping 1,200 farmers in Brazil and the U.S. adopt regenerative farming methods and planned to purchase credits from them to fulfill its corporate climate pledges.

As laudable as these initiatives are, they rest on some shaky ground. First, the for-profit companies that set the terms of these markets might be viewed as self-serving, and their credits, well, less than credible. Second, the science of sequestration is hardly settled. Different soils in different places absorb, retain and emit carbon at very different rates. Even in what appear to be uniform fields, carbon content can vary fivefold.

Making matters worse, scientists now know that some sustainable practices — such as planting cover crops — don’t work as well in some regions as in others. Even the techniques used to measure soil carbon are proving to be highly contentious. Such uncertainties undermine the value of a tradeable credit market — and increase the risk that carbon banks, government or private, will end up benefiting farmers and other private interests far more than the climate.

That’s not to say that the government shouldn’t play a role in mitigating farm-based emissions. For one thing, the Department of Energy’s Advanced Research Projects Agency-Energy (or ARPA-E) is already funding research on measuring soil carbon. The Biden administration should make expanding such projects a priority.

It should also reform existing farm programs with climate issues in mind. Step one should be overhauling the massive federal crop-insurance program to reward farmers who incorporate sustainable practices. That could not only reduce emissions (the program insures more than  300 million acres), but also help mitigate soil erosion and other negative effects of irresponsible farming and climate change. Likewise, expanding the popular Conservation Reserve Program, which pays farmers to idle land and convert it to cover that reduces erosion (and sequesters carbon), could ensure that millions of additional acres are set aside for sustainable purposes.

Eventually, there may be enough data to make soil carbon credits a credible reality. Until then, farmers and sustainably minded companies need climate solutions they can actually bank on.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Adam Minter is a Bloomberg Opinion columnist. He is the author of “Junkyard Planet: Travels in the Billion-Dollar Trash Trade” and "Secondhand: Travels in the New Global Garage Sale."

©2021 Bloomberg L.P.

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