Fixing Agricultural Carbon Offsets Can’t Drive Substantial Climate Mitigation

Last month, the US Senate passed the Growing Climate Solutions Act, a bipartisan but misguided effort to mitigate climate change. The bill would make it easier for farmers, ranchers, and other rural landowners to generate carbon credits by reducing their carbon footprint and to subsequently sell the credits to companies interested in offsetting their emissions. Members of the House of Representatives, now considering the bill, should acknowledge carbon credits alone cannot substantially reduce emissions and prioritize policies and investments that drive real, verifiable, and scalable reductions in agriculture and land-use emissions.

Over the past several years, a variety of companies and nonprofits have launched efforts to generate carbon credits from agriculture. These companies pay farmers, ranchers, and other land managers to reduce their greenhouse gas emissions from fertilizer, manure, and other sources and to use farming practices that store or sequester carbon in their soil. This new agricultural carbon market has attracted interest from major companies like Microsoft, Shopify, and Corteva Agriscience.

The Growing Climate Solutions Act would create a Department of Agriculture program to 'reduce the barriers to entry' in the agricultural carbon market. Specifically, it would certify a) organizations assisting farmers to participate in carbon markets and b) organizations verifying whether farmers have complied with the rules for generating and selling carbon credits.

While the bill could help address some critical problems plaguing the agricultural carbon market, it also legitimizes agricultural carbon markets, portraying them as an important solution to climate change. Unfortunately, agricultural carbon markets inherently cannot provide substantial climate mitigation due to several problems that we previously described last year in our piece, The Limits of Soil Carbon Sequestration.

These limits include:

• Additionality: It is impossible to verify that the activities companies are paying for would not have occurred in the absence of the carbon market. For instance, if a farmer would financially benefit by planting cover crops — crops planted during that off-season that can sequester carbon and sometimes reduce fertilizer use — then paying them for carbon credits doesn’t lead to any additional climate mitigation.
• Permanence: Carbon that is sequestered in soil can be released when farmers change their practices, land changes hands, or even when temperatures warm.
• Leakage: Some farming practices can reduce crop yields, thereby leading to the expansion of farmland elsewhere.
• Limited potential: There is not enough potential supply of emissions reductions and sequestration in the agricultural sector to offset a large portion of emissions in other industries. If companies were willing to pay $50 per ton of carbon credit — several times higher than current prices — US agriculture could reduce and sequester no more than 368 million metric tons of carbon dioxide-equivalent (CO2e) per year, less than 7% of current US net emissions.^{This is likely an overestimate as it does not account for transaction costs such as the cost to measure, monitor, report and verify emissions reductions or sequestration, or fees charged by carbon brokers.}Even if all carbon markets could eliminate agricultural emissions and enable farmers to plant cover crops everywhere possible, this would offset less than 13% of emissions.^{Using the maximum estimate for climate mitigation from cover crops from Fargione et al. (2018).}

There are many alternative approaches for companies and the government to mitigate climate change. As Project Drawdown Executive Director Jon Foley proposed recently, companies could do all of the following:

• Reduce their own emissions as quickly and as much as possible;
• Only buy carbon credits that remove and sequester carbon, such as through cover crops, to offset truly unavoidable emissions — like those from long-haul aviation — and to offset historic emissions; and
• Donate to causes that advance climate mitigation and adaptation, such as helping low-income and vulnerable communities, reduce emissions and become more climate-resilient.

It’s important to note that Congress has a slew of other climate proposals it should consider. Over 60 bills related to climate change have been introduced in the Senate, including several that would help decarbonize agriculture such as the Climate Stewardship Act.

Rather than suggesting farming is “the solution” to climate change by banking on carbon offsets, companies and policymakers must prioritize the larger-scale and verifiable changes necessary to address climate change.