Flaws in carbon credit programs for farms draw concerns

As fears about climate change grow, a new “gold rush” of carbon credit programs are incentivizing US farmers to slash greenhouse gas emissions generated by the practices they use growing crops and raising livestock. But experts say the programs face difficulty in ensuring that the credits provided truly match emission cuts.

The US Environmental Protection Agency (EPA) estimates that agriculture accounted for 11.2% of US greenhouse gas emissions in 2020. Greenhouse gases trap heat from the sun in the atmosphere, triggering harmful climate changes and increasing temperatures worldwide. Carbon dioxide is released when farmers till their fields, for instance, and nitrous oxide, a greenhouse gas with almost 300 times more warming potential than carbon dioxide, is released when farmers spread fertilizer or manure on their fields.

In one increasingly popular mitigation strategy, private carbon programs pay farmers for implementing practices known to reduce greenhouse gas emissions, generating credits that can then be sold to large corporations wanting to use the credits to offset their own emissions. One tradable carbon credit equals one ton of carbon dioxide, or the equivalent amount of a different greenhouse gas reduced, sequestered or avoided.

Many programs pay farmers for planting cover crops — a practice shown to limit the amount of carbon dioxide that soils release into the air. But few offer any incentives for farmers to reduce nitrous oxide emissions, though nitrous oxide is a highly potent greenhouse gas. A 2021 report estimated nitrous oxide made up for 2.4% of total global greenhouse gas emissions, while the EPA estimates nitrous oxide makes up over half of all greenhouse gas emissions from agriculture.

As the popularity of carbon credit programs grows, concerns and questions about the validity of the programs to truly reduce greenhouse gas emissions from farms are also emerging. Carbon credit schemes have been criticized for a lack of rigorous accounting of the amount of carbon dioxide lost from soils. Additionally, the difficulty of measuring nitrous oxide emissions could mean some businesses are paying for carbon credits that don’t really reduce emissions as much as promised.

That’s the “worst-case scenario,” said Eric Slessarev, a biogeochemist at the Lawrence Livermore National Laboratory. “We better hope we’re right, on average, because if we’re not right, then we’re in trouble,” he said.