What Is Additionality in a Carbon Market?

The short answer: “Additionality” is a huge component of verifying whether a carbon market is creating quality credits. It’s asking, “Is this project sequestering carbon or decreasing emissions in a way that would not happen otherwise?”

An additional project is one that would not have been completed if it were “business as usual,” a definition used in many verification projects to assess the validity of credits.

• It’s the grand “what if” plaguing market development. It’s asking a question about the alternate reality in which a program or market does not exist.
• Additionality is one of a suite of concepts that verifiers are using to determine the quality and validity of a carbon credit. If a credit is additional, it’s more credible to buyers seeking to voluntarily offset their emissions.

Break it down: for example, imagine a land owner willing to plant trees on their land, sequestering carbon in roots and biomass. But would the trees have been planted whether or not the land manager was not participating in the program?

• If the answer is yes—if the land manager was going to plant the trees either way—then the practice isn’t additional.
• But if the answer is no—if the program is the primary reason that the land manager plants the trees, and they would not do so without it—then the practice meets the test. It is truly additional.

Why does it matter?

For carbon programs to succeed in offsetting unavoidable emissions (think transportation, energy production, or manufacturing), the amount of carbon sequestered needs to actually have been sequestered, and it needs to be an added amount compared to what would have been sequestered without a program or market to pay for the practice.

Without meeting the “additionality” benchmark, some critiques of voluntary carbon markets point out that companies may be tempted to purchase credits instead of reducing their own emissions. Others even go so far as to call it greenwashing.

• But there have been debates about the importance of additionality in agricultural carbon markets. This benchmark leaves those who have already started implementing practices that sequester carbon out of carbon markets.
• Even though “additional” practices do not include farmers who have already made changes that sequester carbon, it’s important to remember that improving soil health can be “profitable even without soil carbon payments,” the Soil Health Institute writes in Crops & Soils. The benefits of adopting practices that sequester soil carbon extend far beyond soil carbon payments.
• Transparency is also an important part of creating credible, quality carbon credits. As the Carbon Offset Guide explains, discerning buyers are probably going to want to review the methods used to generate a credit and verify additionality.

The big picture: additionality is one of those key terms that will pop up again and again as markets develop. Understanding exactly how payments are impacting landowners’ and land managers’ decisions to change practices can help determine the quality and validity of the carbon credits they generate.

Photo by NRCS/SWCS and Lynn Betts.