American Carbon Registry

The American Carbon Registry (ACR) is a voluntary carbon offset program operated as a nonprofit enterprise of Winrock International, a development NGO headquartered in Arkansas. Established in 1996, ACR describes itself as the first private voluntary greenhouse gas registry in the world, predating the Kyoto Protocol's Clean Development Mechanism and most peer standards such as Verra's Verified Carbon Standard, the Gold Standard, and Climate Action Reserve.

ACR develops methodologies, approves third-party validation and verification bodies, and issues serialized Emission Reduction Tons (ERTs)—each representing one metric ton of CO₂-equivalent reduced, avoided, or removed. Project categories include improved forest management, reforestation, avoided forest conversion, agricultural soil carbon, livestock methane, landfill gas, industrial gases, and engineered removals such as direct air capture and carbon capture and storage.

Beyond the voluntary market, ACR is an approved Offset Project Registry (OPR) under the California Air Resources Board (CARB) cap-and-trade program, alongside Climate Action Reserve and Verra. In that compliance capacity it issues credits eligible for use by regulated California (and linked Québec) entities, primarily for U.S. Forest Projects, Ozone Depleting Substances, Livestock, Mine Methane Capture, and Rice Cultivation protocols.

ACR has been a frequent subject of debate over offset integrity. Investigations by outlets including ProPublica, The Guardian, and MIT Technology Review, as well as academic studies, have questioned baseline assumptions and additionality in some improved forest management projects registered with ACR. The registry has responded by tightening protocols and participating in efforts such as the Integrity Council for the Voluntary Carbon Market (ICVCM), which assesses programs against its Core Carbon Principles.

For MUN delegates and researchers, ACR is relevant when analyzing voluntary carbon markets, Article 6 of the Paris Agreement, corporate net-zero claims, and U.S. subnational climate policy.