An integrity assessment of global forest carbon offset projects

Forest carbon offset projects are vital for carbon removal; however, concerns over their integrity persist due to allegations of over-crediting by major carbon-crediting programs. This study evaluates the integrity of afforestation and reforestation (AR) and improved forest management (IFM) projects across six prominent carbon-crediting programs: the Clean Development Mechanism (CDM), Verified Carbon Standard (VCS), Gold Standard (GS), American Carbon Registry (ACR), Climate Action Reserve (CAR), and Chinese Certificated Emissions Reduction (CCER). We compare emissions reductions estimated using remote sensing data with those verified by third-party verifiers. Although 665 projects were initially identified, over 70% lacked sufficient data for evaluation, leaving 154 projects under the CDM, VCS, ACR, and CAR programs across 24 countries for our analysis. Our findings reveal a significant risk of over-crediting, with third-party verified credits averaging 121% higher than satellite-based estimates of emission reductions. Notably, IFM projects under the CAR program exhibited the least bias. We also observed that large-scale methodologies, verifiers with focused expertise, projects in more developed host countries, and favourable business environments were correlated with lower overestimation. Our study emphasizes the need for improved tracking and verification processes to enhance the credibility of forest carbon offset credits and foster greater confidence in natural-based carbon removal solutions.