Tropical forest carbon offsets deliver partial gains amid persistent over-crediting.

REDD+ (Reducing Emissions from Deforestation and Degradation Plus) projects generate carbon credits to offset emissions, but recent studies have questioned their effectiveness. We evaluated 52 voluntary REDD+ projects across 12 tropical countries using synthetic control methods. Only a minority of project units showed statistically significant reductions in deforestation, and just 19% met their reported emissions targets. Nonetheless, many underperforming projects still delivered partial climate benefits, with an estimated 13.2% of tradable credits supported by counterfactual analysis. Effectiveness varied by region, with stronger performance in Brazil and Africa. Although systematic over-crediting remains a concern, our results suggest greater climate benefits than previous assessments. Improving baseline methodologies and strengthening verification frameworks will be essential for enhancing the credibility and impact of forest carbon offsets. Editor's summary: Forest degradation is a major contributor to greenhouse gas emissions, such that forest protection projects are used as carbon offsets for greenhouse gas–producing activities in voluntary carbon markets. Recently, the effectiveness of carbon-offsetting programs such as REDD+ (Reducing Emissions from Deforestation and Degradation Plus) has been called into question, causing a decline in carbon offset values. Tang et al. addressed this question with updated analyses incorporating many projects and carefully chosen controls. Across 52 REDD+ Avoided Unplanned Deforestation projects from 12 countries in South America, Africa, and Southeast Asia, the authors found greater climate benefits than previous studies but low efficacy overall: Less than 20% of projects met their emissions targets. Project success and overestimation both varied considerably between countries. —Bianca Lopez [ABSTRACT FROM AUTHOR]