Reducing emissions from deforestation and forest degradation (REDD+) has gained international attention over the past decade, as manifested in both United Nations policy discussions and hundreds of voluntary projects launched to earn carbon-offset credits. There are ongoing discussions about whether and how projects should be integrated into national climate change mitigation efforts under the Paris Agreement. One consideration is whether these projects have generated additional impacts over and above national policies and other measures. To help inform these discussions, we compare the crediting baselines established ex-ante by voluntary REDD+ projects in the Brazilian Amazon to counterfactuals constructed ex-post based on the quasi-experimental synthetic control method. We find that the crediting baselines assume consistently higher deforestation than counterfactual forest loss in synthetic control sites. This gap is partially due to decreased deforestation in the Brazilian Amazon during the early implementation phase of the REDD+ projects considered here. This suggests that forest carbon finance must strike a balance between controlling conservation investment risk and ensuring the environmental integrity of carbon emission offsets. Relatedly, our results point to the need to better align project- and national-level carbon accounting.

过去十年来，减少毁林和森林退化（REDD +）引起的排放已引起国际关注，这在联合国政策讨论和为赚取碳抵消信用而发起的数百个自愿项目中均得到体现。目前正在就是否以及如何将项目纳入《巴黎协定》之下的国家减缓气候变化努力进行讨论。一个考虑因素是这些项目是否在国家政策和其他措施之上产生了额外的影响。为了帮助为这些讨论提供信息，我们将巴西亚马逊地区的自愿REDD +项目事前建立的信用基准与基于准实验综合控制方法事后构建的反事实进行了比较。我们发现，计入信用额度的基线假设的森林砍伐率始终高于综合控制点的反事实森林损失。这种差距部分是由于在此考虑的REDD +项目的早期实施阶段，巴西亚马逊地区的森林砍伐减少。这表明森林碳融资必须在控制保护投资风险和确保碳排放补偿的环境完整性之间取得平衡。相关地，我们的结果表明需要更好地协调项目和国家一级的碳核算。这表明森林碳融资必须在控制保护投资风险和确保碳排放补偿的环境完整性之间取得平衡。相关地，我们的结果表明需要更好地协调项目和国家一级的碳核算。这表明森林碳融资必须在控制保护投资风险和确保碳排放补偿的环境完整性之间取得平衡。相关地，我们的结果表明需要更好地协调项目和国家一级的碳核算。