Overstated carbon emission reductions from voluntary REDD+ projects in the Brazilian Amazon
Overstated carbon emission reductions from voluntary REDD+ projects in the Brazilian Amazon
复制标题
巴西亚马逊地区自愿 REDD 项目的碳减排量被夸大
DOI：
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发表时间：
2020
影响因子：
11.1
通讯作者：
A. Kontoleon
中科院分区：
文献类型：
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作者：
Thales A. P. West;J. Börner;E. Sills;A. Kontoleon
目前正在努力将自愿REDD+项目声称的避免毁林所减少的碳排放纳入国家温室气体排放清单。这需要仔细考虑减少的碳排放是否以及有多少可以归因于项目。但是，关于这种自愿活动的效力的可信证据是有限的。本文采用准实验综合控制方法对巴西亚马逊地区12个自愿性REDD+项目的因果效应进行了研究。我们将这些事后估计的影响与那些基于事前基线的项目所声称的森林损失减少量进行了比较。结果表明，公认的量化碳信用额的方法夸大了对避免砍伐森林和减缓气候变化的影响。减少毁林和森林退化造成的排放（REDD+）在过去十年中引起了国际关注，这体现在联合国的政策讨论和为获得碳抵消信用额度而启动的数百个自愿项目中。目前正在讨论是否以及如何根据《巴黎协定》将项目纳入各国减缓气候变化的努力。一个考虑因素是，这些项目是否产生了超出国家政策和其他措施的额外影响。为了帮助这些讨论，我们比较了巴西亚马逊地区自愿REDD+项目事先建立的信用基线与基于准实验综合控制方法事后构建的反事实。我们发现，在综合控制地点，信用基线假设的森林砍伐率始终高于反事实的森林损失。造成这一差距的部分原因是，在本文所考虑的REDD+项目的早期实施阶段，巴西亚马逊地区的森林砍伐有所减少。这表明森林碳金融必须在控制保护投资风险和确保碳排放抵消的环境完整性之间取得平衡。与此相关，我们的研究结果表明，需要更好地协调项目和国家层面的碳核算。
Significance There are efforts to integrate the reduced carbon emissions from avoided deforestation claimed by voluntary REDD+ projects into national greenhouse gas emission inventories. This requires careful consideration of whether and how much of the reduced carbon emissions can be attributed to projects. However, credible evidence on the effectiveness of such voluntary activities is limited. We adopted the quasi-experimental synthetic control method to examine the causal effects of 12 voluntary REDD+ projects in the Brazilian Amazon. We compared these ex-post estimates of impacts with the reductions in forest loss claimed by those projects based on ex-ante baselines. Results suggest that the accepted methodologies for quantifying carbon credits overstate impacts on avoided deforestation and climate change mitigation. 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.