School of Geography & Sustainable Development, University of St Andrews, St Andrews, UK.
School of Ocean Sciences, Bangor University, Menai Bridge, UK.
Glob Chang Biol. 2024 Nov;30(11):e17559. doi: 10.1111/gcb.17559.
Blue carbon ecosystems (BCEs) remove carbon dioxide from the atmosphere and store significant amounts of organic carbon (OC) in their soils. Consequently, the protection and restoration of BCEs may contribute to net greenhouse gas emissions abatement and help address the global challenges of both mitigating and adapting to climate change. An ongoing debate is whether OC sequestered out with the blue carbon (BC) project and transported to its present location (allochthonous) should be counted as 'additional'. There are inconsistencies in the treatment of allochthonous carbon between BCE methodologies, potentially undermining the credibility of global BC accounting initiatives. To explore these inconsistences, we compare the methodologies which we were able to find online, with particular focus on the VERRA, IPCC and BlueCAM methodologies, and review the science underlying any approach to account for allochthonous OC. Our findings indicate that there are currently no robust scientific approaches to define an appropriate apportioning of allochthonous OC for discounting in the calculation of additionality. We therefore advocate for the inclusion of allochthonous OC in BC crediting projects when an observational and experimental approach does not support the calculation (and discounting) of the refractory allochthonous carbon contribution.
蓝碳生态系统（BCEs）从大气中吸收二氧化碳，并在其土壤中储存大量有机碳（OC）。因此，保护和恢复 BCEs 可能有助于减少温室气体净排放，并有助于应对缓解和适应气候变化的全球挑战。目前正在争论的一个问题是，是否应将随蓝碳（BC）项目一起封存并运至当前位置的 OC（异源）视为“额外的”。在 BCE 方法学中，异源碳的处理方式不一致，这可能会破坏全球 BC 核算计划的可信度。为了探讨这些不一致之处，我们比较了我们在网上找到的方法，特别关注 VERRA、IPCC 和 BlueCAM 方法，并审查了为核算异源 OC 而采用的任何方法背后的科学依据。我们的研究结果表明，目前尚无可靠的科学方法来定义适当的异源 OC 分配，以在额外性计算中进行折扣。因此，我们主张在观测和实验方法不支持计算（和折扣）难降解异源碳的情况下，将异源 OC 纳入 BC 入计费项目。
