The application of different approaches calculating the anthropogenic carbon net flux from land, leads to estimates that vary considerably. One reason for these variations is the extent to which approaches consider forest land to be “managed” by humans, and thus contributing to the net anthropogenic flux. Global Earth Observation (EO) datasets characterising spatio-temporal changes in land cover and carbon stocks provide an independent and consistent approach to estimate forest carbon fluxes. These can be compared against results reported in National Greenhouse Gas Inventories (NGHGIs) to support accurate and timely measuring, reporting and verification (MRV). Using Brazil as a primary case study, with additional analysis in Indonesia and Malaysia, we compare a Global EO-based dataset of forest carbon fluxes to results reported in NGHGIs. Between 2001 and 2020, the EO-derived estimates of all forest-related emissions and removals indicate that Brazil was a net sink of carbon (− 0.2 GtCO2yr−1), while Brazil’s NGHGI reported a net carbon source (+ 0.8 GtCO2yr−1). After adjusting the EO estimate to use the Brazilian NGHGI definition of managed forest and other assumptions used in the inventory’s methodology, the EO net flux became a source of + 0.6 GtCO2yr−1, comparable to the NGHGI. Remaining discrepancies are due largely to differing carbon removal factors and forest types applied in the two datasets. In Indonesia, the EO and NGHGI net flux estimates were similar (+ 0.6 GtCO2 yr−1), but in Malaysia, they differed in both magnitude and sign (NGHGI: -0.2 GtCO2 yr−1; Global EO: + 0.2 GtCO2 yr−1). Spatially explicit datasets on forest types were not publicly available for analysis from either NGHGI, limiting the possibility of detailed adjustments. By adjusting the EO dataset to improve comparability with carbon fluxes estimated for managed forests in the Brazilian NGHGI, initially diverging estimates were largely reconciled and remaining differences can be explained. Despite limited spatial data available for Indonesia and Malaysia, our comparison indicated specific aspects where differing approaches may explain divergence, including uncertainties and inaccuracies. Our study highlights the importance of enhanced transparency, as set out by the Paris Agreement, to enable alignment between different approaches for independent measuring and verification.

中文翻译：

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注意差距：协调地球观测和国家报告的热带森林碳通量估算需要透明度

应用不同的方法计算来自陆地的人为碳净通量，导致估计结果存在很大差异。造成这些差异的原因之一是各种方法认为林地是由人类“管理”的程度，从而对净人为通量做出了贡献。全球地球观测（EO）数据集描述了土地覆盖和碳储量的时空变化，为估计森林碳通量提供了独立且一致的方法。这些可以与国家温室气体清单 (NGHGI) 中报告的结果进行比较，以支持准确及时的测量、报告和验证 (MRV)。我们以巴西为主要案例研究，并在印度尼西亚和马来西亚进行了额外分析，将基于全球 EO 的森林碳通量数据集与 NGHGI 中报告的结果进行了比较。2001年至2020年间，EO得出的所有与森林相关的排放和清除的估计表明，巴西是净碳汇（− 0.2 GtCO2yr−1），而巴西的NGHGI报告了净碳源（+ 0.8 GtCO2yr−1） 。在使用巴西 NGHGI 对管理森林的定义和清单方法中使用的其他假设调整 EO 估算后，EO 净通量成为 + 0.6 GtCO2yr−1 的来源，与 NGHGI 相当。其余差异主要是由于两个数据集中应用的碳去除因子和森林类型不同所致。在印度尼西亚，EO 和 NGHGI 净通量估计值相似（+ 0.6 GtCO2 yr−1），但在马来西亚，它们的大小和符号均不同（NGHGI：-0.2 GtCO2 yr−1；全球 EO：+ 0.2 GtCO2 yr−1） 1）。森林类型的空间明确数据集无法公开用于 NGHGI 的分析，限制了详细调整的可能性。通过调整 EO 数据集以提高与巴西 NGHGI 管理森林估计的碳通量的可比性，最初的不同估计在很大程度上得到了协调，并且可以解释剩余的差异。尽管印度尼西亚和马来西亚可用的空间数据有限，但我们的比较表明了不同方法可能解释差异的具体方面，包括不确定性和不准确性。我们的研究强调了《巴黎协定》规定的增强透明度的重要性，以实现独立测量和验证的不同方法之间的协调。