上文介绍了NCC文章关于全球尺度上IAM模拟和国家清单数据的差异，以及其中的影响因素。

这个问题的解决至关重要。AFOLU作为减缓措施很有潜力的一方面，2023全球盘点时预计会得到各方的关注。IPCC方法学很好支持了各国的排放核算。IPCC方法学的实践表明，目前的技术方法虽然仍存在一些问题，但重在其可行性。短期内再次更新IPCC方法学是不可能的，重点可能是督促各国改善核算精度、透明度等方面的问题，或者对清单提出更加详细的要求。

目前，IAMs或者bookkeeping模式计算得到全球AFOLU是净的二氧化碳的碳源，而清单数据显示则是碳汇。这种差异在区域或者国家尺度上也是存在的。 极大的影响未来全球和各国减缓路径的落实。

NCC文章指出，在全球尺度上两者的差异在于，一些国家清单数据在统计时未排除人类管理土地上的人为土地利用的间接影响及一些自然影响（包括环境变化而导致的碳通量变化，比如CO2肥效、人为排放导致的温湿变化这些），而这些影响在IAM模式里面被列入了non-anthropogenic。

NCC的方法，通过将差异项在IAM全球模式里面进行重新分配，最终在全球尺度上弥合了IAM模拟和清单数据的差异。

但是，也发现国家尺度上数据差距的影响因素可能更多。” This pattern is also largely confirmed at the level of large countries (Supplementary Section 6), with almost full reconciliation of the estimates in European Union (EU), Russia, United States, Brazil and Indonesia, but not fully in Canada and China. This indicates that the gap between IAMs and NGHGIs is mostly a matter of the different areas considered and a different allocation of fluxes (Extended Data Fig. 1 and Supplementary Section 7). Our scenario-specific results can be directly used by other studies at the global and regional levels (Supplementary Section 8), but additional analyses would be required for specific countries.”

Supplementary Section 6

 The adjustment of the original IMAGE CO2 flux allows an almost full reconciliation with NGHGIs in the EU, Russia, USA, Brazil and Indonesia, but not fully in Canada and in China. For Canada, possible explanations of the mismatch are: (i) recent indirect effects on the forest sink are mostly not captured by the NGHGI6, and (ii) the NGHGI includes the impact of natural disturbances (insect and wildfires), equal to about 0.1 GtCO2/y in the period 2005-2015, which are mostly not captured by IMAGE. For China, the large difference is due to the fact that IMAGE estimates a large source from land-use change which is not reported by the NGHGI, while the NGHGI estimates a large sink from forest which is not captured by IMAGE. These differences would require further investigation.

Supplementary Figure 7. Global anthropogenic land CO2 emissions (LUC, mainly from deforestation), removals (Forest management) and net flux (Total, without harvested wood products), as originally estimated in IMAGE (red bars), adjusted to the NGHGIs approach (dashed red bars) and from NGHGIs for selected countries in the period 2005-2015.

中国的问题可能还需要中国专家自己来解决，这既是科学问题，也是国家发展政策制定的需求。

目前，国内常常强调海洋和陆地生态碳汇对于减排有很大的作用，但有多少是真正人类活动（管理）贡献的？？？  这才是亟需算清楚的一笔账。碳中和需要的是人类排放自己解决掉，纯粹自然的碳源汇是排除在外的。