Abstract. In support of the Global Stocktake of the Paris Agreement on Climate change, this study presents a comprehensive framework to process the results of atmospheric inversions in order to make them suitable for evaluating UNFCCC national inventories of land-use carbon dioxide (CO₂) emissions and removals, corresponding to the Land Use, Land Use Change and Forestry and waste sectors. We also deduced anthropogenic methane (CH₄) emissions regrouped into fossil and agriculture and waste emissions, and anthropogenic nitrous oxide (N₂O) emissions from inversions. To compare inversions with national reports, we compiled a new global harmonized database of national emissions and removals from periodical UNFCCC inventories by Annex I countries, and from sporadic and less detailed emissions reports by Non-Annex I countries, given by National Communications and Biennial Update Reports. The method to reconcile inversions with inventories is applied to selected large countries covering 78 % of the global land carbon uptake for CO₂, as well as emissions and removals in the land use, land use change and forestry sector, and top-emitters of CH₄ and N₂O. Our method uses results from an ensemble of global inversions produced by the Global Carbon Project for the three greenhouse gases, with ancillary data. We examine the role of CO₂ fluxes caused by lateral transfer processes from rivers and from trade in crop and wood products, and the role of carbon uptake in unmanaged lands, both not accounted for by the rules of inventories. Here we show that, despite a large spread across the inversions, the median of available inversion models points to a larger terrestrial carbon sink than inventories over temperate countries or groups of countries of the Northern Hemisphere like Russia, Canada and the European Union. For CH₄, we find good consistency between the inversions assimilating only data from the global in-situ network and those using satellite CH₄ retrievals, and a tendency for inversions to diagnose higher CH₄ emissions estimates than reported by inventories. In particular, oil and gas extracting countries in Central Asia and the Persian Gulf region tend to systematically report lower emissions compared to those estimated by inversions. For N₂O, inversions tend to produce higher anthropogenic emissions than inventories for tropical countries, even when attempting to consider only managed land emissions. In the inventories of many non-Annex I countries, this can be tentatively attributed to either a lack of reporting indirect N₂O emissions from atmospheric deposition and from leaching to rivers, or to the existence of natural sources intertwined with managed lands, or to an under-estimation of N₂O emission factors for direct agricultural soil emissions. The advantage of inversions is that they provide insights on seasonal and interannual greenhouse gas fluxes anomalies, e.g. during extreme events such as drought or abnormal fire episodes, whereas inventory methods are established to estimate trends and multi-annual changes. As a much denser sampling of atmospheric CO₂ and CH₄ concentrations by different satellites coordinated into a global constellation is expected in the coming years, the methodology proposed here to compare inversion results with inventory reports could be applied regularly for monitoring the effectiveness of mitigation policy and progress by countries to meet the objective of their pledges.

中文翻译：

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比较 UNFCCC 清单中报告的国家温室气体预算与大气逆温

摘要。为支持《巴黎气候变化协定》的全球盘点，本研究提出了一个综合框架来处理大气逆温的结果，以使其适用于评估 UNFCCC 国家土地利用二氧化碳 (CO ₂ ) 排放清单和清除，对应于土地利用、土地利用变化和林业和废物部门。我们还推断人为甲烷 (CH ₄ ) 排放重新组合为化石和农业和废物排放，以及人为一氧化二氮 (N ₂O) 倒置的排放。为了将反演与国家报告进行比较，我们编制了一个新的全球统一数据库，其中包含来自附件 I 国家定期 UNFCCC 清单的国家排放和清除，以及来自非附件 I 国家的零星和不太详细的排放报告，由国家信息通报和两年一次更新提供报告。将反演与清单相协调的方法适用于覆盖全球 78% 的 CO ₂土地碳吸收的选定大国，以及土地利用、土地利用变化和林业部门的排放和清除，以及 CH 的最大排放者₄和 N ₂O. 我们的方法使用全球碳项目为三种温室气体生成的一组全球反演结果，以及辅助数据。我们研究了由河流横向转移过程和作物和木材产品贸易引起的 CO ₂通量的作用，以及未管理土地中碳吸收的作用，两者都没有被清单规则考虑在内。在这里，我们表明，尽管在反演中存在很大差异，但可用反演模型的中位数指向比温带国家或北半球国家组（如俄罗斯、加拿大和欧盟）的库存更大的陆地碳汇。对于 CH ₄，我们发现仅同化来自全球原位网络数据的反演与使用卫星 CH ₄反演的反演之间具有良好的一致性，并且反演诊断出比清单报告的CH ₄排放估计值更高的趋势。特别是，中亚和波斯湾地区的石油和天然气开采国倾向于系统地报告与反演估计的排放量相比较低的排放量。对于 N ₂ O，即使在试图仅考虑受管理的土地排放时，倒置往往会比热带国家的清单产生更高的人为排放。在许多非附件 I 国家的清单中，这可以暂时归因于缺乏报告间接 N ₂大气沉降和河流淋滤产生的 O 排放，或与管理土地交织在一起的自然资源的存在，或对直接农业土壤排放的 N ₂ O 排放因子的低估。反演的优势在于它们提供了对季节性和年际温室气体通量异常的洞察，例如在干旱或异常火灾事件等极端事件期间，而建立清单方法来估计趋势和多年变化。作为大气 CO ₂和 CH _{4 的}密度更高的采样 预计在未来几年由不同卫星协调成一个全球星座的浓度，这里提出的将反演结果与清单报告进行比较的方法可以定期应用于监测缓解政策的有效性和各国实现其承诺目标的进展。