Comparing national greenhouse gas budgets reported in UNFCCC inventories against atmospheric inversions

Abstract. In support of the global stocktake Paris Agreement on climate change, this study presents a comprehensive framework to process results an ensemble atmospheric inversions in order make their net ecosystem exchange (NEE) carbon dioxide (CO2) flux suitable for evaluating national greenhouse gas inventories (NGHGIs) submitted by countries United Nations Framework Convention Climate Change (UNFCCC). From we also deduced anthropogenic methane (CH4) emissions regrouped into fossil and agriculture waste emissions, as well nitrous oxide (N2O) emissions. To compare inversion with reports, compiled new harmonized database removals from periodical UNFCCC Annex I countries, sporadic less detailed reports non-Annex given communications biennial update reports. No gap filling was applied. The method reconcile is applied selected large covering ?90 % land uptake CO2 top emitters CH4 N2O. Our uses produced Global Carbon Project three gases, ancillary data. We examine role fluxes caused lateral transfer processes rivers trade crop wood products unmanaged lands, both not accounted NGHGIs. Here show that, despite spread across inversions, median available models points larger terrestrial sink than over temperate or groups Northern Hemisphere like Russia, Canada European Union. For CH4, find good consistency between assimilating only data situ network those using satellite retrievals tendency diagnose higher emission estimates reported particular, oil- gas-extracting central Asia Persian Gulf region tend systematically report lower compared estimated inversions. N2O, produce tropical even when attempting consider managed many can be tentatively attributed lack reporting indirect N2O deposition leaching rivers, existence natural sources intertwined underestimation factors direct agricultural soil Inversions provide insights seasonal interannual anomalies, e.g., during extreme events such drought abnormal fire episodes, whereas inventory methods are established estimate trends multi-annual changes. As much denser sampling concentrations different satellites coordinated constellation expected coming years, methodology proposed here (e.g., NGHGIs) could regularly monitoring effectiveness mitigation policy progress meet objective pledges. dataset constructed publicly at https://doi.org/10.5281/zenodo.5089799 (Deng et al., 2021).