National CO 2 budgets (2015-2020) inferred from atmospheric CO 2 observations in support of the global stocktake

Brendan Byrne , David Baker , Sourish Basu , Michael Bertolacci , Kevin Bowman , Dustin Carroll , Abhishek Chatterjee , Frédéric Chevallier (1, 2) , Philippe Ciais (1) , Noel Cressie , David Crisp , Sean Crowell , Feng Deng , Zhu Deng , Nicholas Deutscher , Manvendra Dubey , Sha Feng , Omaira García , David Griffith , Benedikt Herkommer , Lei Hu , Andrew Jacobson , Rajesh Janardanan , Sujong Jeong , Matthew Johnson , Dylan Jones , Rigel Kivi , Junjie Liu , Zhiqiang Liu , Shamil Maksyutov , John Miller , Scot Miller , Isamu Morino , Justus Notholt , Tomohiro Oda , Christopher O'Dell , Young-Suk Oh , Hirofumi Ohyama , Prabir Patra , Hélène Peiro , Christof Petri , Sajeev Philip , David Pollard , Benjamin Poulter , Marine Remaud , Andrew Schuh , Mahesh Sha , Kei Shiomi , Kimberly Strong , Colm Sweeney , Yao Té , Hanqin Tian , Voltaire Velazco , Mihalis Vrekoussis , Thorsten Warneke , John Worden , Debra Wunch , Yuanzhi Yao , Jeongmin Yun , Andrew Zammit-Mangion , Ning Zeng

1 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
2 SATINV - Modélisation INVerse pour les mesures atmosphériques et SATellitaires

Abstract. Accurate accounting of emissions and removals of CO2 is critical for the planning and verification of emission reduction targets in support of the Paris Agreement. Here, we present a pilot dataset of country-specific net carbon exchange (NCE; fossil plus terrestrial ecosystem fluxes) and terrestrial carbon stock changes aimed at informing countries' carbon budgets. These estimates are based on “top-down” NCE outputs from the v10 Orbiting Carbon Observatory (OCO-2) modeling intercomparison project (MIP), wherein an ensemble of inverse modeling groups conducted standardized experiments assimilating OCO-2 column-averaged dry-air mole fraction (XCO2) retrievals (ACOS v10), in situ CO2 measurements or combinations of these data. The v10 OCO-2 MIP NCE estimates are combined with “bottom-up” estimates of fossil fuel emissions and lateral carbon fluxes to estimate changes in terrestrial carbon stocks, which are impacted by anthropogenic and natural drivers. These flux and stock change estimates are reported annually (2015–2020) as both a global 1∘ × 1∘ gridded dataset and a country-level dataset and are available for download from the Committee on Earth Observation Satellites' (CEOS) website: https://doi.org/10.48588/npf6-sw92 (Byrne et al., 2022). Across the v10 OCO-2 MIP experiments, we obtain increases in the ensemble median terrestrial carbon stocks of 3.29–4.58 Pg CO2 yr−1 (0.90–1.25 Pg C yr−1). This is a result of broad increases in terrestrial carbon stocks across the northern extratropics, while the tropics generally have stock losses but with considerable regional variability and differences between v10 OCO-2 MIP experiments. We discuss the state of the science for tracking emissions and removals using top-down methods, including current limitations and future developments towards top-down monitoring and verification systems.

Domaines: Planète et Univers [physics]

Brendan Byrne, David Baker, Sourish Basu, Michael Bertolacci, Kevin Bowman, et al.. National CO 2 budgets (2015-2020) inferred from atmospheric CO 2 observations in support of the global stocktake. Earth System Science Data, 2023, 15 (2), pp.963-1004. ⟨10.5194/essd-15-963-2023⟩. ⟨hal-04047657⟩