EGU24-12756, updated on 09 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Identifying the origins of the global carbon budget imbalance using oxygen

Nicolas Mayot, Corinne Le Quéré, and Andrew Manning
Nicolas Mayot et al.
  • University of East Anglia, School of Environmental Sciences, Norwich, United Kingdom of Great Britain – England, Scotland, Wales (

Despite major advances in the estimation of all fluxes in the global cycles of carbon and oxygen, mathematical imbalances continue to arise when these fluxes are combined. Between 1997 and 2022, the global budget imbalances (BIM) for CO2 and O2 budgets – a quantification of the missing sources and/or sinks of CO2 and O2 – are -18 Tmol/yr and 41 Tmol/yr, respectively. The CO2 BIM has tended to become increasingly negative over the last decade, while the O2 BIM has tended to become increasingly positive. To identify the origins of the BIMs, we carried out a systematic analysis of the combination and permutation of all available individual flux estimates provided by a sub-set of contributors to the Global Carbon Budget 2023 update. We first examine the possibility that inaccuracies in the ocean air-sea fluxes contributes to the CO2 and O2 BIM. We show that the interannual variability of the air-sea O2 flux required for a reduction of the O2 BIM tends to be close to that simulated by several ocean models. An in-depth analysis of the Southern Ocean has confirmed their ability to simulate reasonable interannual variability in the air-sea fluxes of O2 and CO2. We conclude that in order to simultaneously reduce the negative trend in CO2 BIM and the positive trend in O2 BIM in the recent decade, a reduction in the increasing trend in the terrestrial CO2 sink over the last decade is most likely required.

How to cite: Mayot, N., Le Quéré, C., and Manning, A.: Identifying the origins of the global carbon budget imbalance using oxygen, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12756,, 2024.