Climate-driven variability of the Southern Ocean CO2 sink
Creators
- 1. Centre for Ocean and Atmospheric Sciences, School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK
- 2. Max Planck Institute for Biogeochemistry, PO Box 600164, Hans-Knöll-Str. 10, 07745 Jena, Germany
- 3. Department of Earth Sciences, Barcelona Supercomputing Center, Barcelona, Catalonia, Spain
- 4. Laboratoire de Météorologie Dynamique/Institut Pierre-Simon Laplace, CNRS, Ecole Normale Supérieure/Université PSL, Sorbonne Université, Ecole Polytechnique, Paris, France
- 5. Department of Oceanography, University of Cape Town, Cape Town 7701, South Africa
- 6. Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
- 7. Environmental Physics, ETH Zürich, Institute of Biogeochemistry and Pollutant Dynamics and Center for Climate Systems Modeling (C2SM), Zurich, Switzerland
- 8. Alfred-Wegener-Institut Helmholtz-Zentum für Polar- und Meeresforschung, Postfach 120161, 27515 Bremerhaven, Germany
- 9. Atmosphere and Ocean Department, Japan Meteorological Agency, 1-3-4 Otemachi, Chiyoda-Ku, Tokyo 100-8122, Japan
- 10. Max Planck Institute for Meteorology, Hamburg, Germany
- 11. cripps Institution of Oceanography, University of California, San Diego, CA, USA
- 12. Flanders Marine Institute (VLIZ), Jacobsenstraat 1, 8400 Ostend, Belgium
- 13. GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
- 14. Department of Geosciences and High Meadows Environmental Institute, Princeton University, Princeton, NJ, USA
- 15. NORCE Norwegian Research Centre, Jahnebakken 5, 5007 Bergen, Norway
- 16. CNRM, Université de Toulouse, Météo-France, CNRS, Toulouse, France
- 17. College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4RJ, UK
- 18. Earth System Division, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
Description
Climate-driven variability of the Southern Ocean CO2 sink
The Southern Ocean is a major sink of atmospheric CO2, but the nature and magnitude of its variability remains uncertain and debated. Estimates based on observations suggest substantial variability that is not reproduced by process-based ocean models, with increasingly divergent estimates over the past decade. We examine potential constraints on the nature and magnitude of climate-driven variability of the Southern Ocean CO2 sink from observation- based air–sea O2 fluxes. On interannual time scales, the variability in the air–sea fluxes of CO2 and O2 estimated from observations is consistent across the two species and positively correlated with the variability simulated by ocean models. Our analysis suggests that variations in ocean ventilation related to the Southern Annular Mode are responsible for this interannual variability. On decadal time scales, the existence of significant variability in the air–sea CO2 flux estimated from observations also tends to be supported by observation- based estimates of O2 flux variability. However, the large decadal variability in air–sea CO2 flux is absent from ocean models. Our analysis suggests that issues in representing the balance between the thermal and non-thermal components of the CO2 sink and/or insufficient variability in mode water formation might contribute to the lack of decadal variability in the current generation of ocean models.
This article is part of a discussion meeting issue ’Heat and carbon uptake in the Southern Ocean: the state of the art and future priorities’.
Files
rsta.2022.0055.pdf
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