Articles | Volume 22, issue 20
https://doi.org/10.5194/bg-22-6017-2025
https://doi.org/10.5194/bg-22-6017-2025
Research article
 | Highlight paper
 | 
24 Oct 2025
Research article | Highlight paper |  | 24 Oct 2025

A fresh look at the pre-industrial air–sea carbon flux using the alkalinity budget

Alban Planchat, Laurent Bopp, and Lester Kwiatkowski

Related authors

Beyond wind-induced upwelling: diverse drivers of future productivity in eastern boundary upwelling systems
Erica Cioffi, Laurent Bopp, and Lester Kwiatkowski
EGUsphere, https://doi.org/10.5194/egusphere-2025-5217,https://doi.org/10.5194/egusphere-2025-5217, 2025
This preprint is open for discussion and under review for Biogeosciences (BG).
Short summary
Global Carbon Budget 2025
Pierre Friedlingstein, Michael O'Sullivan, Matthew W. Jones, Robbie M. Andrew, Dorothee C. E. Bakker, Judith Hauck, Peter Landschützer, Corinne Le Quéré, Hongmei Li, Ingrid T. Luijkx, Glen P. Peters, Wouter Peters, Julia Pongratz, Clemens Schwingshackl, Stephen Sitch, Josep G. Canadell, Philippe Ciais, Kjetil Aas, Simone R. Alin, Peter Anthoni, Leticia Barbero, Nicholas R. Bates, Nicolas Bellouin, Alice Benoit-Cattin, Carla F. Berghoff, Raffaele Bernardello, Laurent Bopp, Ida B. M. Brasika, Matthew A. Chamberlain, Naveen Chandra, Frédéric Chevallier, Louise P. Chini, Nathan O. Collier, Thomas H. Colligan, Margot Cronin, Laique Djeutchouang, Xinyu Dou, Matt P. Enright, Kazutaka Enyo, Michael Erb, Wiley Evans, Richard A. Feely, Liang Feng, Daniel J. Ford, Adrianna Foster, Filippa Fransner, Thomas Gasser, Marion Gehlen, Thanos Gkritzalis, Jefferson Goncalves De Souza, Giacomo Grassi, Luke Gregor, Nicolas Gruber, Bertrand Guenet, Özgür Gürses, Kirsty Harrington, Ian Harris, Jens Heinke, George C. Hurtt, Yosuke Iida, Tatiana Ilyina, Akihiko Ito, Andrew R. Jacobson, Atul K. Jain, Tereza Jarníková, Annika Jersild, Fei Jiang, Steve D. Jones, Etsushi Kato, Ralph F. Keeling, Kees Klein Goldewijk, Jürgen Knauer, Yawen Kong, Jan Ivar Korsbakken, Charles Koven, Taro Kunimitsu, Xin Lan, Junjie Liu, Zhiqiang Liu, Zhu Liu, Claire Lo Monaco, Lei Ma, Gregg Marland, Patrick C. McGuire, Galen A. McKinley, Joe Melton, Natalie Monacci, Erwan Monier, Eric J. Morgan, David R. Munro, Jens D. Müller, Shin-Ichiro Nakaoka, Lorna R. Nayagam, Yosuke Niwa, Tobias Nutzel, Are Olsen, Abdirahman M. Omar, Naiqing Pan, Sudhanshu Pandey, Denis Pierrot, Zhangcai Qin, Pierre A. G. Regnier, Gregor Rehder, Laure Resplandy, Alizée Roobaert, Thais M. Rosan, Christian Rödenbeck, Jörg Schwinger, Ingunn Skjelvan, T. Luke Smallman, Victoria Spada, Mohanan G. Sreeush, Qing Sun, Adrienne J. Sutton, Colm Sweeney, Didier Swingedouw, Roland Séférian, Shintaro Takao, Hiroaki Tatebe, Hanqin Tian, Xiangjun Tian, Bronte Tilbrook, Hiroyuki Tsujino, Francesco Tubiello, Erik van Ooijen, Guido van der Werf, Sebastiaan J. van de Velde, Anthony Walker, Rik Wanninkhof, Xiaojuan Yang, Wenping Yuan, Xu Yue, and Jiye Zeng
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2025-659,https://doi.org/10.5194/essd-2025-659, 2025
Preprint under review for ESSD
Short summary
Mapping the safe operating space of marine ecosystems under contrasting emission pathways
Timothée Bourgeois, Giang T. Tran, Aurich Jeltsch-Thömmes, Jörg Schwinger, Friederike Fröb, Thomas L. Frölicher, Thorsten Blenckner, Olivier Torres, Jean Negrel, David P. Keller, Andreas Oschlies, Laurent Bopp, and Fortunat Joos
Biogeosciences, 22, 5435–5462, https://doi.org/10.5194/bg-22-5435-2025,https://doi.org/10.5194/bg-22-5435-2025, 2025
Short summary
Heterogeneous future Arctic Ocean primary productivity changes projected in CMIP6
Léna L. Champiot-Bayard, Lester L. Kwiatkowski, and Martin M. Vancoppenolle
EGUsphere, https://doi.org/10.5194/egusphere-2025-4296,https://doi.org/10.5194/egusphere-2025-4296, 2025
This preprint is open for discussion and under review for Biogeosciences (BG).
Short summary
Increased future ocean heat uptake constrained by Antarctic sea ice extent
Linus Vogt, Casimir de Lavergne, Jean-Baptiste Sallée, Lester Kwiatkowski, Thomas L. Frölicher, and Jens Terhaar
Earth Syst. Dynam., 16, 1453–1482, https://doi.org/10.5194/esd-16-1453-2025,https://doi.org/10.5194/esd-16-1453-2025, 2025
Short summary

Cited articles

Aumont, O., Orr, J. C., Monfray, P., Ludwig, W., Amiotte-Suchet, P., and Probst, J.-L.: Riverine-driven interhemispheric transport of carbon, Global Biogeochemical Cycles, 15, 393–405, https://doi.org/10.1029/1999GB001238, 2001. a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p
Aumont, O., Ethé, C., Tagliabue, A., Bopp, L., and Gehlen, M.: PISCES-v2: an ocean biogeochemical model for carbon and ecosystem studies, Geosci. Model Dev., 8, 2465–2513, https://doi.org/10.5194/gmd-8-2465-2015, 2015. a
Bopp, L., Aumont, O., Kwiatkowski, L., Clerc, C., Dupont, L., Ethé, C., Gorgues, T., Séférian, R., and Tagliabue, A.: Diazotrophy as a key driver of the response of marine net primary productivity to climate change, Biogeosciences, 19, 4267–4285, https://doi.org/10.5194/bg-19-4267-2022, 2022. a
Boucher, O., Servonnat, J., Albright, A. L., Aumont, O., Balkanski, Y., Bastrikov, V., Bekki, S., Bonnet, R., Bony, S., Bopp, L., Braconnot, P., Brockmann, P., Cadule, P., Caubel, A., Cheruy, F., Codron, F., Cozic, A., Cugnet, D., D'Andrea, F., Davini, P., Lavergne, C., Denvil, S., Deshayes, J., Devilliers, M., Ducharne, A., Dufresne, J., Dupont, E., Éthé, C., Fairhead, L., Falletti, L., Flavoni, S., Foujols, M., Gardoll, S., Gastineau, G., Ghattas, J., Grandpeix, J., Guenet, B., Guez, E., L., Guilyardi, E., Guimberteau, M., Hauglustaine, D., Hourdin, F., Idelkadi, A., Joussaume, S., Kageyama, M., Khodri, M., Krinner, G., Lebas, N., Levavasseur, G., Lévy, C., Li, L., Lott, F., Lurton, T., Luyssaert, S., Madec, G., Madeleine, J., Maignan, F., Marchand, M., Marti, O., Mellul, L., Meurdesoif, Y., Mignot, J., Musat, I., Ottlé, C., Peylin, P., Planton, Y., Polcher, J., Rio, C., Rochetin, N., Rousset, C., Sepulchre, P., Sima, A., Swingedouw, D., Thiéblemont, R., Traore, A. K., Vancoppenolle, M., Vial, J., Vialard, J., Viovy, N., and Vuichard, N.: Presentation and Evaluation of the IPSL-CM6A-LR Climate Model, Journal of Advances in Modeling Earth Systems, 12, https://doi.org/10.1029/2019MS002010, 2020. a
Boudreau, B. P., Middelburg, J. J., and Luo, Y.: The role of calcification in carbonate compensation, Nature Geoscience, 11, 894–900, https://doi.org/10.1038/s41561-018-0259-5, 2018. a, b
Download
Co-editor-in-chief
Disparities in ocean carbon sink estimates derived from observations and models raise questions about our ability to accurately assess its magnitude and trend. Surface ocean pCO2-data based carbon uptake inferences are systematically higher than estimates based on global ocean biogeochemical models. River carbon inputs and carbon burial in sediments contribute largely to this difference. Hence, it is critical to accurately constrain riverine carbon inputs (in the form of inorganic and organic carbon) and burial of organic and inorganic carbon in oceanic sediments. These are non-trivial task because part, but not all, of the organic carbon delivered by rivers is degraded to inorganic carbon and because of carbonate-system re-equilibrations, including calcium carbonate precipitation and dissolution. The Planchat et al. paper presents a simple conceptual model and explores its value using full scale ocean biogeochemical models. The resulting framework is useful for future model intercomparisons and for revising pre-industrial air-sea carbon fluxes when new carbon and alkalinity budgets become available.
Short summary
Disparities between observational and model-based estimates of the ocean carbon sink persist, highlighting the need for improved understanding and methodologies to reconcile differences in both magnitude and trends over recent decades. A potential key source of uncertainty lies in the pre-industrial air–sea carbon flux, which is essential for isolating the anthropogenic component from observations. Thus, we take a fresh look at this flux using the alkalinity budget, alongside the carbon budget.
Share
Altmetrics
Final-revised paper
Preprint