Articles | Volume 22, issue 1
https://doi.org/10.5194/os-22-225-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-22-225-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| Highlight paper
| 
20 Jan 2026
Research article | Highlight paper |
| 20 Jan 2026
| 20 Jan 2026
Remineralisation changes dominate oxygen variability in the North Atlantic
NORCE Research AS, Bjerknes Centre for Climate Research, Bergen, Norway
now at: British Antarctic Survey, Cambridge, UK
Elaine L. McDonagh
NORCE Research AS, Bjerknes Centre for Climate Research, Bergen, Norway
National Oceanography Centre, Southampton, UK
Siv K. Lauvset
NORCE Research AS, Bjerknes Centre for Climate Research, Bergen, Norway
Charles E. Turner
ACCESS-NRI, Australian National University, Canberra, Australia
Thomas W. N. Haine
Department of Earth & Planetary Sciences, Johns Hopkins University, Baltimore, Maryland, USA
Nadine Goris
NORCE Research AS, Bjerknes Centre for Climate Research, Bergen, Norway
Richard Sanders
NORCE Research AS, Bjerknes Centre for Climate Research, Bergen, Norway
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Charles E. Turner, Peter J. Brown, Kevin I. C. Oliver, and Elaine L. McDonagh
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Pierre Friedlingstein, Matthew W. Jones, Michael O'Sullivan, Robbie M. Andrew, Dorothee C. E. Bakker, Judith Hauck, Corinne Le Quéré, Glen P. Peters, Wouter Peters, Julia Pongratz, Stephen Sitch, Josep G. Canadell, Philippe Ciais, Rob B. Jackson, Simone R. Alin, Peter Anthoni, Nicholas R. Bates, Meike Becker, Nicolas Bellouin, Laurent Bopp, Thi Tuyet Trang Chau, Frédéric Chevallier, Louise P. Chini, Margot Cronin, Kim I. Currie, Bertrand Decharme, Laique M. Djeutchouang, Xinyu Dou, Wiley Evans, Richard A. Feely, Liang Feng, Thomas Gasser, Dennis Gilfillan, Thanos Gkritzalis, Giacomo Grassi, Luke Gregor, Nicolas Gruber, Özgür Gürses, Ian Harris, Richard A. Houghton, George C. Hurtt, Yosuke Iida, Tatiana Ilyina, Ingrid T. Luijkx, Atul Jain, Steve D. Jones, Etsushi Kato, Daniel Kennedy, Kees Klein Goldewijk, Jürgen Knauer, Jan Ivar Korsbakken, Arne Körtzinger, Peter Landschützer, Siv K. Lauvset, Nathalie Lefèvre, Sebastian Lienert, Junjie Liu, Gregg Marland, Patrick C. McGuire, Joe R. Melton, David R. Munro, Julia E. M. S. Nabel, Shin-Ichiro Nakaoka, Yosuke Niwa, Tsuneo Ono, Denis Pierrot, Benjamin Poulter, Gregor Rehder, Laure Resplandy, Eddy Robertson, Christian Rödenbeck, Thais M. Rosan, Jörg Schwinger, Clemens Schwingshackl, Roland Séférian, Adrienne J. Sutton, Colm Sweeney, Toste Tanhua, Pieter P. Tans, Hanqin Tian, Bronte Tilbrook, Francesco Tubiello, Guido R. van der Werf, Nicolas Vuichard, Chisato Wada, Rik Wanninkhof, Andrew J. Watson, David Willis, Andrew J. Wiltshire, Wenping Yuan, Chao Yue, Xu Yue, Sönke Zaehle, and Jiye Zeng
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Filippa Fransner, Friederike Fröb, Jerry Tjiputra, Nadine Goris, Siv K. Lauvset, Ingunn Skjelvan, Emil Jeansson, Abdirahman Omar, Melissa Chierici, Elizabeth Jones, Agneta Fransson, Sólveig R. Ólafsdóttir, Truls Johannessen, and Are Olsen
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Ocean acidification, a direct consequence of the CO2 release by human activities, is a serious threat to marine ecosystems. In this study, we conduct a detailed investigation of the acidification of the Nordic Seas, from 1850 to 2100, by using a large set of samples taken during research cruises together with numerical model simulations. We estimate the effects of changes in different environmental factors on the rate of acidification and its potential effects on cold-water corals.
Siv K. Lauvset, Nico Lange, Toste Tanhua, Henry C. Bittig, Are Olsen, Alex Kozyr, Marta Álvarez, Susan Becker, Peter J. Brown, Brendan R. Carter, Leticia Cotrim da Cunha, Richard A. Feely, Steven van Heuven, Mario Hoppema, Masao Ishii, Emil Jeansson, Sara Jutterström, Steve D. Jones, Maren K. Karlsen, Claire Lo Monaco, Patrick Michaelis, Akihiko Murata, Fiz F. Pérez, Benjamin Pfeil, Carsten Schirnick, Reiner Steinfeldt, Toru Suzuki, Bronte Tilbrook, Anton Velo, Rik Wanninkhof, Ryan J. Woosley, and Robert M. Key
Earth Syst. Sci. Data, 13, 5565–5589, https://doi.org/10.5194/essd-13-5565-2021, https://doi.org/10.5194/essd-13-5565-2021, 2021
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GLODAP is a data product for ocean inorganic carbon and related biogeochemical variables measured by the chemical analysis of water bottle samples from scientific cruises. GLODAPv2.2021 is the third update of GLODAPv2 from 2016. The data that are included have been subjected to extensive quality control, including systematic evaluation of measurement biases. This version contains data from 989 hydrographic cruises covering the world's oceans from 1972 to 2020.
Alice Marzocchi, A. J. George Nurser, Louis Clément, and Elaine L. McDonagh
Ocean Sci., 17, 935–952, https://doi.org/10.5194/os-17-935-2021, https://doi.org/10.5194/os-17-935-2021, 2021
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The ocean absorbs a large proportion of the excess heat and anthropogenic carbon in the climate system. This uptake is modulated by air–sea fluxes and by the processes that transport water from the surface into the ocean’s interior. We performed numerical simulations with interannually varying passive tracers and identified the key role of surface atmospheric forcing in setting the longer-term variability in the distribution of the tracers after they are transported below the ocean’s surface.
Cited articles
Abe, Y. and Minobe, S.: Comparison of ocean deoxygenation between CMIP models and an observational dataset in the North Pacific from 1958 to 2005, Front. Mar. Sci., 10, 1161451, https://doi.org/10.3389/fmars.2023.1161451, 2023. a
Barth, A., Beckers, J.-M., Troupin, C., Alvera-Azcárate, A., and Vandenbulcke, L.: divand-1.0: n-dimensional variational data analysis for ocean observations, Geosci. Model Dev., 7, 225–241, https://doi.org/10.5194/gmd-7-225-2014, 2014. a
Bindoff, N. L. and Mcdougall, T. J.: Diagnosing climate change and ocean ventilation using hydrographic data, J. Phys. Oceanogr., 24, 1137–1152, https://doi.org/10.1175/1520-0485(1994)024<1137:DCCAOV>2.0.CO;2, 1994. a
Bopp, L., Resplandy, L., Orr, J. C., Doney, S. C., Dunne, J. P., Gehlen, M., Halloran, P., Heinze, C., Ilyina, T., Seferian, R., Tjiputra, J., and Vichi, M.: Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models, Biogeosciences, 10, 6225–6245, https://doi.org/10.5194/bg-10-6225-2013, 2013. a, b
Breitburg, D., Levin, L. A., Oschlies, A., Grégoire, M., Chavez, F. P., Conley, D. J., Garçon, V., Gilbert, D., Gutiérrez, D., Isensee, K., Jacinto, G. S., Limburg, K. E., Montes, I., , Naqvi, S. W. A., Pitcher, G. C., Rabalais, N. N., Roman, M. R., Rose, K. A., Seibel, B. A., Telszewski, M., Yasuhara, M., and Zhang, J.: Declining oxygen in the global ocean and coastal waters, Science, 359, eaam7240, https://doi.org/10.1126/science.aam7240, 2018. a
Brewer, P. G. and Peltzer, E. T.: Depth perception: the need to report ocean biogeochemical rates as functions of temperature, not depth, Philos. T. Roy. Soc. A, 375, 20160319, https://doi.org/10.1098/rsta.2016.0319, 2017. a
Bronselaer, B. and Zanna, L.: Heat and carbon coupling reveals ocean warming due to circulation changes, Nature, 584, 227–233, https://doi.org/10.1038/s41586-020-2573-5, 2020. a, b
Buchanan, P. J. and Tagliabue, A.: The regional importance of oxygen demand and supply for historical ocean oxygen trends, Geophys. Res. Lett., 48, e2021GL094797, https://doi.org/10.1029/2021GL094797, 2021. a
Cassar, N., Nicholson, D., Khatiwala, S., and Cliff, E.: Decomposing the oxygen signal in the ocean interior: Beyond decomposing organic matter, Geophys. Res. Lett., 48, e2021GL092621, https://doi.org/10.1029/2021GL092621, 2021. a
Desbruyères, D., McDonagh, E. L., King, B. A., and Thierry, V.: Global and full-depth ocean temperature trends during the early twenty-first century from Argo and repeat hydrography, J. Climate, 30, 1985–1997, https://doi.org/10.1175/JCLI-D-16-0396.1, 2017. a
Diaz, R. J. and Rosenberg, R.: Spreading dead zones and consequences for marine ecosystems, science, 321, 926–929, https://doi.org/10.1126/science.1156401, 2008. a
Frajka-Williams, E., Ansorge, I. J., Baehr, J., Bryden, H. L., Chidichimo, M. P., Cunningham, S. A., Danabasoglu, G., Dong, S., Donohue, K. A., Elipot, S., Heimbach, P., Holliday, N. P., Hummels, R., Jackson, L. C., Karstensen, J., Lankhorst, M., Le Bras, I. A., Lozier, M. S., McDonagh, E. L., Meinen, C. S., Mercier, H., Moat, B. I., Perez, R. C., Piecuch, C. G., Rhein, M., Srokosz, M. A., Trenberth, K. E., Bacon, S., Forget, G., Goni, G., Kieke, D., Koelling, J., Lamont, T., McCarthy, G. D., Mertens, C., Send, U., Smeed, D. A., Speich, S., van den Berg, M., Volkov, D., and Wilson, C.: Atlantic meridional overturning circulation: Observed transport and variability, Front. Mar. Sci., 6, 260, https://doi.org/10.3389/fmars.2019.00260, 2019. a
Gruber, N.: Warming up, turning sour, losing breath: ocean biogeochemistry under global change, Philos. T. Roy. Soc. A, 369, 1980–1996, https://doi.org/10.1098/rsta.2011.0003, 2011. a
Guallart, E. F., Schuster, U., Fajar, N. M., Legge, O., Brown, P., Pelejero, C., Messias, M.-J., Calvo, E., Watson, A., Ríos, A. F., and Pérez, F. F.: Trends in anthropogenic CO2 in water masses of the Subtropical North Atlantic Ocean, Prog. Oceanogr., 131, 21–32, https://doi.org/10.1016/j.pocean.2014.11.006, 2015. a, b
Helm, K. P., Bindoff, N. L., and Church, J. A.: Observed decreases in oxygen content of the global ocean, Geophys. Res. Lett., 38, https://doi.org/10.1029/2011GL049513, 2011. a, b
Hernández-Guerra, A., Pelegrí, J. L., Fraile-Nuez, E., Benítez-Barrios, V., Emelianov, M., Pérez-Hernández, M. D., and Vélez-Belchí, P.: Meridional overturning transports at 7.5N and 24.5N in the Atlantic Ocean during 1992–93 and 2010–11, Prog. Oceanogr., 128, 98–114, https://doi.org/10.1016/j.pocean.2014.08.016, 2014. a
Ito, T., Follows, M., and Boyle, E.: Is AOU a good measure of respiration in the oceans?, Geophys. Res. Lett., 31, https://doi.org/10.1029/2004GL020900, 2004. a
Ito, T., Minobe, S., Long, M. C., and Deutsch, C.: Upper ocean O2 trends: 1958–2015, Geophys. Res. Lett., 44, 4214–4223, https://doi.org/10.1002/2017GL073613, 2017. a
Johns, W. E., Elipot, S., Smeed, D. A., Moat, B., King, B., Volkov, D. L., and Smith, R. H.: Towards two decades of Atlantic Ocean mass and heat transports at 26.5° N, Philos. T. Roy. Soc. A, 381, 20220188, https://doi.org/10.1098/rsta.2022.0188, 2023. a
Katsumata, K., Purkey, S., Cowley, R., Sloyan, B., Diggs, S., Moore, T., Talley, L., and Swift, J.: GO-SHIP Easy Ocean: Formatted and gridded ship-based hydrographic section data (2024UpdateBugfix1), Zenodo [data set], https://doi.org/10.5281/zenodo.13315689, 2024. a, b
Keeling, R. F., Körtzinger, A., and Gruber, N.: Ocean deoxygenation in a warming world, Annu. Rev. Mar. Sci, 2, 199–229, https://doi.org/10.1146/annurev.marine.010908.163855, 2010. a, b, c
Key, R. M., Olsen, A., van Heuven, S., Lauvset, S. K., Velo, A., Lin, X., Schirnick, C., Kozyr, A., Tanhua, T., Hoppema, M., Jutterström, S., Steinfeldt, R., Jeansson, E., Ishii, M., Perez, F. F., and Suzuki, T.: Global ocean data analysis project, version 2 (GLODAPv2), Ornl/Cdiac-162, Ndp-093, NOAA, https://doi.org/10.3334/CDIAC/OTG.NDP093_GLODAPv2, 2015. a
Langdon, C.: Determination of Dissolved Oxygen in Seawater By Winkler Titration using Amperometric Technique, in: The GO-SHIP Repeat Hydrography Manual: A Collection of Expert Reports and Guidelines. Version 1, edited by: Hood, E. M., Sabine, C. L., and Sloyan, B. M., 18 pp., IOCCP Report Number 14, ICPO Publication Series Number 134, https://doi.org/10.25607/OBP-1350, 2010. a, b
Lauvset, S. K., Lange, N., Tanhua, T., Bittig, H. C., Olsen, A., Kozyr, A., Alin, S., Álvarez, M., Azetsu-Scott, K., Barbero, L., Becker, S., Brown, P. J., Carter, B. R., da Cunha, L. C., Feely, R. A., Hoppema, M., Humphreys, M. P., Ishii, M., Jeansson, E., Jiang, L.-Q., Jones, S. D., Lo Monaco, C., Murata, A., Müller, J. D., Pérez, F. F., Pfeil, B., Schirnick, C., Steinfeldt, R., Suzuki, T., Tilbrook, B., Ulfsbo, A., Velo, A., Woosley, R. J., and Key, R. M.: GLODAPv2.2022: the latest version of the global interior ocean biogeochemical data product, Earth Syst. Sci. Data, 14, 5543–5572, https://doi.org/10.5194/essd-14-5543-2022, 2022. a, b, c
Levin, L. A.: Manifestation, drivers, and emergence of open ocean deoxygenation, Annu. Rev. Mar. Sci., 10, 229–260, https://doi.org/10.1146/annurev-marine-121916-063359, 2018. a
Li, Y.-H. and Peng, T.-H.: Latitudinal change of remineralization ratios in the oceans and its implication for nutrient cycles, Global Biogeochem. Cy., 16, 77-1–77-16, https://doi.org/10.1029/2001GB001828, 2002. a
Long, M. C., Deutsch, C., and Ito, T.: Finding forced trends in oceanic oxygen, Global Biogeochem. Cy., 30, 381–397, https://doi.org/10.1002/2015GB005310, 2016. a
Macovei, V., Torres-Valdés, S., Hartman, S., Schuster, U., Moore, C., Brown, P., Hydes, D., and Sanders, R.: Temporal variability in the nutrient biogeochemistry of the surface North Atlantic: 15 years of ship of opportunity data, Global Biogeochem. Cy., 33, 1674–1692, https://doi.org/10.1029/2018GB006132, 2019. a
Matear, R. and Hirst, A.: Long-term changes in dissolved oxygen concentrations in the ocean caused by protracted global warming, Global Biogeochem. Cy., 17, https://doi.org/10.1029/2002GB001997, 2003. a
Morée, A. L., Clarke, T. M., Cheung, W. W., and Frölicher, T. L.: Impact of deoxygenation and warming on global marine species in the 21st century, Biogeosciences, 20, 2425–2454, https://doi.org/10.5194/bg-20-2425-2023, 2023. a
NOAA National Centers for Environmental Information: ETOPO 2022 15 Arc-Second Global Relief Model, NOAA National Centers for Environmental Information [data set], https://doi.org/10.25921/fd45-gt74, 2022. a
Olsen, A., Key, R. M., Van Heuven, S., Lauvset, S. K., Velo, A., Lin, X., Schirnick, C., Kozyr, A., Tanhua, T., Hoppema, M., Jutterström, S., Steinfeldt, R., Jeansson, E., Ishii, M., Pérez, F. F., and Suzuki, T.: The Global Ocean Data Analysis Project version 2 (GLODAPv2) – an internally consistent data product for the world ocean, Earth Syst. Sci. Data, 8, 297–323, https://doi.org/10.5194/essd-8-297-2016, 2016. a, b
Oschlies, A.: A committed fourfold increase in ocean oxygen loss, Nat. Commun., 12, 1–8, https://doi.org/10.1038/s41467-021-22584-4, 2021. a, b, c
Oschlies, A., Duteil, O., Getzlaff, J., Koeve, W., Landolfi, A., and Schmidtko, S.: Patterns of deoxygenation: sensitivity to natural and anthropogenic drivers, Philos. T. Roy. Soc. A, 375, 20160325, https://doi.org/10.1098/rsta.2016.0325, 2017. a, b
Oschlies, A., Brandt, P., Stramma, L., and Schmidtko, S.: Drivers and mechanisms of ocean deoxygenation, Nat. Geosci., 11, 467–473, https://doi.org/10.1038/s41561-018-0152-2, 2018. a, b
Palter, J. B. and Trossman, D. S.: The sensitivity of future ocean oxygen to changes in ocean circulation, Global Biogeochem. Cy., 32, 738–751, https://doi.org/10.1002/2017GB005777, 2018. a
Redfield, A. C.: On the Proportions of Organic Derivatives in Sea Water and Their Relation to the Composition of Plankton, James Johnstone Memorial Volume, University Press of Liverpool, 176–192, 1934. a
Redfield, A. C.: The biological control of chemical factors in the environment, Am. Scient., 46, 230A, 205–221, 1958. a
Schmidtko, S., Stramma, L., and Visbeck, M.: Decline in global oceanic oxygen content during the past five decades, Nature, 542, 335–339, https://doi.org/10.1038/nature21399, 2017. a, b
Shaffer, G., Olsen, S. M., and Pedersen, J. O. P.: Long-term ocean oxygen depletion in response to carbon dioxide emissions from fossil fuels, Nat. Geosci., 2, 105–109, https://doi.org/10.1038/ngeo420, 2009. a
Smeed, D. A., McCarthy, G., Cunningham, S. A., Frajka-Williams, E., Rayner, D., Johns, W., Meinen, C. S., Baringer, M. O., Moat, B. I., Duchez, A., and Bryden, H. L.: Observed decline of the Atlantic meridional overturning circulation 2004–2012, Ocean Sci., 10, 29–38, https://doi.org/10.5194/os-10-29-2014, 2014. a
Stendardo, I. and Gruber, N.: Oxygen trends over five decades in the North Atlantic, J. Geophys. Res.-Oceans, 117, https://doi.org/10.1029/2012JC007909, 2012. a, b
Stramma, L., Johnson, G. C., Sprintall, J., and Mohrholz, V.: Expanding oxygen-minimum zones in the tropical oceans, Science, 320, 655–658, https://doi.org/10.1126/science.1156401, 2008. a
Takano, Y., Ilyina, T., Tjiputra, J., Eddebbar, Y. A., Berthet, S., Bopp, L., Buitenhuis, E., Butenschön, M., Christian, J. R., Dunne, J. P., Gröger, M., Hayashida, H., Hieronymus, J., Koenigk, T., Krasting, J. P., Long, M. C., Lovato, T., Nakano, H., Palmieri, J., Schwinger, J., Séférian, R., Suntharalingam, P., Tatebe, H., Tsujino, H., Urakawa, S., Watanabe, M., and Yool, A.: Simulations of ocean deoxygenation in the historical era: insights from forced and coupled models, Front. Mar. Sci., 10, 1139917, https://doi.org/10.3389/fmars.2023.1139917, 2023. a
Turner, C. E., Brown, P. J., Oliver, K. I., and McDonagh, E. L.: Decomposing oceanic temperature and salinity change using ocean carbon change, Ocean Sci., 18, 523–548, https://doi.org/10.5194/os-18-523-2022, 2022. a, b
Wilson, J. D., Andrews, O., Katavouta, A., de Melo Viríssimo, F., Death, R. M., Adloff, M., Baker, C. A., Blackledge, B., Goldsworth, F. W., Kennedy-Asser, A. T., Liu, Q., Sieradzan, K. R., Vosper, E., and Ying, R.: The biological carbon pump in CMIP6 models: 21st century trends and uncertainties, P. Natl. Acad. Sci. USA, 119, e2204369119, https://doi.org/10.1073/pnas.2204369119, 2022. a
Wunsch, C.: Discrete inverse and state estimation problems: with geophysical fluid applications, Cambridge University Press, https://eprints.soton.ac.uk/498514/ (last access: January 2025), 2006. a
Zika, J. D., Gregory, J. M., McDonagh, E. L., Marzocchi, A., and Clément, L.: Recent water mass changes reveal mechanisms of ocean warming, J. Climate, 34, 3461–3479, https://doi.org/10.1175/JCLI-D-20-0355.1, 2021. a, b
Co-editor-in-chief
Oxygen is fundamental to ocean biogeochemical processes, with deoxygenation potentially reducing biodiversity, and disrupting biogeochemical cycles. This paper develops and implements a new inverse method to decompose oxygen change into its constituent parts by linking each process to concomitant changes in temperature and dissolved inorganic carbon (DIC). They apply this method to a GO-SHIP repeated section of the North Atlantic Ocean. They find that alterations in remineralisation, either local or upstream, are responsible for up to half of the total oxygen decrease seen in the upper 2000 m between 1992 and 2015. This method could be repeated on any dataset, observations or model, that includes temperature, DIC, and oxygen concentration data.
Oxygen is fundamental to ocean biogeochemical processes, with deoxygenation potentially reducing...
Short summary
Oxygen is essential to marine life, but the amount of oxygen in the ocean has been decreasing in recent decades. Using observations of oxygen concentration interpolated across a section of the subtropical North Atlantic Ocean, we show that deoxygenation in the region is primarily driven by an increase in oxygen being consumed during remineralisation of organic matter. The impact of this is strongest at depths of around 600 m, where the process drives up to 70 % of the total deoxygenation.
Oxygen is essential to marine life, but the amount of oxygen in the ocean has been decreasing in...
