Global cooling linked to increased glacial carbon storage via changes in Antarctic sea ice

Article metrics


Palaeo-oceanographic reconstructions indicate that the distribution of global ocean water masses has undergone major glacial–interglacial rearrangements over the past ~2.5 million years. Given that the ocean is the largest carbon reservoir, such circulation changes were probably key in driving the variations in atmospheric CO2 concentrations observed in the ice-core record. However, we still lack a mechanistic understanding of the ocean’s role in regulating CO2 on these timescales. Here, we show that glacial ocean–sea ice numerical simulations with a single-basin general circulation model, forced solely by atmospheric cooling, can predict ocean circulation patterns associated with increased atmospheric carbon sequestration in the deep ocean. Under such conditions, Antarctic bottom water becomes more isolated from the sea surface as a result of two connected factors: reduced air–sea gas exchange under sea ice around Antarctica and weaker mixing with North Atlantic Deep Water due to a shallower interface between southern- and northern-sourced water masses. These physical changes alone are sufficient to explain ~40 ppm atmospheric CO2 drawdown—about half of the glacial–interglacial variation. Our results highlight that atmospheric cooling could have directly caused the reorganization of deep ocean water masses and, thus, glacial CO2 drawdown. This provides an important step towards a consistent picture of glacial climates.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Changes in ocean circulation and sea ice cover between the PI and LGM.
Fig. 2: Deep ocean carbon storage and atmospheric CO2 concentrations in the PI and LGM reference simulations.

Data availability

The input files used to run the MITgcm simulations that support the findings of this study are available from the corresponding author upon request. The model output data for all simulations can be obtained from

Code availability

The MITgcm code is freely available for download at Computer code used to process the model output and generate figures is available from the corresponding author on request.


  1. 1.

    Sigman, D. M. & Boyle, E. A. Glacial/interglacial variations in atmospheric carbon dioxide. Nature 407, 859–869 (2000).

  2. 2.

    Brovkin, V., Ganopolski, A., Archer, D. & Rahmstorf, S. Lowering of glacial atmospheric CO2 in response to changes in oceanic circulation and marine biogeochemistry. Paleoceanography 22, PA4202 (2007).

  3. 3.

    Marshall, J. & Speer, K. Closure of the meridional overturning circulation through Southern Ocean upwelling. Nat. Geosci. 5, 171–180 (2012).

  4. 4.

    Marchitto, T. M., Oppo, D. W. & Curry, W. B. Paired benthic foraminiferal Cd/Ca and Zn/Ca evidence for a greatly increased presence of Southern Ocean Water in the glacial North Atlantic. Paleoceanography 17, 10–11 (2002).

  5. 5.

    Curry, W. B. & Oppo, D. W. Glacial water mass geometry and the distribution of δ13C of ∑CO2 in the western Atlantic Ocean. Paleoceanography 20, PA1017 (2005).

  6. 6.

    Lippold, J. et al. Strength and geometry of the glacial Atlantic meridional overturning circulation. Nat. Geosci. 5, 813–816 (2012).

  7. 7.

    Adkins, J. F., McIntyre, K. & Schrag, D. P. The salinity, temperature, and δ18O of the glacial deep ocean. Science 298, 1769–1773 (2002).

  8. 8.

    Insua, T. L., Spivack, A. J., Graham, D., D’Hondt, S. & Moran, K. Reconstruction of Pacific Ocean bottom water salinity during the last glacial maximum. Geophys. Res. Lett. 41, 2914–2920 (2014).

  9. 9.

    Wunsch, C. Pore fluids and the LGM ocean salinity reconsidered. Quat. Sci. Rev. 135, 154–170 (2016).

  10. 10.

    Otto-Bliesner, B. L. et al. Last glacial maximum ocean thermohaline circulation: PMIP2 model intercomparisons and data constraints. Geophys. Res. Lett. 34, L12706 (2007).

  11. 11.

    Muglia, J. & Schmittner, A. Glacial Atlantic overturning increased by wind stress in climate models. Geophys. Res. Lett. 42, 9862–9868 (2015).

  12. 12.

    Marzocchi, A. & Jansen, M. F. Connecting Antarctic sea ice to deep-ocean circulation in modern and glacial climate simulations. Geophys. Res. Lett. 44, 6286–6295 (2017).

  13. 13.

    Stephens, B. B. & Keeling, R. F. The influence of Antarctic sea ice on glacial–interglacial CO2 variations. Nature 404, 171–174 (2000).

  14. 14.

    Shin, S.-I. et al. A simulation of the last glacial maximum climate using the NCAR-CCSM. Clim. Dyn. 20, 127–151 (2003).

  15. 15.

    Bouttes, N., Paillard, D. & Roche, D. M. Impact of brine-induced stratification on the glacial carbon cycle. Clim. Past 6, 575–589 (2010).

  16. 16.

    Watson, A. J. & Naveira Garabato, A. C. The role of Southern Ocean mixing and upwelling in glacial–interglacial atmospheric CO2 change. Tellus B Chem. Phys. Meteorol. 58, 73–87 (2006).

  17. 17.

    Ferrari, R. et al. Antarctic sea ice control on ocean circulation in present and glacial climates. Proc. Natl Acad. Sci. USA 111, 8753–8758 (2014).

  18. 18.

    Jansen, M. F. Glacial ocean circulation and stratification explained by reduced atmospheric temperature. Proc. Natl Acad. Sci. USA 114, 45–50 (2017).

  19. 19.

    Sun, S., Eisenman, I. & Stewart, A. L. The influence of Southern Ocean surface buoyancy forcing on glacial–interglacial changes in the global deep ocean stratification. Geophys. Res. Lett. 43, 8124–8132 (2016).

  20. 20.

    Galbraith, E. & de Lavergne, C. Response of a comprehensive climate model to a broad range of external forcings: relevance for deep ocean ventilation and the development of late Cenozoic ice ages. Clim. Dyn. 52, 653–679 (2019).

  21. 21.

    Nadeau, L.-P., Ferrari, R. & Jansen, M. F. Antarctic sea ice control on the depth of North Atlantic Deep Water. J. Clim. 32, 2537–2551 (2019).

  22. 22.

    Jansen, M. F. & Nadeau, L.-P. The effect of southern ocean surface buoyancy loss on the deep-ocean circulation and stratification. J. Phys. Oceanogr. 46, 3455–3470 (2016).

  23. 23.

    Sarmiento, J. L. & Toggweiler, J. A new model for the role of the oceans in determining atmospheric pCO2. Nature 308, 621–624 (1984).

  24. 24.

    Archer, D. E. et al. Atmospheric pCO2 sensitivity to the biological pump in the ocean. Glob. Biogeochem. Cycles 14, 1219–1230 (2000).

  25. 25.

    Ito, T. & Follows, M. J. Preformed phosphate, soft tissue pump and atmospheric CO2. J. Mar. Res. 63, 813–839 (2005).

  26. 26.

    Kohfeld, K. E. & Ridgwell, A. Glacial–interglacial variability in atmospheric CO2. Surf. Ocean Low Atmosphere Process. 187, 251–286 (2009).

  27. 27.

    Watson, A. J., Vallis, G. K. & Nikurashin, M. Southern Ocean buoyancy forcing of ocean ventilation and glacial atmospheric CO2. Nat. Geosci. 8, 861–864 (2015).

  28. 28.

    Ganopolski, A. & Brovkin, V. Simulation of climate, ice sheets and CO2 evolution during the last four glacial cycles with an Earth system model of intermediate complexity. Climate 13, 1695–1716 (2017).

  29. 29.

    Ferreira, D., Marshall, J., Ito, T. & McGee, D. Linking glacial–interglacial states to multiple equilibria of climate. Geophys. Res. Lett. 45, 9160–9170 (2018).

  30. 30.

    Gersonde, R., Crosta, X., Abelmann, A. & Armand, L. Sea-surface temperature and sea ice distribution of the southern ocean at the EPILOG last glacial maximum—a circum-Antarctic view based on siliceous microfossil records. Quat. Sci. Rev. 24, 869–896 (2005).

  31. 31.

    Lund, D., Adkins, J. & Ferrari, R. Abyssal atlantic circulation during the Last Glacial Maximum: constraining the ratio between transport and vertical mixing. Paleoceanography 26, PA1213 (2011).

  32. 32.

    Dutkiewicz, S., Follows, M. J. & Parekh, P. Interactions of the iron and phosphorus cycles: a three-dimensional model study. Glob. Biogeochem. Cycles 19, GB1021 (2005).

  33. 33.

    Parekh, P., Follows, M. J., Dutkiewicz, S. & Ito, T. Physical and biological regulation of the soft tissue carbon pump. Paleoceanogr. Paleoclimatol. 21, PA3001 (2006).

  34. 34.

    Petit, J.-R. et al. Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature 399, 429–436 (1999).

  35. 35.

    Goodwin, P., Follows, M. J. & Williams, R. G. Analytical relationships between atmospheric carbon dioxide, carbon emissions and ocean processes. Glob. Biogeochem. Cycles 22, GB3030 (2008).

  36. 36.

    Lauderdale, J. M., Garabato, A. C. N., Oliver, K. I., Follows, M. J. & Williams, R. G. Wind-driven changes in Southern Ocean residual circulation, ocean carbon reservoirs and atmospheric CO2. Clim. Dyn. 41, 2145–2164 (2013).

  37. 37.

    Munday, D., Johnson, H. & Marshall, D. Impacts and effects of mesoscale ocean eddies on ocean carbon storage and atmospheric pCO2. Glob. Biogeochem. Cycles 28, 877–896 (2014).

  38. 38.

    Follows, M. J., Ito, T. & Marotzke, J. The wind-driven, subtropical gyres and the solubility pump of CO2. Glob. Biogeochem. Cycles 16, 1113 (2002).

  39. 39.

    Toggweiler, J., Gnanadesikan, A., Carson, S., Murnane, R. & Sarmiento, J. Representation of the carbon cycle in box models and GCMs: 1. Solubility pump. Glob. Biogeochem. Cycles 17, 1026 (2003).

  40. 40.

    Foster, T. D. An analysis of the cabbeling instability in sea water. J. Phys. Oceanogr. 2, 294–301 (1972).

  41. 41.

    Khatiwala, S., Schmittner, A. & Muglia, J. Air–sea disequilibrium enhances ocean carbon storage during glacial periods. Sci. Adv. 5, eaaw4981 (2019).

  42. 42.

    Green, J. et al. Tidal mixing and the meridional overturning circulation from the Last Glacial Maximum. Geophys. Res. Lett. 36, L15603 (2009).

  43. 43.

    Schmittner, A., Green, J. & Wilmes, S.-B. Glacial ocean overturning intensified by tidal mixing in a global circulation model. Geophys. Res. Lett. 42, 4014–4022 (2015).

  44. 44.

    Wunsch, C. & Ferrari, R. Vertical mixing, energy and the general circulation of the oceans. Annu. Rev. Fluid Mech. 36, 281–314 (2004).

  45. 45.

    Marinov, I. et al. Impact of oceanic circulation on biological carbon storage in the ocean and atmospheric pCO2. Glob. Biogeochem. Cycles 22, GB3007 (2008).

  46. 46.

    Mix, A. C. Influence of productivity variations on long-term atmospheric CO2. Nature 337, 541–544 (1989).

  47. 47.

    Kohfeld, K. E., Le Quéré, C., Harrison, S. P. & Anderson, R. F. Role of marine biology in glacial–interglacial CO2 cycles. Science 308, 74–78 (2005).

  48. 48.

    Martnez-Garca, A. et al. Iron fertilization of the subantarctic ocean during the last ice age. Science 343, 1347–1350 (2014).

  49. 49.

    Ödalen, M., Nycander, J., Oliver, K. I., Brodeau, L. & Ridgwell, A. The influence of the ocean circulation state on ocean carbon storage and CO2 drawdown potential in an Earth system model. Biogeosciences 15, 1367–1393 (2018).

  50. 50.

    Marshall, J., Hill, C., Perelman, L. & Adcroft, A. Hydrostatic, quasi-hydrostatic and nonhydrostatic ocean modeling. J. Geophys. Res. Oceans 102, 5733–5752 (1997).

  51. 51.

    Nikurashin, M. & Ferrari, R. Overturning circulation driven by breaking internal waves in the deep ocean. Geophys. Res. Lett. 40, 3133–3137 (2013).

  52. 52.

    Gent, P. R. & McWilliams, J. C. Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr. 20, 150–155 (1990).

  53. 53.

    Redi, M. Oceanic isopycnal mixing by coordinate rotation. J. Phys. Oceanogr. 12, 1154–1158 (1982).

  54. 54.

    Visbeck, M., Marshall, J., Haine, T. & Spall, M. Specification of eddy transfer coefficients in coarse-resolution ocean circulation models. J. Phys. Oceanogr. 27, 381–402 (1997).

  55. 55.

    Losch, M., Menemenlis, D., Campin, J.-M., Heimbach, P. & Hill, C. On the formulation of sea-ice models. Part 1: Effects of different solver implementations and parameterizations. Ocean Model. 33, 129–144 (2010).

  56. 56.

    Follows, M. J., Ito, T. & Dutkiewicz, S. On the solution of the carbonate chemistry system in ocean biogeochemistry models. Ocean Model. 12, 290–301 (2006).

  57. 57.

    Wanninkhof, R. Relationship between wind speed and gas exchange over the ocean. J. Geophys. Res. Oceans 97, 7373–7382 (1992).

  58. 58.

    Krakauer, N. Y., Randerson, J. T., Primeau, F. W., Gruber, N. & Menemenlis, D. Carbon isotope evidence for the latitudinal distribution and wind speed dependence of the air–sea gas transfer velocity. Tellus B Chem. Phys. Meteorol. 58, 390–417 (2006).

  59. 59.

    Wanninkhof, R. Relationship between wind speed and gas exchange over the ocean revisited. Limnol. Oceanogr. Methods 12, 351–362 (2014).

  60. 60.

    Ito, T. & Follows, M. J. Air–sea disequilibrium of carbon dioxide enhances the biological carbon sequestration in the southern ocean. Glob. Biogeochem. Cycles 27, 1129–1138 (2013).

  61. 61.

    Williams, R. G. & Follows, M. J. Ocean Dynamics and the Carbon Cycle: Principles and Mechanisms (Cambridge Univ. Press, 2011).

Download references


This work was funded by the National Science Foundation under awards nos. OCE-1536454 and OCE-1846821, and computational resources were provided by the Research Computing Center at the University of Chicago. A.M. received funding from NERC grant no. NE/P019293/1 (TICTOC).

Author information

A.M. and M.F.J. designed the study. A.M. performed the numerical simulations and analysed the results. A.M. and M.F.J. interpreted the results and wrote the manuscript.

Correspondence to Alice Marzocchi.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Primary Handling Editor(s): James Super, Rachael Rhodes.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary text, Figs. 1–4 and Table 1.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Marzocchi, A., Jansen, M.F. Global cooling linked to increased glacial carbon storage via changes in Antarctic sea ice. Nat. Geosci. (2019) doi:10.1038/s41561-019-0466-8

Download citation