Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Southern Ocean carbon sink enhanced by sea-ice feedbacks at the Antarctic Cold Reversal


The Southern Ocean occupies 14% of the Earth’s surface and plays a fundamental role in the global carbon cycle and climate. It provides a direct connection to the deep ocean carbon reservoir through biogeochemical processes that include surface primary productivity, remineralization at depth and the upwelling of carbon-rich water masses. However, the role of these different processes in modulating past and future air–sea carbon flux remains poorly understood. A key period in this regard is the Antarctic Cold Reversal (ACR, 14.6–12.7 kyr bp), when mid- to high-latitude Southern Hemisphere cooling coincided with a sustained plateau in the global deglacial increase in atmospheric CO2. Here we reconstruct high-latitude Southern Ocean surface productivity from marine-derived aerosols captured in a highly resolved horizontal ice core. Our multiproxy reconstruction reveals a sustained signal of enhanced marine productivity across the ACR. Transient climate modelling indicates this period coincided with maximum seasonal variability in sea-ice extent, implying that sea-ice biological feedbacks enhanced CO2 sequestration and created a substantial regional marine carbon sink, which contributed to the plateau in CO2 during the ACR. Our results highlight the role Antarctic sea ice plays in controlling global CO2, and demonstrate the need to incorporate such feedbacks into climate–carbon models.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Intercomparison of Antarctic ice core with marine proxy records from independent referenced studies.
Fig. 2: The South Atlantic sector of the Southern Ocean with the locations of the Patriot Hills in the Ellsworth Mountains, the EDML ice core and marine cores MD07-313421 and TN057-134.
Fig. 3: Stratigraphic and chronological details of the Patriot Hill BIA.
Fig. 4: Marine biomarkers from Patriot Hills BIA.
Fig. 5: Regional climate proxy and model intercomparisons with the Patriot Hills record.
Fig. 6: Schematic depicting events across mid- to high-latitude Southern Ocean during the LGT.

Data availability

The data supporting this study is available at National Oceanic and Atmospheric Administration Paleoclimatology Database ( The data from core MD07-3134 are available on the PANGEA Database at and Source data for Figs. 1, 4 and 5 and Extended Data Fig. 1 are available with the paper.


  1. 1.

    Bauska, T. K. et al. Carbon isotopes characterize rapid changes in atmospheric carbon dioxide during the last deglaciation. Proc. Natl Acad. Sci. USA 113, 3465–3470 (2016).

    Google Scholar 

  2. 2.

    Bauska, T. K. et al. Controls on millennial‐scale atmospheric CO2 variability during the last glacial period. Geophys. Res. Lett. 45, 7731–7740 (2018).

    Google Scholar 

  3. 3.

    Monnin, E. et al. Atmospheric CO2 concentrations over the Last Glacial Termination. Science 291, 112–114 (2001).

    Google Scholar 

  4. 4.

    Anderson, R. F. et al. Wind-driven upwelling in the Southern Ocean and the deglacial rise in atmospheric CO2. Science 323, 1443–1448 (2009).

    Google Scholar 

  5. 5.

    Gottschalk, J. et al. Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes. Nat. Commun. 7, 11539 (2016).

    Google Scholar 

  6. 6.

    Toggweiler, J. R., Russell, J. L. & Carson, S. R. Midlatitude westerlies, atmospheric CO2, and climate change during the ice ages. Paleoceanography 21, PA2005 (2006).

    Google Scholar 

  7. 7.

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

    Google Scholar 

  8. 8.

    Huang, H., Gutjahr, M., Eisenhauer, A. & Kuhn, G. No detectable Weddell Sea Antarctic Bottom Water export during the Last and Penultimate Glacial Maximum. Nat. Commun. 11, 14302 (2020).

    Google Scholar 

  9. 9.

    Jaccard, S. L., Galbraith, E. D., Martínez-García, A. & Anderson, R. F. Covariation of deep Southern Ocean oxygenation and atmospheric CO2 through the last ice age. Nature 530, 207–210 (2016).

    Google Scholar 

  10. 10.

    Martínez-García, A. et al. Iron fertilization of the Subantarctic ocean during the last ice age. Science 343, 1347–1350 (2014).

    Google Scholar 

  11. 11.

    Jaccard, S. L. et al. Two modes of change in Southern Ocean productivity over the past million years. Science 339, 1419–1423 (2013).

    Google Scholar 

  12. 12.

    Butterworth, B. J. & Miller, S. D. Air–sea exchange of carbon dioxide in the Southern Ocean and Antarctic marginal ice zone. Geophys. Res. Lett. 43, 7223–7230 (2016).

    Google Scholar 

  13. 13.

    Delille, B. et al. Southern Ocean CO2 sink: the contribution of the sea ice. J. Geophys. Res. Oceans 119, 6340–6355 (2014).

    Google Scholar 

  14. 14.

    Barnes, D.K. Antarctic sea ice losses drive gains in benthic carbon drawdown. Curr. Biol. 25, R789 (2015).

    Google Scholar 

  15. 15.

    Boyd, P. W., Claustre, H., Levy, M., Siegel, D. A. & Weber, T. Multi-faceted particle pumps drive carbon sequestration in the ocean. Nature 568, 327–335 (2019).

    Google Scholar 

  16. 16.

    Boyd, P. W. et al. A mesoscale phytoplankton bloom in the polar Southern Ocean stimulated by iron fertilization. Nature 407, 695–702 (2000).

    Google Scholar 

  17. 17.

    Marcott, S. A. et al. Centennial-scale changes in the global carbon cycle during the last deglaciation. Nature 514, 616–619 (2014).

    Google Scholar 

  18. 18.

    Fogwill, C. J. & Kubik, P. W. A glacial stage spanning the Antarctic Cold Reversal in Torres del Paine (51°S), Chile, based on preliminary cosmogenic exposure ages. Geogr. Ann. Ser. A 87A, 403–408 (2005).

    Google Scholar 

  19. 19.

    Pedro, J. B. et al. The spatial extent and dynamics of the Antarctic Cold Reversal. Nat. Geosci. 9, 51–55 (2015).

    Google Scholar 

  20. 20.

    McGlone, M. S., Turney, C. S. M., Wilmshurst, J. M., Renwick, J. & Pahnke, K. Divergent trends in land and ocean temperature in the Southern Ocean over the past 18,000 years. Nat. Geosci. 3, 622–626 (2010).

    Google Scholar 

  21. 21.

    Weber, M. E. et al. Millennial-scale variability in Antarctic ice-sheet discharge during the last deglaciation. Nature 510, 134–138 (2014).

    Google Scholar 

  22. 22.

    Fogwill, C. et al. Antarctic ice sheet discharge driven by atmosphere–ocean feedbacks at the Last Glacial Termination. Sci. Rep. 7, 39979 (2017).

    Google Scholar 

  23. 23.

    Schmitt, J. et al. Carbon isotope constraints on the deglacial CO2 rise from ice cores. Science 336, 711–714 (2012).

    Google Scholar 

  24. 24.

    Sprenk, D. et al. Southern Ocean bioproductivity during the last glacial cycle—new decadal-scale insight from the Scotia Sea. Geol. Soc. Spec. Publ. 381, 245–261 (2013).

    Google Scholar 

  25. 25.

    Meyer-Jacob, C. et al. Independent measurement of biogenic silica in sediments by FTIR spectroscopy and PLS regression. J. Paleolimnol. 52, 245–255 (2014).

    Google Scholar 

  26. 26.

    Turney, C. S. M. et al. Late Pleistocene and early Holocene change in the Weddell Sea: a new climate record from the Patriot Hills, Ellsworth Mountains, West Antarctica. J. Quat. Sci. 28, 697–704 (2013).

    Google Scholar 

  27. 27.

    Tetzner, D., Thomas, E. & Allen, C.A. Validation of ERA5 reanalysis data in the Southern Antarctic Peninsula—Ellsworth Land region, and its implications for ice core studies. Geosciences 9, 289 (2019).

  28. 28.

    Turney, C. S. M. et al. Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica. Proc. Natl Acad. Sci. USA 117, 3996–4006 (2020).

    Google Scholar 

  29. 29.

    Winter, K. et al. Assessing the continuity of the blue ice climate record at Patriot Hills, Horseshoe Valley, West Antarctica. Geophys. Res. Lett. 43, 2019–2026 (2016).

    Google Scholar 

  30. 30.

    Huber, S. A., Balz, A., Abert, M. & Pronk, W. Characterisation of aquatic humic and non-humic matter with size-exclusion chromatography – organic carbon detection – organic nitrogen detection (LC-OCD-OND). Water Res. 45, 879–885 (2011).

    Google Scholar 

  31. 31.

    Jørgensen, L. et al. Global trends in the fluorescence characteristics and distribution of marine dissolved organic matter. Mar. Chem. 126, 139–148 (2011).

    Google Scholar 

  32. 32.

    D’Andrilli, J., Foreman, C. M., Sigl, M., Priscu, J. C. & McConnell, J. R. A 21,000 year record of organic matter quality in the WAIS Divide ice core. Clim. Discuss. 2016, 1–15 (2016).

    Google Scholar 

  33. 33.

    Smith, H. J. et al. Microbial formation of labile organic carbon in Antarctic glacial environments. Nat. Geosci. 10, 356–359 (2017).

    Google Scholar 

  34. 34.

    Rohde, R. A., Price, P. B., Bay, R. C. & Bramall, N. E. In situ microbial metabolism as a cause of gas anomalies in ice. Proc. Natl Acad. Sci. USA 105, 8667–8672 (2008).

    Google Scholar 

  35. 35.

    Price, P. & Bay, R. Marine bacteria in deep Arctic and Antarctic ice cores: a proxy for evolution in oceans over 300 million generations. Biogeosciences 9, 3799–3815 (2012).

    Google Scholar 

  36. 36.

    Moorthi, S., Caron, D., Gast, R. & Sanders, R. Mixotrophy: a widespread and important ecological strategy for planktonic and sea-ice nanoflagellates in the Ross Sea, Antarctica. Aquat. Micro. Ecol. 54, 269–277 (2009).

    Google Scholar 

  37. 37.

    Massana, R. Eukaryotic picoplankton in surface oceans. Annu. Rev. Microbiol. 65, 91–110 (2011).

    Google Scholar 

  38. 38.

    Rodionov, S.N. A sequential algorithm for testing climate regime shifts. Geophys. Res. Lett. 31, L09204 (2004).

    Google Scholar 

  39. 39.

    Wolff, E. W. et al. Southern Ocean sea-ice extent, productivity and iron flux over the past eight glacial cycles. Nature 440, 491–496 (2006).

    Google Scholar 

  40. 40.

    Abelmann, A. et al. The seasonal sea-ice zone in the glacial Southern Ocean as a carbon sink. Nat. Commun. 6, 8136 (2015).

    Google Scholar 

  41. 41.

    Esper, O. & Gersonde, R. New tools for the reconstruction of Pleistocene Antarctic sea ice. Palaeogeogr. Palaeoclimatol. Palaeoecol. 399, 260–283 (2014).

    Google Scholar 

  42. 42.

    Menviel, L., Timmermann, A., Elison Timm, O. & Mouchet, A. Deconstructing the Last Glacial Termination: the role of millennial and orbital-scale forcings. Quat. Sci. Rev. 30, 1155–1172 (2011).

    Google Scholar 

  43. 43.

    Collins, L. G., Pike, J., Allen, C. S. & Hodgson, D. A. High-resolution reconstruction of southwest Atlantic sea-ice and its role in the carbon cycle during marine isotope stages 3 and 2. Paleoceanography 27, PA3217 (2012).

    Google Scholar 

  44. 44.

    Duprat, L. P. A. M., Bigg, G. R. & Wilton, D. J. Enhanced Southern Ocean marine productivity due to fertilization by giant icebergs. Nat. Geosci. 9, 219–221 (2016).

    Google Scholar 

  45. 45.

    Fogwill, C. J., Phipps, S. J., Turney, C. S. M. & Golledge, N. R. Sensitivity of the Southern Ocean to enhanced regional Antarctic ice sheet meltwater input. Earth Future 3, 317–329 (2015).

    Google Scholar 

  46. 46.

    Golledge, N. R. et al. Antarctic contribution to meltwater pulse 1A from reduced Southern Ocean overturning. Nat. Commun. 5, 6107 (2014).

    Google Scholar 

  47. 47.

    Menviel, L., Timmermann, A., Timm, O. E. & Mouchet, A. Climate and biogeochemical response to a rapid melting of the West Antarctic Ice Sheet during interglacials and implications for future climate. Paleoceanography 25, PA4231 (2010).

    Google Scholar 

  48. 48.

    Hogg, A. Punctuated shutdown of Atlantic Meridional Overturning Circulation during the Greenland Stadial 1. Sci. Rep. 6, 25902 (2016).

    Google Scholar 

  49. 49.

    Menviel, L. et al. Southern Hemisphere westerlies as a driver of the early deglacial atmospheric CO2 rise. Nat. Commun. 9, 2503 (2018).

    Google Scholar 

  50. 50.

    Parkinson, C. L. A 40-y record reveals gradual Antarctic sea ice increases followed by decreases at rates far exceeding the rates seen in the Arctic. Proc. Natl Acad. Sci. USA 116, 14414–14423 (2019).

    Google Scholar 

  51. 51.

    WAIS Divide Members Precise interpolar phasing of abrupt climate change during the last ice age. Nature 520, 661–665 (2015).

  52. 52.

    Wolff, E. et al. Southern Ocean sea-ice extent, productivity and iron flux over the past eight glacial cycles. Nature 440, 491–496 (2006).

    Google Scholar 

  53. 53.

    Orsi, A. H., Whitworth, T. III & Nowlin, W. D. Jr. On the meridional extent and fronts of the Antarctic Circumpolar Current. Deep Sea Res. Pt 1 42, 641–673 (1995).

    Google Scholar 

  54. 54.

    Stein, A. et al. NOAA’s HYSPLIT atmospheric transport and dispersion modeling system. Bull. Am. Meteorol. Soc. 96, 2059–2077 (2015).

    Google Scholar 

  55. 55.

    Wessel, P. et al. New, improved version of Generic Mapping Tools released. Eos 79, 579–579 (1998).

    Google Scholar 

  56. 56.

    Iannone, R. Splitr: Use the HYSPLIT model from inside R. R package version (2019).

  57. 57.

    Carslaw, D. C. & Ropkins, K. Openair—an R package for air quality data analysis. Environ. Model. Softw. 27–28, 52–61 (2012).

    Google Scholar 

  58. 58.

    Reijmer, C. H., Greuell, W. & Oerlemans, J. The annual cycle of meteorological variables and the surface energy balance on Berkner Island, Antarctica. Ann. Glaciol. 29, 49–54 (1999).

    Google Scholar 

  59. 59.

    Abram, N. J., Mulvaney, R., Wolff, E. W. & Mudelsee, M. Ice core records as sea ice proxies: an evaluation from the Weddell Sea region of Antarctica. J. Geophys. Res. 112, D15101 (2007).

    Google Scholar 

  60. 60.

    Fox, B., Thorn, R., Anesio, A. & Reynolds, D. M. The in situ bacterial production of fluorescent organic matter; an investigation at a species level. Water Res. 125, 350–359 (2017).

    Google Scholar 

  61. 61.

    Tuner, C. R., Miller, D. J., Coyne, K. J. & Corush, J. Improved methods for capture, extraction, and quantitative assay of environmental DNA from Asian bigheaded carp (Hypophthalmichthys spp.). PLoS ONE 9, e114329 (2014).

    Google Scholar 

  62. 62.

    Adler, C. J. et al. Sequencing ancient calcified dental plaque shows changes in oral microbiota with dietary shifts of the Neolithic and Industrial revolutions. Nat. Genet. 45, 450–455 (2013).

    Google Scholar 

  63. 63.

    Caporaso, J. G. Ultra-high-throughput microbial community analysis on the Illumina HiSeq and MiSeq platforms. ISME J. 6, 1621–1624 (2012).

    Google Scholar 

  64. 64.

    Caporaso, J. G. QIIME allows analysis of high-throughput community sequencing data. Nat. Methods 7, 335–336 (2010).

    Google Scholar 

  65. 65.

    DeSantis, T. Z. et al. Greengenes, a chimera-checked 16S rRNA gene database and workbench compatible with ARB. Appl. Environ. Microbiol. 72, 5069–5072 (2006).

    Google Scholar 

  66. 66.

    Salter, S. J. et al. Reagent and laboratory contamination can critically impact sequence-based microbiome analyses. BMC Biol. 12, 87 (2014).

    Google Scholar 

  67. 67.

    Chen, T. et al. The Human Oral Microbiome Database: a web accessible resource for investigating oral microbe taxonomic and genomic information. Database 2010, baq013 (2010).

    Google Scholar 

  68. 68.

    Sunagawa, S. et al. Structure and function of the global ocean microbiome. Science 348, 1261359 (2015).

    Google Scholar 

Download references


C.J.F., C.S.M.T., L.M., N.R.G., L.S.W. and A.C. are supported by their respective Australian Research Council (ARC) and Royal Society of NZ fellowships, and C.J.F. and A.G.C. thank Keele University for a Research Development Award that underpinned this research at Keele University IceLab and Exeter University. Fieldwork was undertaken under ARC Linkage Project (LP120200724), supported by Linkage Partner Antarctic Logistics and Expeditions, whose enduring support we acknowledge. CSIRO’s contribution was supported in part by the Australian Climate Change Science Program (ACCSP), an Australian Government Initiative. S.D. acknowledges financial support from Coleg Cymraeg Cenedlaethol and the European Research Council (ERC grant agreement no. 25923). M.E.W. acknowledges support from the Deutsche Forschungsgemeinschaft (grant no. We2039/8-1). Finally, we thank H. Glanville for comments on the final draft of the manuscript, and A. Jeffery for advice on SEM analysis.

Author information




C.J.F., C.S.M.T., A.B. and A.C. conceived this research. C.J.F., C.S.M.T., A.B., M.E.W., D.E., M.R., D.P.T., T.D.vO., A.D.M., M.A.J.C., S.D., M.I.B., N.C.M., J.V., A.R., L.M., H.M., CM, J.Y., M.M., A.G.C., M.R.P.H., A.P., J.L. and L.S.W. undertook analysis and sampling. C.J.F., C.S.M.T., A.B., M.E.W., M.R.P.H. and A.C. wrote the manuscript with input from all the authors.

Corresponding author

Correspondence to C. J. Fogwill.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Primary Handling Editor: James Super.

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

Extended data

Extended Data Fig. 1 Reproducibility of fOM signal.

Reproducibility of fOM signal. 5 m resolved fOM concentration (Component 1; TRYLIS in red), plotted against data from a second parallel transect from the Patriot Hills transect (~3 m resolved black dashed line). The dashed lines represent replicate samples from the same transect which were taken in 2014/15 and measured in 2015 at UNSW Icelab (black dots), and subsequently reanalysed in 2019 at Keele Icelab (red triangles). The records are synchronised from water stable isotopes, site survey data and DGPS, and taken within 4 m of one another from a parallel transect (inset).

Source data

Supplementary information

Supplementary Information

Supplementary Sections 1–9, Figs. 1–7 and Tables 1–3.

Source data

Source Data Fig. 1

Numerical data used to generate graphs in the figure.

Source Data Fig. 4

Numerical data used to generate graphs in the figure.

Source Data Fig. 5

Numerical data used to generate graphs in the figure.

Source Data Extended Data Fig. 1

Numerical data used to generate graphs in the figure.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Fogwill, C.J., Turney, C.S.M., Menviel, L. et al. Southern Ocean carbon sink enhanced by sea-ice feedbacks at the Antarctic Cold Reversal. Nat. Geosci. 13, 489–497 (2020).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing