The polar ocean and glacial cycles in atmospheric CO2 concentration

Article metrics


Global climate and the atmospheric partial pressure of carbon dioxide () are correlated over recent glacial cycles, with lower during ice ages, but the causes of the changes are unknown. The modern Southern Ocean releases deeply sequestered CO2 to the atmosphere. Growing evidence suggests that the Southern Ocean CO2 ‘leak’ was stemmed during ice ages, increasing ocean CO2 storage. Such a change would also have made the global ocean more alkaline, driving additional ocean CO2 uptake. This explanation for lower ice-age , if correct, has much to teach us about the controls on current ocean processes.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Records of changing climate, atmospheric CO 2 , and Southern Ocean conditions over the last 800 thousand years.
Figure 5

Figure 2: Symbolic diagram of the ocean’s biological pump.
Figure 3: Summary cartoon of the global ocean today and in two possible ice-age states.
Figure 4: Palaeoclimate records over the most recent full glacial cycle and the last deglaciation, suggesting the roles of the Southern Ocean and North Atlantic in glacial/interglacial atmospheric CO 2 change.


  1. 1

    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)Data on pCO 2atm for the last four glacial cycles are reported and interpreted in the context of other ice core data.

  2. 2

    Sowers, T. & Bender, M. L. Climate records covering the last deglaciation. Science 269, 210–214 (1995)

  3. 3

    Broecker, W. S. Glacial to interglacial changes in ocean chemistry. Prog. Oceanogr. 2, 151–197 (1982)A framework is set forth for considering the causes of glacial/interglacial pCO 2atm change, and the biological pump and its interaction with seafloor calcium carbonate burial are implicated for the first time.

  4. 4

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

  5. 5

    Sarmiento, J. L. & Toggweiler, J. R. A new model for the role of the oceans in determining atmospheric pCO2 . Nature 308, 621–624 (1984)This study and two others6,7 first identified the Southern Ocean as a major leak in the modern biological pump and posited that a reduction in this leak was responsible for lower pCO 2atm during ice ages.

  6. 6

    Siegenthaler, U. & Wenk, T. Rapid atmospheric CO2 variations and ocean circulation. Nature 308, 624–626 (1984)

  7. 7

    Knox, F. & McElroy, M. Changes in atmospheric CO2 influence of the marine biota at high latitude. J. Geophys. Res. 89, 4629–4637 (1984)

  8. 8

    Sigman, D. M. & Haug, G. H. in The Oceans and Marine Geochemistry Vol. 6 Treatise On Geochemistry (ed. Elderfield, H.) 491–528 (Elsevier Pergamon, 2003)

  9. 9

    François, R. F. et al. Water column stratification in the Southern Ocean contributed to the lowering of glacial atmospheric CO2 . Nature 389, 929–935 (1997)Palaeoceanographic evidence is reported that the ice-age Antarctic was characterized by less exchange between the surface and the deep ocean and by an associated increase in the completeness with which Antarctic phytoplankton consumed the available nutrient supply, both of which would have lowered pCO 2atm.

  10. 10

    Toggweiler, J. R. Variations in atmospheric CO2 driven by ventilation of the ocean’s deepest water. Paleoceanography 14, 571–588 (1999)

  11. 11

    Martin, J. H. Glacial-interglacial CO2 change: the iron hypothesis. Paleoceanography 5, 1–13 (1990)

  12. 12

    Stephens, B. B. & Keeling, R. F. The influence of Antarctic sea ice on glacial-interglacial CO2 variations. Nature 404, 171–174 (2000)Reduced CO 2 flux across the sea-to-air interface due to sea-ice cover in the Antarctic is proposed and considered quantitatively as the major driver of lower ice-age pCO 2atm.

  13. 13

    Archer, D., Winguth, A., Lea, D. & Mahowald, N. What caused the glacial/interglacial atmospheric pCO2 cycles? Rev. Geophys. 38, 159–189 (2000)

  14. 14

    Sigman, D. M., McCorkle, D. C. & Martin, W. R. The calcite lysocline as a constraint on glacial/interglacial low-latitude production changes. Glob. Biogeochem. Cycles 12, 409–427 (1998)

  15. 15

    Deutsch, C., Sigman, D. M., Thunell, R. C., Meckler, N. & Haug, G. H. Stable isotope constraints on the glacial/interglacial oceanic nitrogen budget. Glob. Biogeochem. Cycles 18 10.1029/2003GB002189 (2004)

  16. 16

    Ren, H. et al. Foraminiferal isotope evidence of reduced nitrogen fixation in the ice age Atlantic Ocean. Science 323, 244–248 (2009)

  17. 17

    Marchitto, T. M., Lehman, S. J., Ortiz, J. D., Fluckiger, J. & van Geen, A. Marine radiocarbon evidence for the mechanism of deglacial atmospheric CO2 rise. Science 316, 1456–1459 (2007)

  18. 18

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

  19. 19

    Monnin, E. et al. Atmospheric CO2 concentrations over the last glacial termination. Science 291, 112–114 (2001)

  20. 20

    McManus, J. F., François, R., Gherardi, J. M., Keigwin, L. D. & Brown-Leger, S. Collapse and rapid resumption of Atlantic meridional circulation linked to deglacial climate changes. Nature 428, 834–837 (2004)One of a number of important studies showing that ventilation of the deep ocean by the North Atlantic decreased abruptly in response to Heinrich Event 1, coincident with the first major step in Antarctic warming.

  21. 21

    Spero, H. & Lea, D. The cause of carbon isotope minimum events on glacial terminations. Science 296, 522–525 (2002)

  22. 22

    Barker, S. et al. Interhemispheric Atlantic seesaw response during the last deglaciation. Nature 457, 1097–1050 (2009)

  23. 23

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

  24. 24

    Toggweiler, J. R., Murnane, R., Carson, S., Gnanadesikan, A. & Sarmiento, J. L. Representation of the carbon cycle in box models and GCMs: 2. Organic pump. Glob. Biogeochem. Cycles 17 1027 10.1029/2001GB001841 (2003)

  25. 25

    Archer, D. E. et al. Model sensitivity in the effect of Antarctic sea ice and stratification on atmospheric pCO2 . Paleoceanography 18 1012 10.1029/2002pa000760 (2003)

  26. 26

    Marinov, I., Gnanadesikan, A., Toggweiler, J. R. & Sarmiento, J. L. The Southern Ocean biogeochemical divide. Nature 441, 964–967 (2006)

  27. 27

    Orsi, A. H., Smethie, W. M. & Bullister, J. L. On the total input of Antarctic waters to the deep ocean: a preliminary estimate from chlorofluorocarbon measurements. J. Geophys. Res. 107 17 10.1029/2001jc000976 (2002)

  28. 28

    Mortlock, R. A. et al. Evidence for lower productivity in the Antarctic during the last glaciation. Nature 351, 220–223 (1991)In this first large-scale reconstruction of Southern Ocean productivity during the last ice age, the Antarctic was found to be less productive than today, but the Subantarctic was found to be more productive.

  29. 29

    Abelmann, A., Gersonde, R., Cortese, G., Kuhn, G. & Smetacek, V. Extensive phytoplankton blooms in the Atlantic sector of the glacial Southern Ocean. Paleoceanography 21 PA1013 10.1029/2005PA001199 (2006)

  30. 30

    Robinson, R. S. & Sigman, D. M. Nitrogen isotopic evidence for a poleward decrease in surface nitrate within the ice age Antarctic. Quat. Sci. Rev. 27, 1076–1090 (2008)

  31. 31

    Sikes, E. L., Samson, C. R., Guilderson, T. P. & Howard, W. R. Old radiocarbon ages in the southwest Pacific Ocean during the last glacial period and deglaciation. Nature 405, 555–559 (2000)

  32. 32

    Galbraith, E. D. et al. Carbon dioxide release from the North Pacific abyss during the last deglaciation. Nature 449, 890–893 (2007)

  33. 33

    Keigwin, L. D. Radiocarbon and stable isotope constraints on Last Glacial Maximum and Younger Dryas ventilation in the western North Atlantic. Paleoceanography 19 PA4012 10.1029/2004PA001029 (2004)

  34. 34

    Hughen, K. et al. 14C activity and global carbon cycle changes over the past 50,000 years. Science 303, 202–207 (2004)

  35. 35

    Schmittner, A. Southern Ocean sea ice and radiocarbon ages of glacial bottom waters. Earth Planet. Sci. Lett. 213, 53–62 (2003)

  36. 36

    Jaccard, S. L. et al. Subarctic Pacific evidence for a glacial deepening of the oceanic respired carbon pool. Earth Planet. Sci. Lett. 277, 156–165 (2009)

  37. 37

    Keir, R. S. On the late Pleistocene ocean geochemistry and circulation. Paleoceanography 3, 413–445 (1988)

  38. 38

    Boyle, E. A. Vertical oceanic nutrient fractionation and glacial/interglacial CO2 cycles. Nature 331, 55–56 (1988)Motivated by his palaeoceanographic data, this author recognized that (1) shifting regenerated nutrients and CO 2 from the mid-depth to abyssal ocean would drive a deep sea CaCO 3 dissolution event, helping to lower pCO 2atm, and (2) accumulation of regenerated products in the abyssal (rather than mid-depth) ocean renders moot previous concerns regarding the lack of ice-age evidence for ocean suboxia.

  39. 39

    Peacock, S., Lane, E. & Restrepo, J. M. A possible sequence of events for the generalized glacial-interglacial cycle. Glob. Biogeochem. Cycles 20 GB2010 10.1029/2005GB002448 (2006)

  40. 40

    Kumar, N. et al. Increased biological productivity and export production in the glacial Southern Ocean. Nature 378, 675–680 (1995)

  41. 41

    Martinez-Garcia, A. et al. Links between iron supply, marine productivity, sea surface temperature, and CO2 over the last 1.1 Ma. Paleoceanography 24 14 10.1029/2008pa001657 (2009)

  42. 42

    Robinson, R. S. et al. Diatom-bound 15N/14N: new support for enhanced nutrient consumption in the ice age subantarctic. Paleoceanography 20 PA3003 10.1029/2004PA001114 (2005)

  43. 43

    Brzezinski, M. A. et al. A switch from Si(OH)4 to NO3 depletion in the glacial Southern Ocean. Geophys. Res. Lett. 29 12 10.1029/2001GL014349 (2002)

  44. 44

    Loubere, P., Mekik, F., François, R. & Pichat, S. Export fluxes of calcite in the eastern equatorial Pacific from the Last Glacial Maximum to present. Paleoceanography 19 PA2018 10.1029/2003PA000986 (2004)

  45. 45

    Matsumoto, K., Sarmiento, J. L. & Brzezinski, M. A. Silicic acid ‘leakage’ from the Southern Ocean as a possible mechanism for explaining glacial atmospheric pCO2 . Glob. Biogeochem. Cycles 16 10.1029/2001GB001442 (2002)

  46. 46

    Watson, A. J., Bakker, D. C. E., Ridgewell, A. J., Boyd, P. W. & Law, C. S. Effect of iron supply on Southern Ocean CO2 uptake and implications for atmospheric CO2 . Nature 407, 730–733 (2000)

  47. 47

    Lynch-Stieglitz, J. et al. Atlantic meridional overturning circulation during the Last Glacial Maximum. Science 316, 66–69 (2007)A literature review and an attempt at community consensus as to the nature of North Atlantic deep ocean circulation during the last ice age.

  48. 48

    Liu, Z. Y., Shin, S. I., Webb, R. S., Lewis, W. & Otto-Bliesner, B. L. Atmospheric CO2 forcing on glacial thermohaline circulation and climate. Geophys. Res. Lett. 32 4 10.1029/2004gl021929 (2005)

  49. 49

    Manabe, S. & Stouffer, R. J. Century-scale effects of increased atmospheric CO2 on the ocean-atmosphere system. Nature 364, 215–218 (1993)

  50. 50

    Toggweiler, J. R., Russell, J. L. & Carson, S. R. Midlatitude westerlies, atmospheric CO2, and climate change during the ice ages. Paleoceanography 21 PA2005 10.1029/2005PA001154 (2006)Changes in the Southern Hemisphere westerly winds are proposed as the driver of reduced Antarctic overturning during ice ages.

  51. 51

    de Boer, A. M., Toggweiler, J. R. & Sigman, D. M. Atlantic dominance of the meridional overturning circulation. J. Phys. Oceanogr. 38 435–450 10.1175/2007jp03731.1 (2008)

  52. 52

    Sigman, D. M., Jaccard, S. L. & Haug, G. H. Polar ocean stratification in a cold climate. Nature 428, 59–63 (2004)

  53. 53

    de Boer, A. M., Sigman, D. M., Toggweiler, J. R. & Russell, J. L. Effect of global ocean temperature change on deep ocean ventilation. Paleoceanography 22 PA2210 10.1029/2005pa001242 (2007)

  54. 54

    Gildor, H. & Tziperman, E. Physical mechanisms behind biogeochemical glacial-interglacial CO2 variations. Geophys. Res. Lett. 28, 2421–2424 (2001)

  55. 55

    Keeling, R. F. & Visbeck, M. Palaeoceanography: Antarctic stratification and glacial CO2 . Nature 412, 605–606 (2001)

  56. 56

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

  57. 57

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

  58. 58

    Paillard, D. & Parrenin, F. The Antarctic ice sheet and the triggering of deglaciations. Earth Planet. Sci. Lett. 227, 263–271 (2004)

  59. 59

    Broecker, W. S. Paleocean circulation during the last deglaciation: A bipolar seesaw? Paleoceanography 13, 119–121 (1998)

  60. 60

    Kuhlbrodt, T. et al. On the driving processes of the Atlantic meridional overturning circulation. Rev. Geophys. 45 10.1029/2004rg000166 (2007)

  61. 61

    Toggweiler, J. R. & Samuels, B. Effect of Drake Passage on the global thermohaline circulation. Deep Sea Res. I 42, 477–500 (1995)

  62. 62

    Munk, W. H. & Wunsch, C. Abyssal recipes II: energetics of tidal and wind mixing. Deep Sea Res. I 45, 1977–2010 (1998)

  63. 63

    Huang, R. X. Mixing and energetics of the oceanic thermohaline circulation. J. Phys. Oceanogr. 29, 727–746 (1999)

  64. 64

    Bouttes, N., Roche, D. M. & Paillard, D. Impact of strong deep ocean stratification on the glacial carbon cycle. Paleoceanography 24 PA3203 10.1029/2008pa001707 (2009)

  65. 65

    Hodell, D. A. & Venz-Curtis, K. A. Late Neogene history of deepwater ventilation in the Southern Ocean. Geochem. Geophys. Geosyst. 7 Q09001 10.1029/2005GC001211 (2006)

  66. 66

    Hodell, D. A., Venz, K. A., Charles, C. D. & Ninnemann, U. S. Pleistocene vertical carbon isotope and carbonate gradients in the South Atlantic sector of the Southern Ocean. Geochem. Geophys. Geosyst. 4 1004 10.1029/2002gc000367 (2003)

  67. 67

    Takahashi, T. et al. Climatological mean and decadal change in surface ocean pCO2, and net sea-air CO2 flux over the global oceans. Deep Sea Res. II 56, 554–577 (2009)

  68. 68

    Maqueda, M. A. M. & Rahmstorf, S. Did Antarctic sea-ice expansion cause glacial CO2 decline? Geophys. Res. Lett. 29 3 10.1029/2001gl013240 (2002)

  69. 69

    Mitchell, B. G., Brody, E. A., Holm-Hansen, O., McClain, C. & Bishop, J. Light limitation of phytoplankton biomass and macronutrient utilization in the Southern Ocean. Limnol. Oceanogr. 36, 1662–1677 (1991)

  70. 70

    Martin, J. H., Fitzwater, S. E. & Gordon, R. M. Iron deficiency limits growth in Antarctic waters. Glob. Biogeochem. Cycles 4, 5–12 (1990)

  71. 71

    Lefèvre, N. & Watson, A. J. Modeling the geochemical cycle of iron in the oceans and its impact on atmospheric CO2 concentrations. Glob. Biogeochem. Cycles 13, 727–736 (1999)

  72. 72

    Gersonde, R., Crosta, X., Abelmann, A. & Armand, L. Sea-surface temperature and sea lee 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)

  73. 73

    Mahowald, N. et al. Dust sources and deposition during the last glacial maximum and current climate: a comparison of model results with paleodata from ice cores and marine sediments. J. Geophys. Res. 104, 15895–15916 (1999)

  74. 74

    Sigman, D. M., de Boer, A. M. & Haug, G. H. in Past and Future Changes of the Oceanic Meridional Overturning Circulation: Mechanisms and Impacts (eds Schmittner, A., Chiang, J. H. C. & Hemming, S. R.) Geophysical Monograph 173, 335–350 (American Geophysical Union, 2007)

  75. 75

    Hemming, S. R. Heinrich events: massive late Pleistocene detritus layers of the North Atlantic and their global climate imprint. Rev. Geophys. 42 2003RG1005 10.1029/2003RG000128 (2004)

  76. 76

    Huybers, P. & Denton, G. Antarctic temperature at orbital timescales controlled by local summer duration. Nature Geosci. 1, 787–792 (2008)

  77. 77

    Timmermann, A., Timm, O., Stott, L. & Menviel, L. The roles of CO2 and orbital forcing in driving Southern Hemispheric temperature variations during the last 21000 yr. J. Clim. 22, 1626–1640 (2009)

  78. 78

    Ahn, J. & Brook, E. J. Atmospheric CO2 and climate on millennial time scales during the last glacial period. Science 322, 83–85 (2008)

  79. 79

    Schmittner, A., Brook, E. & Ahn, J. in Past and Future Changes of the Oceanic Meridional Overturning Circulation: Mechanisms and Impacts (eds Schmittner, A., Chiang, J. H. C. & Hemming, S. R.) Geophysical Monograph 173, 315–334 (American Geophysical Union, 2007)

  80. 80

    Cheng, H. et al. Ice Age terminations. Science 326, 248–252 (2009)

  81. 81

    Venz, K. A., Hodell, D. A., Stanton, C. & Warnke, D. A. A 1.0 Myr record of glacial North Atlantic intermediate water variability from ODP site 982 in the northeast Atlantic. Paleoceanography 14, 42–52 (1999)

  82. 82

    Crowley, T. J. North Atlantic Deep Water cools the Southern Hemisphere. Paleoceanography 7, 489–497 (1992)

  83. 83

    Lamy, F. et al. Modulation of the bipolar seesaw in the southeast Pacific during Termination 1. Earth Planet. Sci. Lett. 259, 400–413 (2007)

  84. 84

    Toggweiler, J. R. Shifting westerlies. Science 323, 1434–1435 (2009)

  85. 85

    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)

  86. 86

    Cutler, K. B. et al. Rapid sea-level fall and deep-ocean temperature change since the last interglacial period. Earth Planet. Sci. Lett. 206, 253–271 (2003)

  87. 87

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

  88. 88

    Haug, G. H. & Sigman, D. M. Palaeoceanography: polar twins. Nature Geosci. 2, 91–92 (2009)

  89. 89

    Jaccard, S. L. et al. Glacial/interglacial changes in subarctic North Pacific stratification. Science 308, 1003–1006 (2005)

  90. 90

    Brunelle, B. G. et al. Evidence from diatom-bound nitrogen isotopes for subarctic Pacific stratification during the last ice age and a link to North Pacific denitrification changes. Paleoceanography 22 PA1215 10.1029/2005PA001205 (2007)

  91. 91

    Galbraith, E. D. et al. Consistent relationship between global climate and surface nitrate utilization in the western subarctic Pacific throughout the last 500 ka. Paleoceanography 23 PA2212 10.1029/2007PA001518 (2008)

  92. 92

    Lisiecki, L. E. & Raymo, M. E. A. Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography 20 PA1003 10.1029/2004pa001071 (2005)

  93. 93

    Luthi, D. et al. High-resolution carbon dioxide concentration record 650,000–800,000 years before present. Nature 453, 379–382 (2008)

  94. 94

    Jouzel, J. et al. Orbital and millennial Antarctic climate variability over the past 800,000 years. Science 317, 793–796 (2007)

  95. 95

    Hodell, D. A., Gersonde, R. & Blum, P. Leg 177 synthesis: insights into Southern Ocean paleoceanography on tectonic to millennial timescales. Proc. ODP Sci. Res. 177 1–54 10.2973/ (2002)

  96. 96

    Berger, A. & Loutre, M. F. Insolation values for the climate of the last 10 million years. Quat. Sci. Rev. 10, 297–317 (1991)

  97. 97

    Siegenthaler, U. et al. Stable carbon cycle-climate relationship during the late Pleistocene. Science 310, 1313–1317 (2005)

  98. 98

    EPICA community members. Eight glacial cycles from an Antarctic ice core. Nature 429, 623–628 (2004)

  99. 99

    Grootes, P. M. & Stuiver, M. Oxygen 18/16 variability in Greenland snow and ice with 103 to 105-year time resolution. J. Geophys. Res. 102, 26455–26470 (1997)

Download references


We thank J. F. Adkins, R. F. Anderson, and J. Lynch-Stieglitz for discussions. Support was provided by the US NSF, the German DFG, the Humboldt and MacArthur Foundations, the Siebel Energy Grand Challenge at Princeton, and O. Happel.

Author information

D.M.S. and G.H.H. determined the content of the review. M.P.H. contributed throughout but especially to the treatment of geochemistry. Text and figure production was shared, led by D.M.S.

Correspondence to Daniel M. Sigman.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Sigman, D., Hain, M. & Haug, G. The polar ocean and glacial cycles in atmospheric CO2 concentration. Nature 466, 47–55 (2010) doi:10.1038/nature09149

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.