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Glacial/interglacial variations in atmospheric carbon dioxide


Twenty years ago, measurements on ice cores showed that the concentration of carbon dioxide in the atmosphere was lower during ice ages than it is today. As yet, there is no broadly accepted explanation for this difference. Current investigations focus on the ocean's ‘biological pump’, the sequestration of carbon in the ocean interior by the rain of organic carbon out of the surface ocean, and its effect on the burial of calcium carbonate in marine sediments. Some researchers surmise that the whole-ocean reservoir of algal nutrients was larger during glacial times, strengthening the biological pump at low latitudes, where these nutrients are currently limiting. Others propose that the biological pump was more efficient during glacial times because of more complete utilization of nutrients at high latitudes, where much of the nutrient supply currently goes unused. We present a version of the latter hypothesis that focuses on the open ocean surrounding Antarctica, involving both the biology and physics of that region.

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Figure 1: The history of atmospheric CO2 back to 420 kyr ago as recorded by the gas content in the Vostok ice core from Antarctica4.
Figure 2: A simplified view of the Holocene (pre-industrial) carbon cycle.
Figure 3: The p CO 2 of surface sea water at 20 °C and a salinity of 35 parts per thousand, as set by its dissolved inorganic carbon (DIC) content and alkalinity (ALK).
Figure 4: The time-dependent response of the CYCLOPS model to a sudden halving in the CaCO3/Corg ratio of the export flux out of the low-latitude surface ocean33.
Figure 5: The effect on atmospheric CO2 of the biological pump in a region of deep-ocean ventilation.
Figure 6: The modern ocean (a, b) and a Southern Ocean-based hypothesis for reduced levels of atmospheric CO2 during glacial times ( c, d).


  1. 1

    Hays, J. D., Imbrie, J. & Shackleton, N. J. Variations in the Earth's orbit: Pacemaker of the Ice Ages. Science 194, 1121– 1132 (1976).

    ADS  CAS  PubMed  Google Scholar 

  2. 2

    Berger, A., Imbrie, J., Hays, J., Kukla, G. & Saltzman, B. (eds) Milankovitch and Climate (Reidel, Boston, 1984).

    Google Scholar 

  3. 3

    Barnola, J. M., Raynaud, D., Korotkevich, Y. S. & Lorius, C. Vostok ice core provides 160,000-year record of atmospheric CO2. Nature 329, 408–414 (1987).

    ADS  CAS  Google Scholar 

  4. 4

    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).

    ADS  CAS  Article  Google Scholar 

  5. 5

    Webb, R. S., Lehman, S. J., Rind, D. H., Healy, R. J. & Sigman, D. M. Influence of ocean heat transport on the climate of the Last Glacial Maximum. Nature 385, 695–699 (1997).

    ADS  CAS  Google Scholar 

  6. 6

    Broecker, W. S. Glacial to interglacial changes in oceanchemistry. Progr. Oceanogr. 2, 151–197 ( 1982).

    ADS  Google Scholar 

  7. 7

    Adams, J. M., Faure, H., Faure-Denard, L., McGlade, J. M. & Woodward, F. I. Increases in terrestrial carbon storage from the Last Glacial Maximum to the present. Nature 348, 711–714 (1990).

    ADS  CAS  Google Scholar 

  8. 8

    Crowley, T. J. Ice-Age terrestrial carbon changes revisited. Glob. Biogeochem. Cycles 9, 377–389 ( 1995).

    ADS  CAS  Google Scholar 

  9. 9

    Shackleton, N. J. in The Fate of Fossil Fuel CO2 in the Oceans (eds Sundquist, E. T. & Broecker, W. S.) 401–427 (American Geophysical Union, Washington DC, 1977).

    Google Scholar 

  10. 10

    Curry, W. B., Duplessy, J. C., Labeyrie, L. D. & Shackleton, N. J. Changes in the distribution of δ13C of deep water TCO 2 between the last glaciation and the Holocene. Paleoceanography 3, 317–341 ( 1988).

    ADS  Google Scholar 

  11. 11

    Duplessy, J. C. et al. Deepwater source variations during the last climatic cycle and their impact on the global deepwater circulation. Paleoceanography 3, 343–360 ( 1988).

    ADS  Google Scholar 

  12. 12

    Bird, M. I., Lloyd, J. & Farquhar, G. D. Terrestrial carbon storage at the LGM. Nature 371, 566 (1994).

    ADS  CAS  Google Scholar 

  13. 13

    Spero, H., Bijma, J., Lea, D. & Bemis, B. Effect of seawater carbonate concentration on foraminiferal carbon and oxygen isotopes. Nature 390, 497–500 ( 1997).

    ADS  CAS  Google Scholar 

  14. 14

    CLIMAP. The surface of the ice-age earth. Science 191, 1131– 1144 (1976).

    Google Scholar 

  15. 15

    Guilderson, T. P., Fairbanks, R. G. & Rubenstone, J. L. Tropical temperature variations since 20,000 years ago: modulating interhemispheric climate change. Science 263, 663–665 (1994).

    ADS  CAS  Google Scholar 

  16. 16

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

    ADS  Google Scholar 

  17. 17

    Broecker, W. S. et al. How strong is the Harvardton-Bear constraint? Glob. Biogeochem. Cycles 13, 817–820 (1999).

    ADS  CAS  Google Scholar 

  18. 18

    Fairbanks, R. G. A 17,000-year glacio-eustatic sea level record: Influence of glacial melting rates on the Younger Dryas event and deep-ocean circulation. Nature 342, 637–642 ( 1989).

    ADS  Google Scholar 

  19. 19

    Broecker, W. S. Ocean chemistry during glacial time. Geochim. Cosmochim. Acta 46, 1689–1706 (1982).

    ADS  CAS  Google Scholar 

  20. 20

    Berger, W. H. Increase of carbon dioxide in the atmosphere during deglaciation: The coral reef hypothesis. Naturwissenschaften 69, 87–88 (1982).

    ADS  CAS  Google Scholar 

  21. 21

    Broecker, W. S. & Peng, T.-H. The role of CaCO 3 compensation in the glacial to interglacial atmospheric CO2 change. Glob. Biogeochem. Cycles 1, 15– 29 (1987).

    ADS  CAS  Google Scholar 

  22. 22

    Milliman, J. D. Marine Carbonates (Springer, New York, 1974).

    Google Scholar 

  23. 23

    Edmond, J. M. et al. Ridge crest hydrothermal activity and the balances of the major and minor elements in the ocean: The Galapagos data. Earth Planet. Sci. Lett. 46, 1–18 (1979).

    ADS  CAS  Google Scholar 

  24. 24

    Sayles, F. L. & Mangelsdorf, P. C. Jr . The equilibration of clay minerals with seawater: exchange reactions. Geochim. Cosmochim. Acta 41, 951–960 ( 1977).

    ADS  CAS  Google Scholar 

  25. 25

    Berger, W. H. Planktonic foraminifera: selective solution and the lysocline. Mar. Geol. 8, 111–138 ( 1970).

    ADS  Google Scholar 

  26. 26

    Archer, D. Modeling the calcite lysocline. J. Geophys. Res. 96 , 17037–17050 (1991).

    ADS  Google Scholar 

  27. 27

    Broecker, W. S. & Takahashi, T. The relationship between lysocline depth and in situ carbonate ion concentration. Deep-Sea Res. 25, 65–95 (1978).

    CAS  Google Scholar 

  28. 28

    Broecker, W. S. in The Late Cenozoic Glacial Ages (ed. Turekian, K. K.) 239 –265 (Yale Univ. Press, New Haven, Connecticut, 1971).

    Google Scholar 

  29. 29

    Catubig, N. et al. Global deep-sea burial rate of calcium carbonate during the last glacial maximum. Paleoceanography 13, 298–310 (1998).

    ADS  Google Scholar 

  30. 30

    Archer, D. & Maier-Raimer, E. Effect of deep-sea sedimentary calcite preservation on atmospheric CO2 concentration. Nature 367, 260–263 ( 1994).

    ADS  CAS  Google Scholar 

  31. 31

    Dymond, J. & Lyle, M. Flux comparisons between sediments and sediment traps in the eastern tropical Pacific: Implications for atmospheric CO2 variations during the Pleistocene. Limnol. Oceanogr. 30, 699–712 ( 1985).

    ADS  CAS  Google Scholar 

  32. 32

    Keir, R. S. Is there a component of Pleistocene CO2 change associated with carbonate dissolution cycles? Paleoceanography 10, 871–880 (1995).

    ADS  Google Scholar 

  33. 33

    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).

    ADS  CAS  Google Scholar 

  34. 34

    Emerson, S. & Bender, M. L. Carbon fluxes at the sediment-water interface of the deep sea: calcium carbonate preservation. J. Mar. Res. 39, 139–162 ( 1981).

    CAS  Google Scholar 

  35. 35

    Hales, B. & Emerson, S. Calcite dissolution in sediments of the Ceara Rise: In situ measurements of porewater O2, pH, and CO2(aq). Geochim. Cosmochim. Acta 61, 501–514 (1997).

    ADS  CAS  Google Scholar 

  36. 36

    Redfield, A. C., Ketchum, B. H. & Richards, F. A. in The Sea (ed. Hill, M. N.) Vol. 2, 26–77 (Interscience, New York, 1963 ).

    Google Scholar 

  37. 37

    McElroy, M. B. Marine biological controls on atmospheric CO2 and climate. Nature 302, 328–329 ( 1983).

    ADS  CAS  Google Scholar 

  38. 38

    Chisholm, S. W. & Morel, F. M. M. (eds) What controls phytoplankton production in nutrient-rich areas of the open sea? Limnol. Oceanogr. 36(8) (special volume) 1507–1970 (1991).

    Google Scholar 

  39. 39

    Ruttenberg, K. C. Reassessment of the oceanic residence time of phosphorous. Chem. Geol. 107, 405–409 ( 1993).

    ADS  Google Scholar 

  40. 40

    Broecker, W. S. & Henderson, G. M. The sequence of events surrounding Termination II and their implications for the cause of glacial-interglacial CO2 changes. Paleoceanography 13, 352–364 ( 1998).

    ADS  Google Scholar 

  41. 41

    Gruber, N. & Sarmiento, J. L. Global patterns of marine nitrogen fixation and denitrification. Glob. Biogeochem. Cycles 11, 235–266 (1997).

    ADS  CAS  Google Scholar 

  42. 42

    Ganeshram, R. S., Pedersen, T. F., Calvert, S. E. & Murray, J. W. Large changes in oceanic nutrient inventories from glacial to interglacial periods. Nature 376, 755– 758 (1995).

    ADS  CAS  Google Scholar 

  43. 43

    Altabet, M. A., Francois, R., Murray, D. W. & Prell, W. L. Climate-related variations in denitrification in the Arabian Sea from sediment 15N/14N ratios. Nature 373, 506–509 (1995).

    ADS  CAS  Google Scholar 

  44. 44

    Pride, C. et al. Nitrogen isotopic variations in the Gulf of California since the last deglaciation: Response to global climate change. Paleoceanography 14, 397–409 ( 1999).

    ADS  Google Scholar 

  45. 45

    Falkowski, P. G. Evolution of the nitrogen cycle and its influence on the biological sequestration of CO2 in the ocean. Nature 387, 272–275 (1997).

    ADS  CAS  Google Scholar 

  46. 46

    Broecker, W. S. & Peng, T. -H. Tracers in the Sea (Eldigio, Palisades, New York, 1982).

    Google Scholar 

  47. 47

    Tyrrel, T. The relative influences of nitrogen and phosphorus on oceanic primary production. Nature 400, 525–531 (1999).

    ADS  Google Scholar 

  48. 48

    Karl, D. et al. The role of nitrogen fixation in biogeochemical cycling in the subtropical North Pacific Ocean. Nature 388, 533–538 (1997).

    ADS  CAS  Google Scholar 

  49. 49

    Haug, G. H. et al. Glacial/interglacial variations in productivity and nitrogen fixation in the Cariaco Basin during the last 550 ka. Paleoceanography 13, 427–432 ( 1998).

    ADS  Google Scholar 

  50. 50

    Pedersen, T. F. Increased productivity in the eastern equatorial Pacific during the last glacial maximum (19,000 to 14,000 yr B. P.). Geology 11, 16–19 (1983).

    ADS  CAS  Google Scholar 

  51. 51

    Berger, W. H., Herguera, J. C., Lange, C. B. & Schneider, R. in Carbon Cycling in the Glacial Ocean: Constraints on the Ocean's Role in Global Change (eds Zahn, R., Kaminski, M., Labeyrie, L. & Pederson, T. F.) 385–412 (Springer, New York, 1994).

    Google Scholar 

  52. 52

    Farrell, J. W., Pedersen, T. F., Calvert, S. E. & Nielsen, B. Glacial–interglacial changes in nutrient utilization in the equatorial Pacific Ocean. Nature 377, 514– 517 (1995).

    ADS  CAS  Google Scholar 

  53. 53

    Sanyal, A., Hemming, N. G., Broecker, W. S. & Hanson, G. N. Changes in pH in the eastern equatorial Pacific across stage 5-6 boundary based on boron isotopes in foraminifera. Glob. Biogeochem. Cycles 11, 125–133 ( 1997).

    ADS  CAS  Google Scholar 

  54. 54

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

    ADS  CAS  Google Scholar 

  55. 55

    Sarmiento, J. L. & Toggweiler, J. R. A new model for the role of the oceans in determining atmospheric p CO 2 . Nature 308, 621– 624 (1984).

    ADS  CAS  Google Scholar 

  56. 56

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

    ADS  CAS  Google Scholar 

  57. 57

    Broecker, W. S. & Peng, T.-H. The cause of the glacial to interglacial atmospheric CO2 change: A polar alkalinity hypothesis. Glob. Biogeochem. Cycles 3, 215–239 (1989).

    ADS  Google Scholar 

  58. 58

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

    ADS  Google Scholar 

  59. 59

    Francois, R. F. et al. Water column stratification in the Southern Ocean contributed to the lowering of glacial atmospheric CO2. Nature 389, 929–935 (1997).

    ADS  CAS  Google Scholar 

  60. 60

    Mortlock, R. A. et al. Evidence for lower productivity in the Antarctic during the last glaciation. Nature 351, 220– 223 (1991).

    ADS  Google Scholar 

  61. 61

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

    ADS  CAS  Google Scholar 

  62. 62

    Rosenthal, Y., Dahan, M. & Shemesh, A. Southern Ocean contributions to glacial-interglacial changes of atmospheric CO2: Evidence from carbon isotope records in diatoms. Paleoceanography 15, 65– 75 (2000).

    ADS  Google Scholar 

  63. 63

    Smith, H. J., Fischer, H., Wahlen, M., Mastroianni, D. & Deck, B. Dual modes of the carbon cycle since the Last Glacial Maximum. Nature 400, 248– 250 (1999).

    ADS  CAS  PubMed  Google Scholar 

  64. 64

    Di Tullio, G. R. et al. Rapid and early export of Phaeocystis antarctica blooms in the Ross Sea, Antarctica. Nature 404, 595 –598 (2000).

    ADS  CAS  Google Scholar 

  65. 65

    Moore, J. K., Abbott, M. R., Richman, J. G. & Nelson, D. M. The Southern Ocean at the last glacial maximum: A strong sink for atmospheric carbon dioxide. Glob. Biogeochem. Cycles 14, 455–475 (2000).

    ADS  CAS  Google Scholar 

  66. 66

    Sigman, D. M., Altabet, M. A., Francois, R., McCorkle, D. C. & Gaillard, J.-F. The isotopic composition of diatom-bound nitrogen in Southern Ocean sediments. Paleoceanography 14, 118–134 ( 1999).

    ADS  Google Scholar 

  67. 67

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

    ADS  Google Scholar 

  68. 68

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

    ADS  CAS  PubMed  Google Scholar 

  69. 69

    Boyle, E. A. Cadmium: Chemical tracer of deepwater paleoceanography. Paleoceanography 3, 471–489 ( 1988).

    ADS  Google Scholar 

  70. 70

    Keigwin, L. D. & Boyle, E. A. Late quaternary paleochemistry of high-latitude surface waters. Paleogeogr. Palaeoclim. Paleoecol. 73, 85–106 ( 1989).

    ADS  Google Scholar 

  71. 71

    Charles, C. D. & Fairbanks, R. G. in Geological History of the Polar Oceans: Arctic versus Antarctic (eds Bleil, U. & Thiede, J.) 519–538 (Kluwer Academic, Boston, 1988).

    Google Scholar 

  72. 72

    Elderfield, H. & Rickaby, R. E. M. Oceanic Cd/P ratio and nutrient utilization in the glacial Southern Ocean. Nature 405, 305–310 ( 2000).

    ADS  CAS  PubMed  Google Scholar 

  73. 73

    Broecker, W. S. & Maier-Reimer, E. The influence of air and sea exchange on the carbon isotope distribution in the sea. Glob. Biogeochem. Cycles 6, 315–320 (1992)..

    ADS  CAS  Google Scholar 

  74. 74

    Altabet, M. A. & Francois, R. Sedimentary nitrogen isotopic ratio as a recorder for surface ocean nitrate utilization. Glob. Biogeochem. Cycles 8, 103–116 (1994).

    ADS  CAS  Google Scholar 

  75. 75

    Sigman, D. M., Altabet, M. A., Francois, R., McCorkle, D. C. & Fischer, G. The δ15N of nitrate in the Southern Ocean: Consumption of nitrate in surface waters. Glob. Biogeochem. Cycles 13, 1149– 1166 (1999).

    ADS  CAS  Google Scholar 

  76. 76

    McCorkle, D. C., Martin, P. A., Lea, D. W. & Klinkhammer, G. P. Evidence of a dissolution effect on benthic foraminiferal shell chemistry: delta C-13, Cd/Ca, Ba/Ca, and Sr/Ca results from the Ontong Java plateau. Paleoceanography 10, 699– 714 (1995).

    ADS  Google Scholar 

  77. 77

    Kohfeld, K. E., Fairbanks, R. G., Smith, S. L. & Walsh, I. D. Neogloboquadrina pachyderma (sinistral coiling) as paleoceanographic tracers in polar oceans: Evidence from northeast water polynya plankton tows, sediment traps, and surface sediments. Paleoceanography 11, 679–699 (1996).

    ADS  Google Scholar 

  78. 78

    De La Rocha, C. L., Brzezinski, M. A., DeNiro, M. J. & Shemesh, A. Silicon-isotope composition of diatoms as an indicator of past oceanic change. Nature 395, 680–683 (1998).

    ADS  CAS  Google Scholar 

  79. 79

    Hutchins, D. A. & Bruland, K. W. Iron-limited diatom growth and Si:N uptake ratios in a coastal upwelling regime. Nature 393, 561–564 ( 1998).

    ADS  CAS  Google Scholar 

  80. 80

    Takeda, S. Influence of iron availability on nutrient consumption ratio of diatoms in oceanic waters. Nature 393, 774– 777 (1998).

    ADS  CAS  Google Scholar 

  81. 81

    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. Atmos. 104, 15895–15916 (1998).

    ADS  Google Scholar 

  82. 82

    Rosenthal, Y., Boyle, E. A. & Labeyrie, L. Last glacial maximum paleochemistry and deepwater circulation in the Southern Ocean: evidence from foraminiferal cadmium. Paleoceanography 12, 787–796 ( 1997).

    ADS  Google Scholar 

  83. 83

    Toggweiler, J. R., Carson, S. & Bjornsson, H. Response of the ACC and the Antarctic pycnocline to a meridional shift in the southern hemisphere westerlies. Eos 80, OS286 (1999).

    Google Scholar 

  84. 84

    Morley, J. J. & Hays, J. D. Oceanographic conditions associated with high abundances of the radiolarian Cycladophora davisiana. Earth Planet. Sci. Lett. 66, 63–72 (1983).

    ADS  Google Scholar 

  85. 85

    Sarmiento, J. L. & Orr, J. C. Three-dimensional simulations of the impact of Southern Ocean nutrient depletion on atmospheric CO2 and ocean chemistry. Limnol. Oceanogr. 36, 1928–1950 (1991).

    ADS  CAS  Google Scholar 

  86. 86

    Herguera, J. C., Jansen, E. & Berger, W. H. Evidence for a bathyal front at 2000 m depth in the glacial Pacific, based on a depth transect on Ontong Java Plateau. Paleoceanography 7, 273– 288 (1992).

    ADS  Google Scholar 

  87. 87

    Behl, R. J. & Kennett, J. P. Brief interstadial events in the Santa Barbara basin, NE Pacific, during the past 60 kyr. Nature 379, 243–246 ( 1996).

    ADS  CAS  Google Scholar 

  88. 88

    Boyle, E. A. The role of vertical chemical fractionation in controlling late quaternary atmospheric carbon dioxide. J. Geophys. Res. 93, 15701–15714 (1988).

    ADS  Google Scholar 

  89. 89

    Toggweiler, J. R. & Samuels, B. Effect of Drake Passage on the global thermohaline circulation. Deep-Sea Res. I 42, 477–500 ( 1998).

    Google Scholar 

  90. 90

    Gnanadesikan, A. A simple predictive model for the structure of the oceanic pycnocline. Science 283, 2077–2079 ( 1999).

    ADS  CAS  PubMed  Google Scholar 

  91. 91

    Boyle, E. A. & Keigwin, L. D. Deep circulation of the North Atlantic for the last 200,000 years: geochemical evidence. Science 218, 784–787 ( 1982).

    ADS  CAS  PubMed  Google Scholar 

  92. 92

    Leuenberger, M., Siegenthaler, U. & Langway, C. C. Carbon isotope composition of atmospheric CO 2 during the last Ice Age from an Antarctic ice core. Nature 357, 488–490 ( 1992).

    ADS  CAS  Google Scholar 

  93. 93

    Marino, B. D. & McElroy, M. B. Isotopic composition of atmospheric CO2 inferred from carbon in C4 plant cellulose. Nature 349, 127–131 ( 1991).

    ADS  CAS  Google Scholar 

  94. 94

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

    ADS  CAS  PubMed  Google Scholar 

  95. 95

    Sarmiento, J. L., Hughes, T. M. C., Stouffer, R. J. & Manabe, S. Response of the ocean carbon cycle to anthropogenic climate warming. Nature 393, 245–249 ( 1998).

    ADS  CAS  Google Scholar 

  96. 96

    Bassinot, F. C. et al. The astronomical theory of climate and the age of the Brunhes-Matuyama magnetic reversal. Earth Planet. Sci. Lett. 126, 91–108 (1994).

    ADS  Google Scholar 

  97. 97

    Holmen, K. in Global Biogeochemical Cycles (eds Butcher, S. S., Charlson, R. J., Orians, G. H. & Wolfe, G. V.) 239–262 (Academic, New York, 1992).

    Google Scholar 

  98. 98

    Honjo, S. in Particle Flux in the Ocean (eds Ittekkot, V., Schafer, P., Honjo, S. & Depetris, P. J.) (Wiley Interscience, Munich, 1996).

    Google Scholar 

  99. 99

    Oppo, D. W. & Lehman, S. J. Mid-depth circulation of the subpolar North Atlantic during the last glacial maximum. Science 259, 1148–1152 (1993).

    ADS  CAS  PubMed  Google Scholar 

  100. 100

    Keigwin, L. D. Glacial-age hydrography of the far northwest Pacific Ocean. Paleoceanography 13, 323–339 ( 1998).

    ADS  Google Scholar 

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We thank R. F. Anderson, M. L. Bender, M. A. Brzezinski and J. R. Toggweiler for discussions. We are indebted to P. G. Falkowski, G.M. Henderson and C. Prentice for comments on the manuscript.

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Correspondence to Daniel M. Sigman.

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

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