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Migration of the subtropical front as a modulator of glacial climate


Ice cores extracted from the Antarctic ice sheet suggest that glacial conditions, and the relationship between isotopically derived temperatures and atmospheric have been constant over the last 800,000 years of the Late Pleistocene epoch1. But independent lines of evidence, such as the extent of Northern Hemisphere ice sheets2, sea level3 and other temperature records4, point towards a fluctuating severity of glacial periods, particularly during the more extreme glacial stadials centred around 340,000 and 420,000 years ago (marine isotope stages 10 and 12). Previously unidentified mechanisms therefore appear to have mediated the relationship between insolation, CO2 and climate. Here we test whether northward migration of the subtropical front (STF) off the southeastern coast of South Africa acts as a gatekeeper for the Agulhas current5,6, which controls the transport of heat and salt from the Indo-Pacific Ocean to the Atlantic Ocean. Using a new 800,000-year record of sea surface temperature and ocean productivity from ocean sediment core MD962077, we demonstrate that during cold stadials (particularly marine isotope stages 10 and 12), productivity peaked and sea surface temperature was up to 6 °C cooler than modern temperatures. This suggests that during these cooler stadials, the STF moved northward by up to 7° latitude, nearly shutting off the Agulhas current. Our results, combined with faunal assemblages from the south Atlantic7,8 show that variable northwards migration of the Southern Hemisphere STF can modulate the severity of each glacial period by altering the strength of the Agulhas current carrying heat and salt to the Atlantic meridional overturning circulation. We show hence that the degree of northwards migration of the STF can partially decouple global climate from atmospheric partial pressure of carbon dioxide, , and help to resolve the long-standing puzzle of differing glacial amplitudes within a consistent range of atmospheric .

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Figure 1: SeaWiFS (Sea-viewing Wide Field-of-view Sensor) image of ocean colour during austral summer with the highly productive STF to the south of core MD962077 (red star).
Figure 2: Long-term trends in SST and productivity-sensitive parameters from core MD962077 compared to the stable baseline glacial temperatures recorded in EPICA Dome C.
Figure 3: Mechanistic link between the migration of the STF, orbital eccentricity and ocean overturning.


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

    Article  ADS  Google Scholar 

  2. Svendsen, J. I. et al. The Quaternary ice sheet history of northern Eurasia. Quat. Sci. Rev. 23, 1229–1271 (2004)

    Article  ADS  Google Scholar 

  3. Rohling, E. J. et al. Magnitude of sea-level lowstands of the past 500,000 years. Nature 394, 162–165 (1998)

    Article  CAS  ADS  Google Scholar 

  4. McManus, J. F. et al. A 0.5-million-year record of millennial-scale climate variability in the North Atlantic. Science 283, 971–975 (1999)

    Article  CAS  ADS  Google Scholar 

  5. Lutjeharms, J. R. E. in The South Atlantic: Present and Past Circulation (eds Wefer, G., Berger, W. H., Siedler, G. & Webb, D.) 125–162 (Springer, 1996)

    Book  Google Scholar 

  6. Biastoch, A., Boning, C. W. & Lutjeharms, J. R. E. Agulhas leakage dynamics affects decadal variability in Atlantic overturning circulation. Nature 456, 489–492 (2008)

    Article  CAS  ADS  Google Scholar 

  7. Flores, J. A., Gersonde, R. & Sierro, F. J. Pleistocene fluctuations in the Agulhas Current Retroflection based on the calcareous plankton record. Mar. Micropaleontol. 37, 1–22 (1999)

    Article  ADS  Google Scholar 

  8. Peeters, F. J. C. et al. Vigorous exchange between the Indian and Atlantic Oceans at the end of the past five glacial periods. Nature 430, 661–665 (2004)

    Article  CAS  ADS  Google Scholar 

  9. Howard, W. R. & Prell, W. L. Late Quaternary Surface circulation of the Southern Indian Ocean and its relationship to orbital variations. Paleoceanography 7, 79–117 (1992)

    Article  ADS  Google Scholar 

  10. Berger, W. H. & Wefer, G. in The South Atlantic: Present and Past Circulation (eds Wefer, G., Berger, W. H., Siedler, G. & Webb, D. J.) 363–410 (Springer, 1996)

    Book  Google Scholar 

  11. Bé, A. W. & Duplessy, J. C. Subtropical convergence fluctuations and quaternary climates in the middle latitudes of the Indian Ocean. Science 194, 419–422 (1976)

    Article  ADS  Google Scholar 

  12. Rau, A., Rogers, J. & Chen, M.-T. Quaternary palaeoceanographic record in giant piston cores off South Africa, possibly include evidence of neotectonism. Quat. Int. 148, 65–77 (2006)

    Article  Google Scholar 

  13. Ledru, M. P., Rousseau, D. D., Riccomini, F. W. C., Karmann, I. & Martin, L. Paleoclimate changes during the last 100,000 yr from a record in the Brazilian Atlantic rainforest region and interhemispheric comparison. Quat. Res. 64, 444–450 (2005)

    Article  Google Scholar 

  14. Menviel, L., Timmerman, A., Mouchet, A. & Timm, O. Climate and marine carbon cycle response to changes in the strength of the Southern Hemispheric westerlies. Paleoceanography 23 10.1029/2008PA001604 (2008)

  15. Rojas, M. et al. The Southern Westerlies during the last glacial maximum in PMIP2 simulations. Clim. Dyn. 10.1007/s00382–008–0421–7 (2008)

  16. Kuhlbrodt, K. et al. On the driving processes of the Atlantic Meridional Overturning Circulation. Rev. Geophys. 45, RG2001 (2004)

    ADS  Google Scholar 

  17. Gordon, A. L. Interocean exchange of thermocline water. J. Geophys. Res. 91, 5037–5046 (1986)

    Article  ADS  Google Scholar 

  18. Weijer, W., de Ruijter, W. P. M., Sterl, A. & Drujfhout, S. S. Response of the Atlantic overturning circulation to South Atlantic sources of buoyancy. Global Planet. Change 34, 293–311 (2002)

    Article  ADS  Google Scholar 

  19. Knorr, G. & Lohmann, G. Southern Ocean origin for the resumption of Atlantic thermohaline circulation during deglaciation. Nature 424, 532–536 (2003)

    Article  CAS  ADS  Google Scholar 

  20. Sijp, W. P. & England, M. H. Southern Hemisphere westerly wind control over the ocean’s thermohaline circulation. J. Clim. (in the press)

  21. Toggweiler, J. R. & Russell, J. Ocean circulation in a warming climate. Nature 451, 286–288 (2008)

    Article  CAS  ADS  Google Scholar 

  22. 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 10.1029/2002GC000367 (2002)

  23. Williams, G. P. & Bryan, K. Ice age winds: an aquaplanet model. J. Clim. 19, 1706–1715 (2006)

    Article  ADS  Google Scholar 

  24. Masson-Delmotte, V. et al. EPICA Dome C record of glacial and interglacial intensities. Quat. Sci. Rev. (in the press)

  25. Rickaby, R. E. M. et al. Coccolith chemistry reveals secular variations in the global ocean carbon cycle? Earth Planet. Sci. Lett. 253, 83–95 (2007)

    Article  CAS  ADS  Google Scholar 

  26. Short, D. A., Mengel, J. G., Crowley, T. J., Hyde, W. T. & North, G. R. Filtering of Milankovitch cycles by Earths geography. Quat. Res. 35, 157–173 (1991)

    Article  Google Scholar 

  27. Berger, A., Loutre, M. F. & Melice, J. L. Equatorial insolation: from precession harmonics to eccentricity frequencies. Clim. Past 2, 131–136 (2006)

    Article  Google Scholar 

  28. Ashkenazy Y & Gildor, H. Timing and significance of maximum and minimum equatorial insolation. Paleoceanography 23 PA1206 1029/2007001436 (2008)

    Article  ADS  Google Scholar 

  29. Schmittner, A., Yoshimori, M. & Weaver, A. J. Instability of glacial climate in a model of the ocean-atmosphere-cryosphere system. Science 295, 1489–1493 (2002)

    Article  CAS  ADS  Google Scholar 

  30. Ganopolski, A. & Rahmstorf, S. Rapid changes of glacial climate simulated in a coupled climate model. Nature 409, 153–158 (2001)

    Article  CAS  ADS  Google Scholar 

  31. Raymo, M. E. et al. Stability of North Atlantic water masses in face of pronounced climate variability during the Pleistocene. Paleoceanography 19 PA2008 10.1029/2003PA000921 (2004)

    Article  ADS  Google Scholar 

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

    ADS  Google Scholar 

  33. Sonzogni, C. et al. Core-top calibration of the alkenone index vs sea surface temperature in the Indian Ocean. Deep-Sea Res. 44, 1445–1460 (1997)

    CAS  ADS  Google Scholar 

  34. Pailler, D. & Bard, E. High frequency paleoceanographic changes during the past 140,000 years recorded by the organic matter in sediments off the Iberian Margin. Palaeogeogr. Palaeoclim. Palaeoecol. 181, 431–452 (2002)

    Article  ADS  Google Scholar 

  35. Rosell-Melé, A. et al. Precision of the current methods to measure the alkenone proxy UK37' and absolute abundance in sediments: results of an interlaboratory comparison study. Geochem. Geophys. Geosyst. 2, 2000GC000141, 1–28 (2001)

    Article  Google Scholar 

  36. Prahl, F. G., Muehlhausen, L. A. & Zahnle, D. L. Further evaluation of long-chain alkenones as indicators of paleoceanographic conditions. Geochim. Cosmochim. Acta 52, 2303–2310 (1988)

    Article  CAS  ADS  Google Scholar 

  37. Müller, P. J., Kirst, G., Ruhland, G., von Storch, I. & Rosell-Mele, A. Calibration of the alkenone paleotemperature index Uk37’ based on core-tops from the eastern South Atlantic and the global ocean (60°N–60°S). Geochim. Cosmochim. Acta 62, 1757–1772 (1998)

    Article  ADS  Google Scholar 

  38. Conte, M., Thompson, A., Lesley, D. & Harris, R. P. Genetic and physiological influences on the alkenone/alkenoate versus growth temperature relationship in Emiliania huxleyi and Gephyrocapsa oceanica. Geochim. Cosmochim. Acta 62, 51–68 (1998)

    Article  CAS  ADS  Google Scholar 

  39. Stoll, H. M. & Schrag, D. P. Coccolith Sr/Ca as a new indicator of coccolithophorid calcification and growth rate. Geochem. Geophys. Geosyst. 1 10.1029/1999GC000015 (2000)

  40. Ziveri, P. et al. Stable isotope “vital effects” in coccolith calcite. Earth Planet. Sci. Lett. 210, 137–149 (2003)

    Article  CAS  ADS  Google Scholar 

  41. Bard, E. Paleoceanographic implications of the difference in deep-sea sediment mixing between large and fine particles. Paleoceanography 16, 235–239 (2001)

    Article  ADS  Google Scholar 

  42. Pailler, D. et al. Burial of redox-sensitive metals and organic matter in the equatorial Indian Ocean linked to precession. Geochim. Cosmochim. Acta 66, 849–865 (2002)

    Article  CAS  ADS  Google Scholar 

  43. Taylor, S. R. & McLennan, S. M. The Continental Crust: Its Composition and Evolution (Blackwell, 1985)

    Google Scholar 

  44. Rosenthal, Y., Boyle, E. A., Labeyrie, L. & Oppo, D. Glacial enrichments of authigenic Cd and U in subantarctic sediments—a climatic control on the element’s oceanic budget. Paleoceanography 10, 395–413 (1995)

    Article  ADS  Google Scholar 

  45. Sachs, J. P. & Anderson, R. F. Increased productivity in the Subantarctic ocean during Heinrich events. Nature 434, 1118–1121 (2005)

    Article  CAS  ADS  Google Scholar 

  46. Schulte, S. & Bard, E. Past changes in biologically mediated dissolution of calcite above the chemical lysocline recorded in Indian ocean sediments. Quat. Sci. Rev. 22, 1757–1770 (2003)

    Article  ADS  Google Scholar 

  47. Zheng, Y., Anderson, R. F., Van Geen, A. & Fleisher, M. Q. Remobilization of authigenic uranium in marine sediments by bioturbation. Geochim. Cosmochim. Acta 66, 1759–1772 (2002)

    Article  CAS  ADS  Google Scholar 

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We thank D. P. Schrag and E. Goddard for their help with analyses in the early stages of this work. We thank C. Sonzogni, F. Rostek, N. Thouveny and J. Carignan for help with analyses and age model, and D. Sansom for help with the figures. We also thank H. Gildor, Y. Ashkenazy, R. Toggweiler, M. Meredith, M.-F. Loutre, P. Huybers and N. Edwards for comments and discussion on an earlier version of this manuscript. R.E.M.R. is grateful to the Royal Society for the International Outgoing Visit award for the exchange visits to CEREGE, which facilitated the development of the ideas and the manuscript. Palaeoclimate work at CEREGE is supported by grants from the Gary Comer Foundation, the CNRS and the Collège de France. Core MD962077 was collected by the RV Marion Dufresne supported by the Institut Polaire Français (IPEV).

Author Contributions E.B. and R.E.M.R. contributed equally to this work.

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Correspondence to Edouard Bard or Rosalind E. M. Rickaby.

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This file contains the dataset for core MD962077. (XLS 29 kb)

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Bard, E., Rickaby, R. Migration of the subtropical front as a modulator of glacial climate. Nature 460, 380–383 (2009).

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