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Abrupt reversal in ocean overturning during the Palaeocene/Eocene warm period


An exceptional analogue for the study of the causes and consequences of global warming occurs at the Palaeocene/Eocene Thermal Maximum, 55 million years ago. A rapid rise of global temperatures during this event accompanied turnovers in both marine1,2,3 and terrestrial biota4, as well as significant changes in ocean chemistry5,6 and circulation7,8. Here we present evidence for an abrupt shift in deep-ocean circulation using carbon isotope records from fourteen sites. These records indicate that deep-ocean circulation patterns changed from Southern Hemisphere overturning to Northern Hemisphere overturning at the start of the Palaeocene/Eocene Thermal Maximum. This shift in the location of deep-water formation persisted for at least 40,000 years, but eventually recovered to original circulation patterns. These results corroborate climate model inferences that a shift in deep-ocean circulation would deliver relatively warmer waters to the deep sea, thus producing further warming9. Greenhouse conditions can thus initiate abrupt deep-ocean circulation changes in less than a few thousand years, but may have lasting effects; in this case taking 100,000 years to revert to background conditions.

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Figure 1: Compilation of carbon isotope records.
Figure 2: Selected carbon isotope records on a common timescale.
Figure 3: Deep-ocean circulation flow paths based on carbon isotopes.
Figure 4: Isotope stratigraphy for Southern Ocean Site ODP 690 (blue symbols) and North Atlantic Site DSDP 401 (red symbols).


  1. Kelly, D. C., Bralower, T. J. & Zachos, J. C. Evolutionary consequences of the latest Paleocene thermal maximum for tropical planktonic foraminifera. Palaeogeogr. Palaeoclimatol. Palaeoecol. 141, 139–161 (1998)

    Article  Google Scholar 

  2. Bralower, T. J. Evidence of surface water oligotrophy during the Paleocene-Eocene thermal maximum: Nannofossil assemblage data from Ocean Drilling Program Site 690, Maud Rise, Weddell Sea. Paleoceanography 17, doi:10.1029/2001PA000662 (2002)

  3. Crouch, E. M. et al. Global dinoflagellate event associated with the late Paleocene thermal maximum. Geology 29, 315–318 (2001)

    Article  ADS  CAS  Google Scholar 

  4. Bowen, G. J. et al. Mammalian dispersal at the Paleocene/Eocene boundary. Science 295, 2062–2065 (2002)

    Article  ADS  CAS  Google Scholar 

  5. Dickens, G. R., Castillo, M. M. & Walker, J. C. G. A blast of gas in the latest Paleocene; simulating first-order effects of massive dissociation of oceanic methane hydrate. Geology 25, 259–262 (1997)

    Article  ADS  CAS  Google Scholar 

  6. Zachos, J. C. et al. Rapid acidification of the ocean during the Paleocene-Eocene thermal maximum. Science 308, 1611–1615 (2005)

    Article  ADS  CAS  Google Scholar 

  7. Kennett, J. P. & Stott, L. D. Abrupt deep-sea warming, palaeoceanographic changes and benthic extinctions at the end of the Palaeocene. Nature 353, 225–229 (1991)

    Article  ADS  Google Scholar 

  8. Pak, D. K. & Miller, K. G. Paleocene to Eocene benthic foraminiferal isotopes and assemblages; implications for deepwater circulation. Paleoceanography 7, 405–422 (1992)

    Article  ADS  Google Scholar 

  9. Bice, K. L. & Marotzke, J. Could changing ocean circulation have destabilized methane hydrate at the Paleocene/Eocene boundary? Paleoceanography 17, 8.1–8.13 (2002)

    Article  Google Scholar 

  10. Kennett, J. P. et al. Proteus and Proto-Oceanus; ancestral Paleogene oceans as revealed from Antarctic stable isotopic results; ODP Leg 113. Proc. ODP Sci. Res. 113, 865–880 (1990)

    Google Scholar 

  11. Kroopnick, P. M. The distribution of 13C of ΣCO2 in the world oceans. Deep-Sea Res. Part A 32, 57–84 (1985)

    Article  ADS  CAS  Google Scholar 

  12. Quillevere, F., Aubry, M. P., Norris, R. D. & Berggren, W. A. Paleocene oceanography of the eastern subtropical Indian Ocean—An integrated magnetobiostratigraphic and stable isotope study of ODP Hole 761B (Wornbat Plateau). Palaeogeogr. Palaeoclimatol. Palaeoecol. 184, 371–405 (2002)

    Article  Google Scholar 

  13. Bowen, G. J., Beerling, D. J., Koch, P. L., Zachos, J. C. & Quattlebaum, T. A humid climate state during the Palaeocene/Eocene thermal maximum. Nature 432, 495–499 (2004)

    Article  ADS  CAS  Google Scholar 

  14. Thomas, D. J., Bralower, T. J. & Jones, C. E. Neodymium isotopic reconstruction of late Paleocene-early Eocene thermohaline circulation. Earth Planet. Sci. Lett. 209, 309–322 (2003)

    Article  ADS  CAS  Google Scholar 

  15. Brady, E. C., DeConto, R. M. & Thompson, S. L. Deep water formation and poleward ocean heat transport in the warm climate extreme of the Cretaceous (80 Ma). Geophys. Res. Lett. 25, 4205–4208 (1998)

    Article  ADS  Google Scholar 

  16. Bice, K. L. & Marotzke, J. Numerical evidence against reversed thermohaline circulation in the warm Paleocene/Eocene ocean. J. Geophys. Res. 106, 11529–11542 (2001)

    Article  ADS  Google Scholar 

  17. Bains, S., Norris, R. D., Corfield, R. M. & Faul, K. L. Termination of global warmth at the Palaeocene/Eocene boundary through productivity feedback. Nature 407, 171–174 (2000)

    Article  ADS  CAS  Google Scholar 

  18. Beerling, D. J. Increased terrestrial carbon storage across the Palaeocene-Eocene boundary. Palaeogeogr. Palaeoclimatol. Palaeoecol. 161, 395–405 (2000)

    Article  Google Scholar 

  19. Ravizza, G., Norris, R. N., Blusztajn, J. & Aubry, M. P. An osmium isotope excursion associated with the late Paleocene thermal maximum: Evidence of intensified chemical weathering. Paleoceanography 16, 155–163 (2001)

    Article  ADS  Google Scholar 

  20. Stoll, H. M. & Bains, S. Coccolith Sr/Ca records of productivity during the Paleocene-Eocene thermal maximum from the Weddell Sea. Paleoceanography 18, doi:10.1029/2002PA000875 (2003)

  21. Rohl, U., Bralower, T. J., Norris, R. D. & Wefer, G. New chronology for the late Paleocene thermal maximum and its environmental implications. Geology 28, 927–930 (2000)

    Article  ADS  CAS  Google Scholar 

  22. Norris, R. D. & Rohl, U. Carbon cycling and chronology of climate warming during the Palaeocene/Eocene transition. Nature 401, 775–778 (1999)

    Article  ADS  CAS  Google Scholar 

  23. Wing, S. L., Bao, H. & Koch, P. L. in Warm Climates in Earth History (eds Huber, B. T., MacLeod, K. G. & Wing, S. L.) 197–237 (Univ. Cambridge, Cambridge, UK, 2000)

    Google Scholar 

  24. Farley, K. A. & Eltgroth, S. F. An alternative age model for the Paleocene-Eocene thermal maximum using extraterrestrial He-3. Earth Planet. Sci. Lett. 208, 135–148 (2003)

    Article  ADS  CAS  Google Scholar 

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We thank C. Charles for discussions and for assistance with the mass spectrometer at SIO, and P. Worstell for assistance in the laboratory. This research used samples and data provided by the Ocean Drilling Program (ODP). ODP is sponsored by the US National Science Foundation (NSF) and participating countries under management of Joint Oceanographic Institutions (JOI), Inc. Funding for this research was provided by the National Science Foundation and the US Science Support Program (to RDN). Author Contributions F.N. performed the data acquisition, and manuscript preparation; R.D.N. was responsible for project planning, manuscript revision and financial support. Both authors contributed equally in data analysis and interpretation.

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Correspondence to Flavia Nunes.

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Supplementary information

Supplementary Table 1

This table contains all stable isotope data from benthic foraminifera presented in this paper. The table also includes the age estimate for each sample, based on the chronology developed for this study. (XLS 88 kb)

Supplementary Notes

List of references for Supplementary Table 1. (DOC 21 kb)

Supplementary Table 2

This table contains the average carbon isotope value for each site for each time interval along with standard deviation and number of data points used for each average. The table also presents basin averages and interbasinal aging gradients with standard deviation. (XLS 23 kb)

Supplementary Table 3

This table lists the data excluded from the deep ocean circulation analysis with a description of why the data were deemed unreliable. (DOC 24 kb)

Supplementary Notes

This is a summary of the biostratigraphic datums available for correlation of the core of the carbon isotope excursion, and why they were deemed unsuitable for correlating the sites presented in this study. (DOC 32 kb)

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Nunes, F., Norris, R. Abrupt reversal in ocean overturning during the Palaeocene/Eocene warm period. Nature 439, 60–63 (2006).

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