Letter | Published:

Very large release of mostly volcanic carbon during the Palaeocene–Eocene Thermal Maximum

Nature volume 548, pages 573577 (31 August 2017) | Download Citation


The Palaeocene–Eocene Thermal Maximum1,2 (PETM) was a global warming event that occurred about 56 million years ago, and is commonly thought to have been driven primarily by the destabilization of carbon from surface sedimentary reservoirs such as methane hydrates3. However, it remains controversial whether such reservoirs were indeed the source of the carbon that drove the warming1,3,4,5. Resolving this issue is key to understanding the proximal cause of the warming, and to quantifying the roles of triggers versus feedbacks. Here we present boron isotope data—a proxy for seawater pH—that show that the ocean surface pH was persistently low during the PETM. We combine our pH data with a paired carbon isotope record in an Earth system model in order to reconstruct the unfolding carbon-cycle dynamics during the event6,7. We find strong evidence for a much larger (more than 10,000 petagrams)—and, on average, isotopically heavier—carbon source than considered previously8,9. This leads us to identify volcanism associated with the North Atlantic Igneous Province10,11, rather than carbon from a surface reservoir, as the main driver of the PETM. This finding implies that climate-driven amplification of organic carbon feedbacks probably played only a minor part in driving the event. However, we find that enhanced burial of organic matter seems to have been important in eventually sequestering the released carbon and accelerating the recovery of the Earth system12.

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This study was funded by a UK Ocean Acidification Research Program NERC/DEFRA/DECC grant (NE/H017518/1) to P.N.P., G.L.F. and P.F.S. (also supporting M.G.). A.R. was supported by a Heising–Simons Foundation award, and by EU grant ERC 2013-CoG-617313. E.T. was in part supported by the National Science Foundation Division of Ocean Sciences (grant no. NSF OCE 1536611). H.P. was in part supported by ERC grant 2013-CoG-617462. This study used samples provided by the International Ocean Discovery Program. We thank A. Milton at the University of Southampton for maintaining the mass spectrometers used in this study, and M. Davies at The Open University for assistance with sample preparation. We thank L. Haxhiaj and D. Nürnberg at GEOMAR Kiel and H. Kuhnert at MARUM Bremen for their help with carbon and oxygen isotope analyses.

Author information


  1. Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton SO17 1BJ, UK

    • Marcus Gutjahr
    • , Eleni Anagnostou
    •  & Gavin L. Foster
  2. GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstrasse 1–3, 24148 Kiel, Germany

    • Marcus Gutjahr
  3. School of Geographical Sciences, Bristol University, Bristol BS8 1SS, UK

    • Andy Ridgwell
  4. Department of Earth Sciences, University of California at Riverside, Riverside, California 92521, USA

    • Andy Ridgwell
  5. School of Environment, Earth and Ecosystem Sciences, The Open University, Milton Keynes MK7 6AA, UK

    • Philip F. Sexton
  6. School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK

    • Paul N. Pearson
  7. MARUM, Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany

    • Heiko Pälike
  8. Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92037, USA

    • Richard D. Norris
  9. Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06520, USA

    • Ellen Thomas
  10. Department of Earth and Environmental Sciences, Wesleyan University, Middletown, Connecticut 06459, USA

    • Ellen Thomas


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G.L.F., P.F.S. and P.N.P. developed the concept and designed the study. M.G. and E.A. carried out the preparation of chemical samples, as well as elemental and isotopic analyses. P.F.S. performed foraminifer taxonomy and prepared foraminifer samples for the analyses. R.D.N. and E.T. supplied washed coarse-fraction samples. P.F.S. developed the age model. A.R. devised and conducted the Earth system modelling and analysis. H.P. carried out the carbon and oxygen isotopic analyses. M.G., A.R., G.L.F. and P.F.S. led the writing of the manuscript. All authors contributed to the interpretation of results and writing of the final text.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Marcus Gutjahr.

Reviewer Information Nature thanks T. Bralower, K. Meissner and the other anonymous reviewer(s) for their contribution to the peer review of this work.

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Extended data

Supplementary information

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  1. 1.

    Supplementary Information

    This file contains a detailed account about the Earth System Modelling approaches that were used and additional references.

Excel files

  1. 1.

    Supplementary Table 1

    This table contains foraminifera-based stable isotope results, relative sample ages, selected elemental ratios as well as the calculated mixed layer pH.

  2. 2.

    Supplementary Table 2

    This table contains bulk carbonate stable carbon and oxygen isotope results, presented alongside relative ages following our two alternative age models (see Methods).

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