Slow release of fossil carbon during the Palaeocene–Eocene Thermal Maximum

Journal name:
Nature Geoscience
Year published:
Published online


The transient global warming event known as the Palaeocene–Eocene Thermal Maximum occurred about 55.9Myr ago. The warming was accompanied by a rapid shift in the isotopic signature of sedimentary carbonates, suggesting that the event was triggered by a massive release of carbon to the ocean–atmosphere system. However, the source, rate of emission and total amount of carbon involved remain poorly constrained. Here we use an expanded marine sedimentary section from Spitsbergen to reconstruct the carbon isotope excursion as recorded in marine organic matter. We find that the total magnitude of the carbon isotope excursion in the ocean–atmosphere system was about 4‰. We then force an Earth system model of intermediate complexity to conform to our isotope record, allowing us to generate a continuous estimate of the rate of carbon emissions to the atmosphere. Our simulations show that the peak rate of carbon addition was probably in the range of 0.3–1.7PgCyr−1, much slower than the present rate of carbon emissions.

At a glance


  1. Study area.
    Figure 1: Study area.

    a, Location map showing Palaeogene deposits in Spitsbergen. The red square represents the location of the study area near Sveagruva and Urdkollbreen. The drill core (BH9-05) site is located on the eastern margin of the Palaeogene Central Basin (77°50′N,16°30′E). b, Stratigraphy of the Van Mijenfjorden Group (modified from refs 16 and 17). Core BH9-05 is shown as a red rectangle, which spans the Palaeocene/Eocene boundary. The geochemical and isotopic analyses in this study are from the blue highlighted interval.

  2. Geochemical profiles throughout the PETM from core BH9-05 in Spitsbergen.
    Figure 2: Geochemical profiles throughout the PETM from core BH9-05 in Spitsbergen.

    a, Carbon isotopes of total organic carbon (δ13CTOC). b, Pristane and phytane ratio denoted by Pr/Ph. c, Weight percentage of total organic carbon (wt% TOC), red dots are from this study, whereas blue dots are from ref. 18. d, Corg/Nbulk atomic ratio. eδ15N (‰) of bulk decarbonated sediment.

  3. Filtered records of core BH9-05 in the depth domain modified from ref. 
    Figure 3: Filtered records of core BH9-05 in the depth domain modified from ref.  2.

    aδ13CTOC (‰) from this study. b, Core BH9-05 Log Fe (red) and Mn (blue) time series. c, Log Fe and Mn 4.2m (0.24±0.07cyclesm−1) Gaussian filter output. Numbered cycles were interpreted as precession cycles and tuned to the Log Fe record from ODP Site 1263 (ref. 1) to derive the age model used in this study (Option A of ref. 2). d, Log Fe and Mn 20m (0.05±0.01cyclesm−1) filter, inferred to represent the short (~100kyr) component of orbital forcing.

  4. Model results of the PETM carbon release rate and cumulative amount of carbon added versus time from the onset of the CIE (535[thinsp]mbs) (age model is from ref. 
    Figure 4: Model results of the PETM carbon release rate and cumulative amount of carbon added versus time from the onset of the CIE (535mbs) (age model is from ref.  2).

    aδ13Catm that we used to force GENIE. b, Model results of the PETM carbon release rate. c, Model results of the cumulative amount of carbon added. d, Model results of the PETM atmospheric pCO2. e, Model results of the PETM global average temperature (°C). The two best-fit simulations are shown in be:(1) CH4 simulation (black solid line); (2) Corg simulation (red dotted line). Both simulations are with bioturbation on.


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Author information


  1. Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania 16802, USA

    • Ying Cui,
    • Lee R. Kump,
    • Christopher K. Junium,
    • Aaron F. Diefendorf,
    • Katherine H. Freeman &
    • Nathan M. Urban
  2. School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK

    • Andy J. Ridgwell
  3. School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, European Way, Southampton SO14 3ZH, UK

    • Adam J. Charles &
    • Ian C. Harding
  4. Present address: Department of Earth and Planetary Science, Northwestern University, Evanston, Illinois 60208, USA

    • Christopher K. Junium
  5. Present address: Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221, USA

    • Aaron F. Diefendorf
  6. Present address: Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, New Jersey 08544, USA

    • Nathan M. Urban


L.R.K., Y.C. and A.J.R. designed the research. Y.C. carried out all the model simulations. Y.C., C.K.J. and A.F.D. conducted geochemical analyses. Y.C. and L.R.K. wrote the paper with contributions from A.J.C., C.K.J. and A.F.D. All authors contributed to interpretation of data.

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The authors declare no competing financial interests.

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