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Eocene global warming events driven by ventilation of oceanic dissolved organic carbon


‘Hyperthermals’ are intervals of rapid, pronounced global warming known from six episodes within the Palaeocene and Eocene epochs (65–34 million years (Myr) ago)1,2,3,4,5,6,7,8,9,10,11,12,13. The most extreme hyperthermal was the 170 thousand year (kyr) interval2 of 5–7 °C global warming3 during the Palaeocene–Eocene Thermal Maximum (PETM, 56 Myr ago). The PETM is widely attributed to massive release of greenhouse gases from buried sedimentary carbon reservoirs1,3,6,11,14,15,16,17, and other, comparatively modest, hyperthermals have also been linked to the release of sedimentary carbon3,6,11,16,17. Here we show, using new 2.4-Myr-long Eocene deep ocean records, that the comparatively modest hyperthermals are much more numerous than previously documented, paced by the eccentricity of Earth’s orbit and have shorter durations (40 kyr) and more rapid recovery phases than the PETM. These findings point to the operation of fundamentally different forcing and feedback mechanisms than for the PETM, involving redistribution of carbon among Earth’s readily exchangeable surface reservoirs rather than carbon exhumation from, and subsequent burial back into, the sedimentary reservoir. Specifically, we interpret our records to indicate repeated, large-scale releases of dissolved organic carbon (at least 1,600 gigatonnes) from the ocean by ventilation (strengthened oxidation) of the ocean interior. The rapid recovery of the carbon cycle following each Eocene hyperthermal strongly suggests that carbon was re-sequestered by the ocean, rather than the much slower process of silicate rock weathering proposed for the PETM1,3. Our findings suggest that these pronounced climate warming events were driven not by repeated releases of carbon from buried sedimentary sources3,6,11,16,17, but, rather, by patterns of surficial carbon redistribution familiar from younger intervals of Earth history.

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Figure 1: High-resolution records across the early Eocene to middle Eocene transition from ODP Site 1258, Demerara rise, tropical Atlantic.
Figure 2: Details of stable isotope data from ODP Site 1258 across two ‘hyperthermal’ events.
Figure 3: Eocene records of benthic foraminifer δ 13 C and CaCO 3 dissolution.


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We thank M. Bolshaw for laboratory assistance and the shipboard party and crew of Ocean Drilling Program (ODP) Leg 207 for a successful drilling expedition. We thank H. Brinkhuis, G. Dickens, G. Foster, M. Huber, S. Kirtland, D. Kroon, L. Kump, E. Rohling and J. Zachos for discussions. This research used samples and data provided by the ODP. ODP (now IODP) is sponsored by the US NSF and participating countries under the management of JOI, Inc. We thank W. Hale and A. Wülbers (IODP) for assistance with sediment core sampling. Financial support for this research was provided by a European Commission Marie Curie Outgoing International Fellowship (P.F.S.), a Leverhulme Trust Fellowship (P.F.S.), a Natural Environment Research Council UK ODP grant (P.A.W. and P.F.S.), a Philip Leverhulme Prize (H.P.), the DFG-Leibniz Center for Surface Process and Climate Studies at the University of Potsdam, and the DFG (U.R. and T.W.).

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Authors and Affiliations



P.F.S. and P.A.W. designed and instigated the research. P.F.S. and C.T.B. picked foraminifera. P.F.S. and P.A.W. generated stable isotope records. P.F.S. and H.P. generated the estimated CaCO3 content records and constructed age models. P.F.S. conducted stratigraphic correlations between the various drill sites. T.W. and U.R. modified the spliced sedimentary section at Demerara rise. S.G. generated biostratigraphic data for Demerara rise. P.F.S. and R.D.N. wrote the manuscript. P.A.W., H.P., T.W. and U.R. commented on the manuscript.

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Correspondence to Philip F. Sexton.

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The authors declare no competing financial interests.

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Sexton, P., Norris, R., Wilson, P. et al. Eocene global warming events driven by ventilation of oceanic dissolved organic carbon. Nature 471, 349–352 (2011).

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