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Climate of the Past An interactive open-access journal of the European Geosciences Union
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Volume 11, issue 10 | Copyright

Special issue: Climatic and biotic events of the Paleogene

Clim. Past, 11, 1313-1324, 2015
https://doi.org/10.5194/cp-11-1313-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 07 Oct 2015

Research article | 07 Oct 2015

Frequency, magnitude and character of hyperthermal events at the onset of the Early Eocene Climatic Optimum

V. Lauretano1, K. Littler2,a, M. Polling1, J. C. Zachos2, and L. J. Lourens1 V. Lauretano et al.
  • 1Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Heidelberglaan 2, 3584 CS, Utrecht, the Netherlands
  • 2Department of Earth and Planetary Sciences, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
  • anow at: Camborne School of Mines, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK

Abstract. Recent studies have shown that the Early Eocene Climatic Optimum (EECO) was preceded by a series of short-lived global warming events, known as hyperthermals. Here we present high-resolution benthic stable carbon and oxygen isotope records from ODP Sites 1262 and 1263 (Walvis Ridge, SE Atlantic) between ~ 54 and ~ 52 million years ago, tightly constraining the character, timing, and magnitude of six prominent hyperthermal events. These events, which include Eocene Thermal Maximum (ETM) 2 and 3, are studied in relation to orbital forcing and long-term trends. Our findings reveal an almost linear relationship between δ13C and δ18O for all these hyperthermals, indicating that the eccentricity-paced covariance between deep-sea temperature changes and extreme perturbations in the exogenic carbon pool persisted during these events towards the onset of the EECO, in accordance with previous observations for the Paleocene Eocene Thermal Maximum (PETM) and ETM2. The covariance of δ13C and δ18O during H2 and I2, which are the second pulses of the "paired" hyperthermal events ETM2-H2 and I1-I2, deviates with respect to the other events. We hypothesize that this could relate to a relatively higher contribution of an isotopically heavier source of carbon, such as peat or permafrost, and/or to climate feedbacks/local changes in circulation. Finally, the δ18O records of the two sites show a systematic offset with on average 0.2 ‰ heavier values for the shallower Site 1263, which we link to a slightly heavier isotopic composition of the intermediate water mass reaching the northeastern flank of the Walvis Ridge compared to that of the deeper northwestern water mass at Site 1262.

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Several episodes of global warming took place during greenhouse conditions in the early Eocene and are recorded in deep-sea sediments. The stable carbon and oxygen isotope records are used to investigate the magnitude of six of these events describing their effects on the global carbon cycle and the associated temperature response. Findings indicate that these events share a common nature and hint to the presence of multiple sources of carbon release.
Several episodes of global warming took place during greenhouse conditions in the early Eocene...
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