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Climate of the Past An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/cp-2017-76
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
20 Jun 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Climate of the Past (CP).
Tropical Atlantic Climate and Ecosystem Regime Shifts during the Paleocene-Eocene Thermal Maximum
Joost Frieling1, Gert-Jan Reichart2,3, Jack J. Middelburg2, Ursula Röhl4, Thomas Westerhold4, Steven Bohaty5, and Appy Sluijs1 1Marine Palynology and Paleoceanography, Laboratory of Palaeobotany and Palynology, Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Heidelberglaan 2, 3584CS Utrecht, Netherlands
2Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Princetonplein 9, 3584CC Utrecht, Netherlands
3NIOZ Royal Netherlands Institute for Sea Research, 1790AB Den Burg, Texel, Netherlands
4MARUM, Leobener Straße 8, 28359, Bremen, Germany
5Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus European Way Southampton, SO14 3ZH United Kingdom
Abstract. The Paleocene – Eocene Thermal Maximum (PETM; 56 Ma) was a phase of rapid global warming associated with massive carbon input into the ocean-atmosphere system from a 13C-depleted reservoir. Many mid- and high-latitude sections have been studied and document changes in salinity, hydrology and sedimentation, deoxygenation, biotic overturning and migrations, but detailed records from tropical regions are lacking. Here, we study the PETM at Ocean Drilling Program (ODP) Site 959 in the equatorial Atlantic using a range of organic and inorganic proxies and couple these with dinoflagellate cyst (dinocyst) assemblage analysis. The PETM at Site 959 was previously found to be marked by a ~3.8 ‰ negative carbon isotope excursion (CIE), and a ~4 ºC surface ocean warming from the uppermost Paleocene to peak PETM, of which ~1 ºC occurs before the onset of the CIE. We record upper Paleocene dinocyst assemblages that are similar to PETM assemblages as found in extra-tropical regions, confirming poleward migrations of ecosystems during the PETM. The early stages of the PETM are marked by a typical acme of the tropical genus Apectodinium, which reaches abundances of up to 95 %. Subsequently, dinocyst abundances diminish greatly, as do carbonate and pyritized silicate microfossils. The combined paleoenvironmental information from Site 959 and a close by shelf site in Nigeria implies the general absence of eukaryotic surface-dwelling microplankton during peak PETM warmth is most likely caused by heat stress. Crucially, abundant organic benthic foraminiferal linings imply sustained export production, likely driven by prokaryotes. In sharp contrast, the recovery of the CIE yields rapid (≪10 kyr) fluctuations in the abundance of several dinocyst groups, suggesting extreme ecosystem and environmental variability.

Citation: Frieling, J., Reichart, G.-J., Middelburg, J. J., Röhl, U., Westerhold, T., Bohaty, S., and Sluijs, A.: Tropical Atlantic Climate and Ecosystem Regime Shifts during the Paleocene-Eocene Thermal Maximum, Clim. Past Discuss., https://doi.org/10.5194/cp-2017-76, in review, 2017.
Joost Frieling et al.
Joost Frieling et al.
Joost Frieling et al.

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Short summary
Past periods of global warming, such as the Paleocene-Eocene Thermal Maximum (PETM), are used to study biotic response to climate change. We show peak PETM temperatures in the tropical Atlantic (~37 ºC) caused heat-stress in several marine plankton groups. However, only slightly cooler temperatures afterwards allowed highly diverse plankton communities to bloom. This shows tropical plankton communities may be vulnerable to extreme warming, but may also recover rapidly.
Past periods of global warming, such as the Paleocene-Eocene Thermal Maximum (PETM), are used to...
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