1. Palaeoecology, Institute of Environmental Biology, Utrecht University, Laboratory of Palaeobotany and Palynology,
2. Department of Earth Sciences, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, The Netherlands
3. Royal Netherlands Institute for Sea Research (NIOZ), Department of Marine Biogeochemistry and Toxicology, PO Box 59, 1790 AB, Den Burg, Texel, The Netherlands
4. Earth Sciences Department, University of California Santa Cruz, Santa Cruz, California 95060, USA
5. Department of Earth Sciences, Rice University, 6100 Main Street, Houston, Texas 77005, USA
6. Present addresses: Integrated Ocean Drilling Program, Texas A&M University, 1000 Discovery Drive, College Station, Texas 77845, USA (C.M.J.); GNS Science, PO Box 30-368, Lower Hutt, New Zealand (E.M.C.).

Correspondence to: Appy Sluijs¹ Correspondence and requests for materials should be addressed to A.S. (Email: A.Sluijs@uu.nl).

Abstract

The start of the Palaeocene/Eocene thermal maximum—a period of exceptional global warming about 55 million years ago—is marked by a prominent negative carbon isotope excursion that reflects a massive input of ¹³C-depleted ('light') carbon to the ocean–atmosphere system¹. It is often assumed² that this carbon injection initiated the rapid increase in global surface temperatures and environmental change that characterize the climate perturbation^{3, 4, 5, 6, 7}, but the exact sequence of events remains uncertain. Here we present chemical and biotic records of environmental change across the Palaeocene/Eocene boundary from two sediment sections in New Jersey that have high sediment accumulation rates. We show that the onsets of environmental change (as recorded by the abundant occurrence ('acme') of the dinoflagellate cyst Apectodinium) and of surface-ocean warming (as evidenced by the palaeothermometer TEX₈₆) preceded the light carbon injection by several thousand years. The onset of the Apectodinium acme also precedes the carbon isotope excursion in sections from the southwest Pacific Ocean⁸ and the North Sea, indicating that the early onset of environmental change was not confined to the New Jersey shelf. The lag of 3,000 years between the onset of warming in New Jersey shelf waters and the carbon isotope excursion is consistent with the hypothesis that bottom water warming caused the injection of ¹³C-depleted carbon by triggering the dissociation of submarine methane hydrates^{1, 9, 10}, but the cause of the early warming remains uncertain.

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