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Pronounced zonal heterogeneity in Eocene southern high-latitude sea surface temperatures

Douglas, Peter M. J. and Affek, Hagit P. and Ivany, Linda C. and Houben, Alexander J. P. and Sijp, Willem P. and Sluijs, Appy and Schouten, Stefan and Pagani, Mark (2014) Pronounced zonal heterogeneity in Eocene southern high-latitude sea surface temperatures. Proceedings of the National Academy of Sciences of the United States of America, 111 (18). pp. 6582-6587. ISSN 0027-8424. PMCID PMC4020054.

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Paleoclimate studies suggest that increased global warmth during the Eocene epoch was greatly amplified at high latitudes, a state that climate models cannot fully reproduce. However, proxy estimates of Eocene near-Antarctic sea surface temperatures (SSTs) have produced widely divergent results at similar latitudes, with SSTs above 20 °C in the southwest Pacific contrasting with SSTs between 5 and 15 °C in the South Atlantic. Validation of this zonal temperature difference has been impeded by uncertainties inherent to the individual paleotemperature proxies applied at these sites. Here, we present multiproxy data from Seymour Island, near the Antarctic Peninsula, that provides well-constrained evidence for annual SSTs of 10–17 °C (1σ SD) during the middle and late Eocene. Comparison of the same paleotemperature proxy at Seymour Island and at the East Tasman Plateau indicate the presence of a large and consistent middle-to-late Eocene SST gradient of ∼7 °C between these two sites located at similar paleolatitudes. Intermediate-complexity climate model simulations suggest that enhanced oceanic heat transport in the South Pacific, driven by deep-water formation in the Ross Sea, was largely responsible for the observed SST gradient. These results indicate that very warm SSTs, in excess of 18 °C, did not extend uniformly across the Eocene southern high latitudes, and suggest that thermohaline circulation may partially control the distribution of high-latitude ocean temperatures in greenhouse climates. The pronounced zonal SST heterogeneity evident in the Eocene cautions against inferring past meridional temperature gradients using spatially limited data within given latitudinal bands.

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Additional Information:© 2014 National Academy of Sciences. Published online before print April 21, 2014. Edited by Mark H. Thiemens, University of California, San Diego, La Jolla, CA, and approved March 21, 2014 (received for review November 15, 2013). Gerard Olack, Dominic Colosi, and Glendon Hunsinger provided assistance with clumped isotope measurements; Shikma Zaarur provided advice on clumped isotope data analysis; Christy Visaggi, Michelle Casey, and Steven Roof provided modern bivalve samples; and Natasja Welters and Jan van Tongeren (Utrecht University) assisted with palynological preparations. We thank two anonymous reviewers for constructive commentary. This work was supported by US National Science Foundation Grants EAR-0842482 (to H.P.A.) and PLR-0125409 (to L.C.I.), and Statoil and European Research Council Starting Grant 259627 (to A.S.). Author contributions: P.M.J.D., H.P.A., and L.C.I. designed research; P.M.J.D., A.J.P.H., and W.P.S. performed research; P.M.J.D., H.P.A., L.C.I., A.J.P.H., W.P.S., A.S., S.S., and M.P. analyzed data; and P.M.J.D. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. This article contains supporting information online at
Funding AgencyGrant Number
European Research Council (ERC)259627
Subject Keywords:paleooceanography, clumped isotopes, organic geochemistry, climate modeling, high-latitude climate
Issue or Number:18
PubMed Central ID:PMC4020054
Record Number:CaltechAUTHORS:20140610-081905360
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Official Citation:Peter M. J. Douglas, Hagit P. Affek, Linda C. Ivany, Alexander J. P. Houben, Willem P. Sijp, Appy Sluijs, Stefan Schouten, and Mark Pagani Pronounced zonal heterogeneity in Eocene southern high-latitude sea surface temperatures PNAS 2014 111 (18) 6582-6587; published ahead of print April 21, 2014, doi:10.1073/pnas.1321441111
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46171
Deposited By: Ruth Sustaita
Deposited On:10 Jun 2014 17:37
Last Modified:03 Oct 2019 06:41

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