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www.clim-past-discuss.net/7/965/2011/
doi:10.5194/cpd-7-965-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
Tropical seaways played a more important role than high latitude seaways in Cenozoic cooling
1Bjerknes Centre for Climate Research, UniResearch, 5007 Bergen, Norway
2Nansen-Zhu International Research Center, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029 Beijing, China
3Nansen Environmental and Remote Sensing Center, 5006 Bergen, Norway
Abstract. Following the Early Eocene climatic optimum (EECO, ~55–50 Ma), climate deteriorated and gradually changed the earth from a greenhouse into an icehouse, with major cooling events at the Eocene-Oligocene boundary (~34 Ma) and the Middle Miocene (~15 Ma). It is believed that the opening of the Drake Passage had a marked impact on the cooling at the Eocene-Oligocene boundary. Based on an Early Eocene simulation, we study the sensitivity of climate and ocean circulation to the tectonic events such as the closing of the West Siberian Seaway, the deepening of the Arctic-Atlantic Seaway, the opening of the Drake Passage, and the constriction of the Tethys and Central American seaways. The opening of the Drake Passage, together with the closing of the West Siberian Seaway, and the deepening of the Arctic-Atlantic Seaway, weakens the Southern Ocean Deep Water (SODW) dominated ocean circulation and leads to a weak cooling at high latitudes, thus contributing to the observed Early Cenozoic cooling. However, the later constriction of the Tethys and Central American Seaways is shown to give a strong cooling at southern high latitudes. This cooling is related to the transition of ocean circulation from a SODW-dominated mode to the modern-like ocean circulation dominated by North Atlantic Deep Water (NADW).
Discussion Paper (PDF, 2542 KB) Supplement (788 KB) Interactive Discussion (Closed, 7 Comments) Final Revised Paper (CP)
Notice on Discussion StatusCitation: Zhang, Z., Nisancioglu, K. H., Flatøy, F., Bentsen, M., Bethke, I., and Wang, H.: Tropical seaways played a more important role than high latitude seaways in Cenozoic cooling, Clim. Past Discuss., 7, 965-996, doi:10.5194/cpd-7-965-2011, 2011. Bibtex EndNote Reference Manager XML
