Mid-Pliocene shifts in ocean overturning circulation and the onset of Quaternary-style climates

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doi: 10.5194/cp-5-269-2009
Author(s): Sarnthein, Michael; Bartoli, Gretta; Prange, Matthias; Schmittner, Andreas; Schneider, Birgit; Weinelt, Mara; Andersen, Nils; Garbe-Schönberg, Dieter
Author Affiliation(s): Primary:
Universität Kiel, Institut für Geowissenschaften, Kiel, Federal Republic of Germany
University of Bremen, Federal Republic of Germany
Oregon State University, United States
Volume Title: Climate of the Past
Source: Climate of the Past, 5(2), p.269-283. Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1814-9324
Note: In English. Invited contribution by M. Sarnthein, recipient of the EGU Milutin Milankovic Medal 2006; part of the special issue No. 19, Climate change; from the geological past to the uncertain future - a symposium honouring Andre Berger, edited by Crucifix, M. et al., http://www.clim-past.net/special_issue19.html; published in Climate of the Past Discussion: 26 January 2009, http://www.clim-past-discuss.net/5/251/2009/cpd-5-251-2009.html; accessed in November, 2009. 58 refs.; illus., incl. sketch maps
Summary: A major tipping point of Earth's history occurred during the mid-Pliocene: the onset of major Northern-Hemisphere Glaciation (NHG) and of pronounced, Quaternary-style cycles of glacial-to-interglacial climates, that contrast with more uniform climates over most of the preceding Cenozoic and continue until today (Zachos et al., 2001). The severe deterioration of climate occurred in three steps between 3.2 Ma (warm MIS K3) and 2.7 Ma (glacial MIS G6/4) (Lisiecki and Raymo, 2005). Various models (sensu Driscoll and Haug, 1998) and paleoceanographic records (intercalibrated using orbital age control) suggest clear linkages between the onset of NHG and the three steps in the final closure of the Central American Seaways (CAS), deduced from rising salinity differences between Caribbean and the East Pacific. Each closing event led to an enhanced North Atlantic meridional overturning circulation and this strengthened the poleward transport of salt and heat (warmings of +2-3°C) (Bartoli et al., 2005). Also, the closing resulted in a slight rise in the poleward atmospheric moisture transport to northwestern Eurasia (Lunt et al., 2007), which probably led to an enhanced precipitation and fluvial run-off, lower sea surface salinity (SSS), and an increased sea-ice cover in the Arctic Ocean, hence promoting albedo and the build-up of continental ice sheets. Most important, new evidence shows that the closing of the CAS led to greater steric height of the North Pacific and thus doubled the low-saline Arctic Throughflow from the Bering Strait to the East Greenland Current (EGC). Accordingly, Labrador Sea IODP Site 1307 displays an abrupt but irreversible EGC cooling of 6°C and freshening by ∼2 psu from 3.25/3.16-3.00 Ma, right after the first but still reversible attempt of closing the CAS.
Year of Publication: 2009
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Arctic Ocean; Arctic region; Atlantic Ocean; Atmospheric circulation; Bering Strait; Carbon dioxide; Caribbean Sea; Cenozoic; Climate change; Climate forcing; Cocos Ridge; Colombian Basin; East Pacific; Equatorial Pacific; Eurasia; Expeditions 303/306; Fram Strait; Glacial environment; Glacial geology; Global change; Global warming; Greenland; Greenland ice sheet; IODP Site U1307; Ice; Ice sheets; Integrated Ocean Drilling Program; Interglacial environment; Labrador Sea; Leg 162; Leg 165; Leg 202; MIS 3; MIS 6; Middle Pliocene; Neogene; North Atlantic; Northern Hemisphere; Northwest Atlantic; ODP Site 1241; ODP Site 984; ODP Site 999; Ocean Drilling Program; Pacific Ocean; Paleo-oceanography; Paleocirculation; Paleoclimatology; Paleosalinity; Pliocene; Reykjanes Ridge; Sea ice; Tertiary
Coordinates: N612532 N612532 W0240457 W0240457
N124437 N124437 W0784422 W0784422
N583000 N583000 W0462400 W0462400
Record ID: 2010017099
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Copernicus Gesellschaft, Katlenburg-Lindau, Germany