HR: 16:45h
AN: PP34B-04    [Abstracts]
TI: Cooling of the Eastern Tropical North Pacific in Response to a Slow-Down of the Atlantic Meridional Overturning Circulation
AU: * Kienast, M
EM: markus.kienast@dal.ca
AF: Dept. Oceanography, Dalhousie University, 1355 Oxford Street, Halifax, NS B3H 4J1 Canada
AU: Kienast, S
EM: skienast@whoi.edu
AF: Dept. Oceanography, Dalhousie University, 1355 Oxford Street, Halifax, NS B3H 4J1 Canada
AU: Calvert, S E
EM: calvert@eos.ubc.ca
AF: Dept. Earth and Ocean Science, University of British Columbia, 6270 Univ. Blvd., Vancouver, BC V6T 1Z4 Canada
AU: Eglinton, T I
EM: teglinton@whoi.edu
AF: Dept. Marine Chemsistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 United States
AU: Mollenhauer, G
EM: gmollenhauer@whoi.edu
AF: Dept. Marine Chemsistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 United States
AU: Francois, R
EM: francois@eos.ubc.ca
AF: Dept. Earth and Ocean Science, University of British Columbia, 6270 Univ. Blvd., Vancouver, BC V6T 1Z4 Canada
AU: Francois, R
EM: francois@eos.ubc.ca
AF: Dept. Marine Chemsistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 United States
AU: Mix, A
EM: mix@coas.oregonstate.edu
AF: College of Ocean and Atmospheric Sciences, Oregon State University, COAS Admin. Bldg. 104, Corvallis, OR 97331 United States
AB: Surface ocean conditions in the Pacific Ocean, and in particular in the equatorial Pacific, during millennial-scale climate change in the past are intensely debated because they might hold the clue to whether abrupt global climate change has its origin there, or whether it is controlled by changes in the vigour of the Atlantic meridional overturning circulation (AMOC). A high-resolution alkenone unsaturation-based SST record from the eastern tropical Pacific north of the equator shows a cooling of ca. 1°C during the last glacial-interglacial transition, which is synchronous (within the recognized uncertainties of radiocarbon chronologies) with Heinrich event 1 in the North Atlantic. This cold spell is paralleled by a maximum in surface ocean productivity as inferred from 230-Th normalized organic carbon fluxes, suggesting that it was caused by increased upwelling. The observed cooling of the ETNP during the time interval of H1 is consistent with a southward displacement of the ITCZ caused by a slowdown of the AMOC during this event, but is at odds with model predictions about the occurrence of ENSO shutdowns (La Niña-like conditions) in the past. The records presented here thus lend strong support to the hypothesis that millennial-scale climate change is driven by a reorganization of the ocean's thermohaline circulation, albeit potentially amplified by tropical ocean-atmosphere interactions.
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 4522 ENSO (4922)
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4954 Sea surface temperature
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005