HR: 10:20h
AN: U22B-01 INVITED    [Abstracts]
TI: Annually resolved lake and shallow marine sediment records of global climate change of the past 16,000 years
AU: * Haug, G H
EM: gerald.haug@erdw.ethz.ch
AF: Geologiacl Institute, ETH Zurich, Universitaetsstr. 22, Zurich, 8092, Switzerland
AU: Brauer, A
EM: brau@gfz-potsdam.de
AF: GFZ Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Yancheva, G
EM: gergana@gfz-potsdam.de
AF: GFZ Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Dulski, P
EM: dulski@gfz-potsdam.de
AF: GFZ Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Negendank, J F
EM: neg@gfz-potsdam.de
AF: GFZ Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Peterson, L C
EM: lpeterson@rsmas.miami.edu
AF: RSMAS, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, United States
AU: Sigman, D M
EM: sigman@princeton.edu
AF: Geosciences, Princeton University, Guyot Hall, Princeton, NJ 08544, United States
AB: In the sediments of lake Huguang Maar in coastal southeast China, the titanium content and redox-sensitive magnetic properties record the strength of winter monsoon winds at subdecadal to annual resolution over the last 16 thousand years. The record indicates a stronger winter monsoon prior to the Bølling-Allerød warming, during the Younger Dryas, and during the middle and late Holocene, when cave stalagmite oxygen isotope data indicate a weaker summer monsoon. The anti-correlation between winter and summer monsoon strength is best explained by migrations in the ITCZ that occurred simultaneously in central America and Africa. Drought associated with southward ITCZ migration may have played a role in the termination of several Chinese dynasties. A remarkable similarity of ITCZ migration in east Asia and the Americas from 700 to 900 AD raises the possibility that the coincident declines of the important Tang Dynasty in China and the Classic Maya in Central America were catalyzed by the same ITCZ migrations. The mechanisms behind these decadal-scale ITCZ-monsoon swings can be further exoplored at major climate transitions such as the onset of Younger Dryas cooling at ~12.7 ka, one of the most abrupt climate changes observed in ice core, lake and marine records in the North Atlantic realm and much of the Northern Hemisphere. Annually laminated lake sediments ideally record the dynamics of abrupt climate changes since seasonal deposition immediately responds to climate and varve counts accurately estimate the time of change. We report new sub-annual geochemical and varve microfacies data from a lake in Western Germany, which provides one of the best-dated records currently available for this climate transition, which we compare to the Cariaco Basin and Lake Huguang Maar records. The Lake Meerfelder Maar record indicates an abrupt increase in storminess, occurring from one year to the next at 12,678 ka BP, coincident with other observed climate changes in the region. We interpret this shift of the wintertime winds to signify an abrupt change in the North Atlantic westerlies to a stronger and more zonal jet. Given that oceanic heat transport associated with North Atlantic meridional overturning, in its own right, does not appear to greatly impact European climate, the observed wind shift provides the atmospheric mechanism for the strong temporal link between North Atlantic overturning and European climate during the last deglaciation, tightly coupled to ITCZ migrations.
DE: 1000 GEOCHEMISTRY
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4901 Abrupt/rapid climate change (1605)
SC: Union [U]
MN: 2007 Fall Meeting