Tropical Pacific Hydrologic Changes During the Last 1,000 Years from Lipid D/H Ratios in Lake and Ocean Sediments

HR: 16:00h
AN: PP34A-01 INVITED [Abstracts]
TI: Tropical Pacific Hydrologic Changes During the Last 1,000 Years from Lipid D/H Ratios in Lake and Ocean Sediments
AU: * Sachs, J P
EM: jsachs@u.washington.edu
AF: University of Washington, School of Oceanography, Box 355351, Seattle, WA 98195, United States
AU: Sachse, D
EM: dsachse@u.washington.edu
AF: University of Washington, School of Oceanography, Box 355351, Seattle, WA 98195, United States
AU: Zhang, Z
EM: zhaohui@nsm.umass.edu
AF: University of Massachusetts, Department of Geosciences, 611 North Pleasant Street, Amherst, MA 01003, United States
AU: Smittenberg, R
EM: smittenberg@erdw.ethz.ch
AF: University of Washington, School of Oceanography, Box 355351, Seattle, WA 98195, United States
AB: The climate of the last millennium was punctuated by two prominent events: the Medieval Warm Period (MWP) from 800-1300 A.D. and the Little Ice Age (LIA) from 1400-1850. The impact of, and evidence for these events derives almost exclusively from the middle latitudes of the Northern Hemisphere continents, largely from tree rings and mountain glaciers. Remarkably little attention has been given to the tropical climate of the last millennium and its potential impact on the middle and high latitudes even though massive fluxes of latent heat, moisture and momentum derive from there. Indeed, proxy records of the ENSO system, the monsoons of Asia and India, and the position of the Intertropical Convergence Zone (ITCZ) indicate that the last 1,000 years were a time of profound change in the tropical climate globally. Here we present evidence from D/H ratios in lipids from lake and ocean sediments in the western, central and eastern tropical Pacific that the LIA was a time of marked change in rainfall patterns. Specifically, our data (1) strongly imply that the ITCZ was poleward of 5 degrees north latitude for at least 2,500 years prior to 1600 A.D., and (2) are consistent with a frequency and/or intensity of El Niño that was high during the Little Ice Age compared to the rest of the last millennium.
DE: 0420 Biomolecular and chemical tracers
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4522 ENSO (4922)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting