HR: 1340h
AN: PP33B-1560    [Abstracts]
TI: Millennial-scale climate cycles through the Holocene: A global, synchronous phenomenon?
AU: * Turney, C
EM: turney@uow.edu.au
AF: GeoQuEST Research Centre, School of Earth and Environmental Science, University of Wollongong, Northfields Ave, Wollongong, NSW 2522 Australia
AU: McGlone, M
EM: McGloneM@landcareresearch.co.nz
AF: Landcare Research, PO Box 64, Lincoln, 8152 New Zealand
AU: Wilmshurst, J
EM: WilmshurstJ@landcareresearch.co.nz
AF: Landcare Research, PO Box 64, Lincoln, 8152 New Zealand
AB: The present interglacial was until recently considered to be a period of exceptional climatic stability. Changes in the concentration of lithic grains through Holocene North Atlantic sediments, however, have now been shown to represent pervasive 900 and 500 yr cycles (loosely bundled together as a quasi-periodic `1500 yr' cycle), recording the southward advection of cold, ice bearing waters from the Labrador and Nordic Seas. Similar quasi-cycles have now been recorded throughout the Northern Hemisphere, consistent with Dansgaard Oeschger oscillations, suggesting a climate pacemaker, independent of glacial interglacial cycles and anthropogenic forcing. Antarctic ice core isotopic records provide strong evidence that this cyclicity is also present at high-ªlatitudes in the Southern Hemisphere, supporting the contention that the changes are related to the strength of the thermohaline circulation and suggesting such events may be global in extent. To test this hypothesis, we have investigated six high-resolution Holocene sequences on a transect in the Southern Ocean that straddle important present-day climatic boundaries. Over 70 radiocarbon ages were obtained through the six sequences and calibrated using the Bayesian method option on the OxCal radiocarbon calibration program. Ages for the Subantarctic islands were complemented by changes in `long-distance' pollen derived from the New Zealand mainland. Quasi-cyclic variations in surface moisture are recorded throughout the Holocene in many of the sequences. The wider implications of these results with regards millennial-scale climate change will be discussed.
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005