HR: 08:00h
AN: C11B-01 INVITED     [Abstracts]
TI: Is There a Record of a Northern Hemisphere Source for Meltwater Pulse 1A?
AU: * Clark, P U
EM: clarkp@onid.orst.edu
AF: Dept. Geosciences, Oregon State Univ., Corvallis, OR 97331
AB: Two primary sources of meltwater pulse 1A (MWP-1A) ~14,500 calendar years ago have been proposed: one largely from Northern Hemisphere ice sheets, and one largely from the Antarctic Ice Sheet. Here I summarize the well-dated record of deglaciation of Northern Hemisphere ice sheets around the time of MWP-1A to demonstrate that ice-margin retreat did not accelerate at that time. Accordingly, if MWP-1A did originate from remaining Northern Hemisphere ice sheets, deglaciation must have occurred by ~30 per cent ice-mass loss with little ice-margin retreat, indicating substantial ice-surface lowering and attendant relative rise of the equilibrium line. Near-contemporaneous abrupt warming at the onset of the Bolling-Allerod warm interval would further raise the equilibrium line. These combined effects would leave the contributing ice sheets far out of equilibrium with climate, yet ice-margin and sea-level records demonstrate that deglaciation progressed relatively uniformly for an additional 8500 years. Additional records of Northern Hemisphere deglaciation during this interval will also be discussed.
DE: 1827 Glaciology (0736, 0776, 1863)
DE: 3344 Paleoclimatology (0473, 4900)
SC: Cryosphere [C]
MN: Fall Meeting 2005