HR: 16:00h
AN: PP32D-01 INVITED     [PDF]
TI: Modeling of the Early Cenozoic History of the Antarctic Ice Sheet
AU: * Pollard, D
EM: pollard@essc.psu.edu
AF: Pennsylvania State University, Environment Institute, 2217 Earth and Engineering Sciences Building, Pennsylvania State University, University Park, PA 16802 United States
AU: DeConto, R M
AF: University of Massachusetts, Department of Geosciences, 233 Morrill Science Center University of Massachusetts, Amherst, MA 01003 United States
AB: Numerical modeling of the initial growth of the Antarctic Ice Sheet in the Paleogene using coupled climate-ice sheet-sediment components is reviewed. In this approach, a Global Climate Model (GCM) is asynchronously coupled to a dynamical 3-D Antarctic ice sheet-sediment model, to test the sensitivity of the coupled system to evolving Cenozoic boundary conditions, including paleogeography, atmospheric carbon dioxide, changing orbital parameters, and changes in ocean heat transport. The asynchronous coupling scheme enables long (millions of years) integrations, simulating ice sheet inception around the Eocene-Oligocene boundary, and subsequent ice sheet variability over orbital timescales. It is found that declining Cenozoic atmospheric carbon dioxide and relatively high frequency orbital forcing trigger ice-sheet height-mass balance feedbacks that produce a sudden transition, from relatively small land-based ice caps localized on high topography, to a single large East Antarctic ice sheet comparable to today, similar to observed events around the Eocene-Oligocene boundary. Changes in ocean heat transport, like those assumed to have occurred in response to the opening of Southern Ocean gateways (Tasmanian and Drake Passages) are shown to have a smaller effect than previously expected. The consequences of hysteresis due to the height-mass balance feedback, the relation to albedo feedback and the stability of the East Antarctic Ice Sheet are discussed. Predicted spatial and temporal patterns of coastal sediment discharge are compared with observed distributions and core records of offshore Cenozoic sedimentary deposits.
DE: 1620 Climate dynamics (3309)
DE: 1827 Glaciology (1863)
DE: 9310 Antarctica
DE: 9604 Cenozoic
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting