HR: 09:30h
AN: PP41F-07    [Abstracts]
TI: Antarctic Climate-Cryosphere Response to Extreme Orbital Forcing During Marine Isotope Stage 31
AU: * DeConto, R
EM: deconto@geo.umass.edu
AF: Dept. of Geosciences, University of Massachusetts, Amherst, MA 01003, United States
AU: Pollard, D
EM: pollard@essc.psu.edu
AF: Earth and Environmental Systems Institute, Penn State University, University Park, PA 16802, United States
AU: Scherer, R
EM: T60RPS1@wpo.cso.niu.edu
AF: Dept. of Geology and Environmental Geosciences, Northern Illinois University, DeKalb, IL 60115, United States
AU: Powell, R
EM: ross@geol.niu.edu
AF: Dept. of Geology and Environmental Geosciences, Northern Illinois University, DeKalb, IL 60115, United States
AU: Naish, T
EM: t.naish@gns.cri.nz
AF: GNS Science, PO Box 30368, Lower Hutt, 5040, New Zealand
AB: Sedimentary records from the Antarctic Margin and Southern Ocean suggest MIS-31 was several degrees warmer than today in high southern latitudes, with evidence of open water in the Ross Sea coeval with an orbital configuration producing anomalously warm austral summers ~1.082 Ma (Scherer et al., submitted). The lack of a buttressing ice shelf during MIS-31 and perhaps other periods of Southern Hemisphere summer warmth has important implications for the ice streams that drain Antarctic Ice Sheets into the Ross Sea. Here, we test the response of the Antarctic climate-cryosphere system (with an emphasis on the Ross Ice Shelf and West Antarctic Ice Sheet) to MIS-31 orbital forcing, using a coupled GCM-ice sheet model with extensions including explicit representations of the coupled sheet-shelf-sediment system and grounding lines. GCM simulations of MIS-31 have already shown that orbital forcing alone (in the absence of CO2 feedback) is capable of raising mean annual surface temperatures by 2-5 deg. C around the Antarctic margin. The simulated (possibly nonlinear) response of grounding lines and the West Antarctic Ice Sheet to warmer sea surface temperatures, the loss of the Ross Ice Shelf, and rising sea levels are compared with well-dated proximal records of MIS-31 from the Ross Sea obtained by the Cape Roberts Project and ANDRILL sedimentary drilling programs.
DE: 0726 Ice sheets
DE: 0728 Ice shelves
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4910 Astronomical forcing
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting