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au=marchant

HR: 09:00h
AN: C51C-05
TI: Sensitivity of Ice-Rich Antarctic Slopes to Climate Change: Are Terrestrial Archives at Risk?
AU: * Swanger, K M
EM: kswanger@bu.edu
AF: Boston University, Department of Earth Sciences, 675 Commonwealth Avenue, Boston, MA 02215, United States
AU: Marchant, D R
EM: marchant@bu.edu
AF: Boston University, Department of Earth Sciences, 675 Commonwealth Avenue, Boston, MA 02215, United States
AB: We modeled the sensitivity of ice-rich slope deposits from the western McMurdo Dry Valleys, Antarctica to failure by shallow, thaw-induced planar sliding. The deposits examined have purportedly remained physically stable, without morphologic evidence for downslope movement, for millions of years. Could they fail in the near future from greenhouse-induced warming? To address this question, we first prescribed various increases in mean summertime soil surface temperature (MSSST) and modeled numerically the resultant changes in soil thaw depths using a one-dimensional heat diffusion equation. Second, we calculated the minimum thaw depths required to facilitate failure by shallow planar sliding for each deposit; for all numerical simulations, we maintained present soil-moisture conditions and used a Mohr-Coulomb-based equation of safety factor. Third, we calculated the flow rate of subsurface meltwater assuming Darcy's Law. Our results show that some ice-rich slopes could fail if MSSST, and by inference mean summertime atmospheric temperatures, increase by 5 to 9 C. If we assume that physical evidence for shallow planar slides would be retained in the geomorphic record, and that current soil-moisture conditions can be applied to slope deposits in the distant past (i.e., millions of years ago), then our results suggest that since late Miocene time (the age of the youngest deposits examined) atmospheric temperatures could not have increased by more than 5 to 9 C above present values.
DE: 0710 Periglacial processes
DE: 0768 Thermal regime
DE: 0798 Modeling
DE: 1810 Debris flow and landslides
SC: Cryosphere [C]
MN: 2007 Fall Meeting


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