HR: 17:15h
AN: GC44A-06    [Abstracts]
TI: Glaciers in Equilibrium - Results from the McMurdo Dry Valleys, Antarctica
AU: * Fountain, A G
EM: andrew@pdx.edu
AF: Department of Geology Portland State University, 1721 SW Broadway, Portland, OR 97212 United States
AU: Nylen, T H
EM: nylent@pdx.edu
AF: Department of Geology Portland State University, 1721 SW Broadway, Portland, OR 97212 United States
AU: Doran, P T
EM: pdoran@uic.edu
AF: Department of Earth and Environmental Sciences University of Illinois at Chicago, 845 West Taylor Street, Chicago, IL 60607 United States
AB: Since 1993 the mass balance of two glaciers in the McMurdo Dry Valleys, Antarctica ($163\deg$E $77.5\deg$S) has been measured. The magnitude of annual mass gain or loss does not exceed 10 cm water equivalent averaged over each glacier, consistent with the local climate of a polar desert. The overall trend in mass balance shows that the glaciers are in approximate balance with the current climate and no obvious trends exist in either the winter or summer balances. These are similar to a set of mass balance measurements made in another part of the dry valleys during the 1970s (Chinn, 1985). Recent analysis of the climate of the dry valleys shows this region is cooling at a rate of $0.7\deg$C per decade during this period since 1986, which is reflected in the overall lowering of lake levels, decreased primary productivity of the lakes, and declining number of invertebrates (Doran et al., 2002). Although an unusually warm period occurred in the summer of 2001-2002, annual temperatures continue to cool. This region seems to be isolated from the warming elsewhere in Antarctica and the cooling in this part of the Ross Sea region may be due to El Nino forcing (Bertler et al, 2004). The sluggish behavior of the glaciers results from a low mass exchange and an apparent climatic buffering, which supports evidence from the geologic record that these glaciers have not advanced more than a few hundred meters over the past 3 million years (Hall et al., 1993). Many of the glaciers, however, are advancing which probably results from a slow time-scale response from warming conditions in the past millennium.
DE: 1655 Water cycles (1836)
DE: 1827 Glaciology (1863)
DE: 1860 Runoff and streamflow
DE: 1863 Snow and ice (1827)
SC: Global Climate Change [GC]
MN: 2004 AGU Fall Meeting