HR: 13:40h
AN: C13A-01 INVITED    [Abstracts]
TI: The Greenland ice Sheet Since LGM, an Overview.
AU: * Funder, S
EM: svf@snm.ku.dk
AF: Geological Museum, University of Copenhagen, Oster Voldgade 5-7, Copenhagen, DK- 1350, Denmark
AB: During LGM (last glacial maximum) the Greenland ice sheet covered an area of c. 3 mio km2, 40% more than now. This appears from a compilation of geological and geophysical studies on land and on the shelf. Ice sheet break up began at c. 15 ka with the clearance of the shelves, c. 0.8 mio km2. This may have been triggered by sea level rise, and was followed by melting and calving of ice on land in the Early Holocene. However, only c. 0.4 mio km2 of land and fjords were cleared of ice during this period of optimal warmth - an indication of the ice sheet's remarkable stability. In view of ice sheet response to future greenhouse warming, this phase of deglaciation is especially interesting. Recent field work in different parts of Greenland and a compilation of curves for isostatic emergence have shown that timing, amount, and rate of change varied from area to area. This is due not only to differences in local climate, but also to local topography, capacity of drainage ways (fjords and shelf-troughs), and presence or absence of ice streams. Before 7.5 ka the present state of glaciation had been attained in most parts. After this, the margins withdrew behind their present location, possibly as much as 40 km in some areas. Pollen and other climate proxies show that cooling and Neoglacial readvance of the ice margin began at c. 5.5 ka. This culminated around 1920 when glaciers in most parts began rapid retreat. Even though this retreat in most areas amounted to a few kilometres at most, it is more significant than the retreat in "greenhouse times".
DE: 0726 Ice sheets
DE: 1105 Quaternary geochronology
SC: Cryosphere [C]
MN: 2007 Fall Meeting