Dynamics of the Greenland Ice SheetICE CORES, Elsevier, p. 1288-1296, 2007
C.S. Hvidberg, A. Svensson and S.L. Buchardt
Ice and Climate, The Niels Bohr Institute, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark
The Greenland ice sheet is the largest ice sheet in the Northern Hemisphere (Fig. 1). Although its volume is only about one-tenth of the ice sheets of Antarctica, it accounts for the remaining 50 % of Earth's freshwater resources.
During the Quaternary period, alternating glacial and interglacial periods caused intervals of ice-sheet growth and decay in the Northern Hemisphere. During the Last Glacial Maximum (20 ka BP), the Northern Hemisphere ice sheets were at their maximum, with large ice sheets in North America (Laurentide ice sheet), in Greenland, and in Northern Europe (Fennoscandian ice sheet). Of these, only the Greenland ice sheet remains today.
This is thought to be mainly due to the proximity of the Greenland ice sheet to the Atlantic Ocean, which strongly affects the climate in Greenland and provides ample supplies of precipitation. Weather systems traveling northeast across the North Atlantic carry moisture to the Greenland ice sheet. Precipitation rates in central Greenland are of the order of tens of centimeters of water equivalent per year, about ten times the annual accumulation in East Antarctica (e.g. van der Veen (1999)).
The Greenland ice sheet plays an important role in climate research because of its location. The ice sheet interacts dynamically with the atmosphere and ocean in the North Atlantic, which is a region thought to play a key role in global climate changes. The ice sheet contains a unique archive of past climate changes, and ice that is more than 100 kyr old has been recovered in deep ice cores drilled through the Greenland ice sheet (NorthGRIP Members, 2004). Because snow accumulation rates in the central areas have been sufficiently high, annual layers may be resolved far back into the last glacial period (Svensson et al., 2005). Ice-sheet flow and annual layers observed in ice cores have thinned and stretched since they were originally deposited as surface snow. Understanding the dynamics of the Greenland ice sheet is crucial for interpretation of the climate information stored in the ice, and for understanding the dynamical response of the ice sheet to climate change.