Greenland glacial history, borehole constraints, and Eemian extent

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. B3, 2143, doi:10.1029/2001JB001731, 2003

Department of Physics, University of Toronto,
Toronto, Ontario, Canada

Abstract

[1] We examine the extent to which observations from the Greenland ice sheet combined with three-dimensional dynamical ice sheet models and semi-Lagrangian tracer methods can be used to constrain inferences of the Eemian evolution of the ice sheet, of the extent and frequency of summit migration during the 100 kyr ice age cycle, and of the deep geothermal flux of heat from the Earth into the base of the ice sheet. Relative sea level, present-day surface geometry, basal temperature, and age and temperature profiles from the Greenland Ice Project (GRIP) are imposed as constraints to tune ice sheet model and climate forcing parameters. Despite the paucity of observations, model-based inferences suggest a significant northeast gradient in geothermal heat flux. Our analyses also suggest that during the glacial cycle, the contemporaneous summit only occupied the present-day location during interglacial periods. On the basis of the development and use of a high-resolution semi-Lagrangian tracer analysis methodology for delta ¹⁸O, we rule out isotropic flow disturbances due to summit migration as a possible source of the high Eemian variability of the GRIP delta ¹⁸O record. Finally, in contrast with results obtained in some recent attempts to infer the extent to which Greenland may have contributed to the anomalous highstand of Eemian sea level, we find that conservative bounds for this contribution are 2–5.2 m, with a more likely range of 2.7–4.5 m.

Received 20 December 2001; revised 12 September 2002; accepted 4 October 2002; published 12 March 2003.

Keywords: Greenland ice sheet, Eemian, semi-Lagrangian tracer, geothermal heat flux, GRIP ice core, relative sea level.

Index Terms: 1827 Hydrology: Glaciology (1863); 1863 Hydrology: Snow and ice (1827); 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology; 9315 Information Related to Geographic Region: Arctic region.

Citation: Tarasov, L., and W. R. Peltier, Greenland glacial history, borehole constraints, and Eemian extent, J. Geophys. Res., 108(B3), 2143, doi:10.1029/2001JB001731, 2003.