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Inland Ice Sheet Thinning due to Holocene Warmth

Published online by Cambridge University Press:  30 January 2017

I. M. Whillans
I. M. Whillans*
Affiliation:
Institute of Polar Studies and Department of Geology and Mineralogy, Ohio State University, Columbus, Ohio 43210, U.S.A.
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Abstract

The Holocene warmth is now affecting the flow of the central West Antarctic ice sheet. It is supposed that the ice sheet reached approximate steady-state during the Wisconsinan. A perturbation analysis of ice-sheet temperatures indicates that deep ice has warmed by one or two degrees since the Wisconsinan. Warmer ice deforms more rapidly and the ice sheet should now be flowing 10 to 30% faster than during the Wisconsinan.

Type
Abstracts of Papers Presented at the Symposium but not Published in Full in this volume
Information
Journal of Glaciology , Volume 24 , Issue 90 , 1979 , pp. 484
Copyright
Copyright © International Glaciological Society 1979

Earlier studies comparing ice outflow with the replenishment by new snow accumulation show that the velocities are about 20% faster than those needed to balance the accumulation. The warming effect is therefore a sufficient explanation for the imbalance and it is not necessary to suggest that there were also changes in accumulation-rate or in sea-level that affected this part of the ice sheet.

The increased ice outflow resulting from the warming, propagates down-glacier and causes marginal thickening and advance. In the case of the Laurentide and Scandinavian ice sheets, a major increase in net ablation and a decrease in total ice volume is expected, by this mechanism, to lag behind a climatic warming by many thousands of years.

The paper has been published in full in Science, Vol. 201, No. 4360, 1978, p. 1014–16.

Discussion

D. A. Yuen [written question]: Your analysis of the effect on the velocity of ice sheets due to sudden perturbation of surficial temperature does not include the feed-back of the u .∇T term on the resultant energy equation. In a stability analysis, where dynamical effects are included, the effects of the temperature and velocity on one another are fully coupled, and must be solved in a fully self-consistent manner. How do you make a posteriori estimates of the perturbed velocity field from your approach?

I. M. Whillans: I am concerned here only with the first effects of the warming on ice flow. Calculations of later effects should include this feed-back.