Recent fluctuations of the Dry Valleys glaciers, McMurdo Sound, Antarctica

Abstract

The state of equilibrium of the frontal positions of the glaciers of the Dry Valleys area of McMurdo Sound, Antarctica, has been a subject of speculation since they were first seen. A programme to measure the changes in frontal positions of 12 ice-cliffed glaciers has been maintained since 1982-83, with a 30 year record for Meserve Glacier. Simple taped distances from fixed points to the fronts of the glaciers have demonstrated that, in proportion to their flow and ablation regimes which are two orders of magnitude slower than those of temperate glaciers, the glaciers are fluctuating as dynamically as do temperate glaciers. Maximum advance or recession rates have been found to be near ± 1 m a-1, changes which are almost undetectable in comparative photographs. Recession was found to be the dominant change trend, with yearly variations reflecting changes in annual ablation. The total height of the ice cliff gives a ready estimation of glacier equilibrium, with cliff heights being greatest on advancing glaciers. The division between advancing and receding glaciers was found to be at a cliff height of about 25 m.