Antarctic Glaciers Accelerate in Wake of Ice Shelf Breakup:
Hektoria Glacier System (Hektoria, Green, and Evans Glaciers)
Landsat 7 Image Time Series
These Landsat 7 satellite images of this glacier system illustrate the ice shelf and glacier interactions explained in why glaciers accelerate.
In all images, the black contour line indicates the grounding line for the Larsen B Ice Shelf and the red arrow indicates the flow of the Hektoria Glacier system. (Images supplied by Ted Scambos and Jennifer Bohlander, NSIDC)
Click here for a higher-resolution image.
27 January 2000: The Hektoria Glacier system is stable, but increased summer melting from climate warming in the 1980s and 1990s affected the glacier system in two ways: (1) a seasonal speedup from summer melt water percolating through the glacier ice to its base, and (2) initial retreat of the Larsen Ice Shelf due to the effects of melt ponds (downstream from this image).
6 April 2002: Record-high temperatures and melting in the austral summer earlier this year caused significant glacier acceleration. While the March 2002 Larsen Ice Shelf disintegration likely resulted from rapid local climate warming, sea level is not affected by the breakup of ice that is already afloat.
18 December 2002: As ice shelf retreat continues past the grounding line, the lower portion of the glacier accelerates rapidly. Thousands of new crevasses form in the glacier trunk due to major changes in the forces ("backstresses") acting on the glacier. These changes occur during the Antarctic winter, so they are not related to melt percolation.
20 February 2003: As the glacier acceleration continues and propagates upstream, the lower portion of the glacier loses tens of meters in elevation. The mass of ice delivered to the ocean increases, contributing to a rise in sea level. Larsen B glaciers are too small to significantly affect sea level, but the processes that acted on this area could play out on other, bigger ice shelves.
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