As much of the scientific community will attest, Antarctica is slowly losing ice to the sea. It looks like this loss of ice is accelerating in the Western Antarctic ice shelf. In a new study, spearheaded by University of Texas at Austin’s Institute for Geophysics (UTIG), forty years of satellite imagery has been examined which reveals that the western Antarctic ice shelf, primarily made up of the Pine Island and Thwaites glaciers, is breaking off from Antarctica.
Dr. Joseph MacGregor explains, “Typically, the leading edge of an ice shelf moves forward steadily over time, retreating episodically when an iceberg calves off, but that is not what happened along the shear margins”. UTIG’s progressive satellite imagery reveals that the margins where these slowly breaking glaciers tend to hang on to rocky walls or other bigger glaciers, are slowly moving inland. As the glacier’s grip on to the Antarctic continent moves inland, it loosens. As this trend continues, eventually these glaciers will break off, completely.
This imagery from the UTIG shows that as the margins, at which the glaciers grip on to land, start to weaken, rifts are created between the new ice shelf and the land, further accelerating the breakage.
From UTIG: In this series of Landsat images of the outer edge of Pine Island Glacier from 1972 to 2011, you can see how the coastline (red line) advances seaward (to the left), then shifts back inland as large masses of ice calve off, and then starts the cycle over again. Meanwhile, the northern shear margin (above center), where the glacier clings to neighboring ice or rock, fractures and retreats. Produced by Joseph MacGregor and Ginny Catania,
This may be part of the reason why the last ten years of data show the most rapid breakage, for the Western Antarctic ice shelf.
Determining exactly how long these the glaciers will take to break off will definitely require further observation. It will also be interesting to see what – if any other – glaciers are on their way to breaking away.