The West Antarctic Ice Sheet lies mainly in the South Pacific ocean and contains over 3 million cubic kilometers of ice covering about ten percent of the total Antarctic area. It is Earth's only ice sheet that could possibly collapse and slide into the ocean, said Bindschadler, because it sits atop slippery marine sediments below sea level. Charles R. Bentley, a University of Wisconsin glaciologist and one of the researchers speaking at the conference, said it is important to keep in mind how long such a collapse may take. If the collapse takes place over 5,000 years, the change in sea level would only be about 1 millimeter per year, about half as fast as the current rise. To understand the behavior of the West Antarctic Ice Sheet, scientists must understand how the ice moves.
Ice streams are different than glaciers in that they are bordered by ice instead of rock.
Measuring the flow of these vast ice streams from the ground can be treacherous, so many researchers rely on satellite observations. Bindschadler compared satellite images of ice streams taken over the last 35 years, which included recently declassified U. S. intelligence data. He found that ice streams once thought to flow at a constant rate are actually slowing down, making the question of whether the West Antarctic Ice Sheet as a whole is wasting away much more complicated. Ted A. Scambos, a University of Colorado glaciologist, and Mark A. Fahnestock of the University of Maryland found the same slow-down in more recent satellite images. It's becoming clear that's not the case.