The time that has passed since the rocks' exposure indicates that the ice did not begin its retreat until 10,000 years ago-at least 3,000 years after the oceans began to rise. What's more, the ice sheet shows no signs of halting its inland march, Hall says. At its current pace, it will disappear in 7,000 years regardless of global warming. But that prediction is extrapolated from only four past positions of the ice sheet. Antarctica may be shrinking, but oddly enough, it is not melting, at least not directly.
Snow falls in the interior, and the streams carry ice to the sea, where it breaks into icebergs.
Until now, no one knew what was happening at the streams' source, but researchers are a giant leap closer to understanding just how these ice streams work, thanks to new images made by a Canadian satellite called Radarsat. That's what our image does. In times past, a single velocity measurement required that someone go to the spot and plant a stake with a Global Positioning System receiver in the ice, leave for a certain amount of time, then go back and see how far it had moved. In the barren chill of the Antarctic, that's no easy task. In the past we were really unclear about what the ice sheet looked like and how it changes.