A new study in Geophysical Research Letters shows that the retreat of Antarctica’s fast-flowing Thwaites Glacier is expected to speed up within 20 years, once the glacier detaches from an underwater ridge that is currently holding it back. Thwaites Glacier, which drains into west Antarctica’s Amundsen Sea, is being closely watched for its potential to raise global sea levels as the planet warms. Neighboring glaciers in the Amundsen region are also thinning rapidly, including Pine Island Glacier and the much larger Getz Ice Shelf.
The new study allows scientists to understand what is happening at the glacier’s grounding line—where the glacier leaves land and floats into the sea, exposing the ice to warm ocean currents. The goal of NASA’s Ice Bridge campaign is to map the topography of vulnerable regions like this in Antarctica and Greenland by flying over the ice sheets with ice-penetrating radar and other instruments.
The discovery that Thwaites is losing its grip on a previously unknown ridge has helped scientists understand why the glacier seems to be moving faster than it used to. In the past, when Thwaites was thicker, the glacier must have been anchored more solidly on that ridge but now that is changing. The new data allows scientists to predict when the last bit of floating ice will lift off the ridge. When this happens more ice is expected to come streaming out of the Thwaites Glacier.