Chelsea Harve reports that a new mapping project has given scientists one of their most complete looks yet at the movement of glaciers all around Antarctica. The key finding: Far more glaciers are losing ice than gaining ice. The study further fuels a growing concern among scientists about the factors affecting the Antarctic ice sheet—namely, that warm ocean waters are helping to melt glaciers and drive greater levels of ice loss, particularly in West Antarctica.
“The strong impact of ocean onto Antarctic ice sheet dynamics, or the knowledge that we have about it, is reinforced by our study,” said lead study author Hannes Konrad of the University of Leeds in an interview with E&E News. The research, published Monday in the journal Nature Geoscience, focuses on Antarctica’s marine-terminating glaciers, or glaciers that back directly up to the ocean. These glaciers are typically all structured in a similar way.
The ice rests on top of the ground and remains connected to the bedrock up to a point known as the grounding line. At the grounding line, the ice detaches from the bedrock and juts out into the water as a kind of floating ledge, or ice shelf, which helps to stabilize the glacier and hold back the flow of ice behind it. Meanwhile, ocean water seeps beneath the ice shelf and washes up against the base of the glacier.
The position of the grounding line can tell scientists a lot about the stability of any given glacier and its potential to contribute to sea-level rise. If the ice at the bottom of a glacier melts, the point where it connects to the bedrock moves backward, farther inland, losing ice to the ocean in the process. As this happens, the floating ice shelf in front of it also lengthens and thins, increasing its chances of breaking and allowing even more ice to flow out from behind it.
Because of their immense potential to influence global sea levels—the entire Antarctic ice sheet contains enough ice to raise the ocean by about 200 feet—scientists have focused increasing attention on ice loss from Antarctic glaciers and the climate factors that may influence that process in the coming years. Many studies have focused on mapping ice loss from specific glaciers.
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