October 7, 2013
Eiffel Tower-Sized Channels Discovered Beneath Antarctic Ice Shelf
redOrbit Staff & Wire Reports - Your Universe Online
The discovery of hundreds of kilometers worth of channels beneath a floating ice shelf in Antarctica could help experts understand how the ice will respond to changes in environmental conditions, according to a study published Sunday in the journal Nature Geoscience.
Researchers from the University of Exeter, Newcastle University, the University of Bristol, the University of Edinburgh, the British Antarctic Survey and the University of York located the channels using satellite images and airborne radar measurements. The channels are visible both on the surface of the ice shelf and underneath it, because the ice floats at a different height depending on its thickness, the scientists explained.
The channels themselves are 250 meters high, making them nearly as tall as the Eiffel Tower, and the authors said that they are likely to influence the stability of the ice shelf. Furthermore, they also predicted the path of meltwater flowing under the part of the ice that comes in contact with land and discovered that the predicted flow along this ice sheet lined up with the channels at the point the ice begins to float.
“The match-up indicates that the water flow beneath the grounded ice sheet is responsible for the formation of the channels beneath the floating ice shelf,” the University of Exeter explained in a statement. “When the meltwater flowing under the ice sheet enters the ocean beneath the ice shelf, it causes a plume of ocean water to form, which then melts out the vast channels under the ice shelf.”
Experts had believed that water flowed in a thin layer underneath the ice sheet. However, this new study’s findings suggest that it actually flows in a more focused fashion similar to streams or rivers. The speed of the ice flow is heavily influenced by the manner in which water flows beneath the ice sheet, the researchers said, though it is unclear what impact this could have on the future of the ice sheet itself.
“If we are to understand the behavior of the ice sheet, and its contribution to changes in sea level, we need to fully understand the role of water at the base of the ice sheet,” Dr. Anne Le Brocq of the University of Exeter said. “The information gained from these newly discovered channels will enable us to understand more fully how the water system works and, hence, how the ice sheet will behave in the future.”
This is not the first time that channels of approximately this size have been observed. However, the formation of those previous channels had been attributed solely to oceanic processes, not the exiting of meltwater from a grounded ice sheet, Dr. Le Brocq and her colleagues reported. Now that a link to the meltwater system has been established, an analysis of the channels could provide new insight into how meltwater flows at the base of what is essentially an inaccessible ice sheet approximately one kilometer thick.
Image 2 (below): The ice shelf channel is clearly visible on the MODIS Mosaic of Antarctica image map; the predicted flow route of water beneath the grounded ice sheet aligns with the initiation of the ice shelf channel. The dashed line marks the point at which the ice starts to float. Credit: MODIS Mosaic of Antarctica (MOA) Image Map / Anne le Brocq