Channels nearly as tall as the Eiffel Tower gouge into the undersides of floating ice in western Antarctica. The recently discovered channels could influence how quickly Antarctic ice sheets slip into the sea, melt, and contribute to rising sea levels.
Torrents of water from melting ice sheets may carve the approximately 250-meter (820-foot) tall and equally wide channels. The channels start where geographers calculated that melt water would run off the solid ground of Antarctica and under the floating Filchner–Ronne Ice Shelf. This suggests that melt water moves along a distinct course like a river beneath the kilometer-thick ice sheet, as opposed to a thin layer beneath the entire sheet.
Understanding how these channels form could alter the way scientists model melting ice and help them understand events such as when a massive chunk of the Filchner–Ronne Ice Shelf broke away and shattered in less than 24 hours during January of 2010. That chunk was larger than the state of Rhode Island.
“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,” said lead author Anne Le Brocq of the University of Exeter in a press release. “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.”
Once that hidden river of melt water reaches the sea, it forms a plume and warms the surrounding salt water. The warmed waters then wears a channel into the floating ice of the Filchner–Ronne Ice Shelf of western Antarctica.
The process seems like the inverse of how a canyon forms on dry land. Except instead of water burrowing a channel down into the Earth, the warm water carves a channel up into the ice shelf.
However, since all of this occurs beneath hundreds of meters of ice in one of the most inhospitable environments on Earth, scientists must use satellite images and radar measurements from airplanes to estimate the how the hidden ice behaves as it melts away.
Scientists had observed the channels before, since they leave a distinctive line on the surface of the ice sheet. However, Le Brocq and her team have interpreted the channels as signs of hidden rivers of melt water.
Nature Geoscience published this new explanation of the melt water channels.
TOP IMAGE: A massive piece of the Filchner–Ronne Ice Shelf breaking off in January of 2010 (NASA, Wikimedia Commons)