Huge 250 metre high ice channels have been found beneath the Antarctic which could be speeding up melting of the ice shelf.
The channels are almost as tall as the Eiffel Tower and are thought to stretch hundreds of kilometres along the ice shelf.
Scientists believe they have implications for ice-shelf stability around them but added that the long-term implications for the ice sheet are still unknown. The British researchers used satellite images and airborne radar measurements to reveal the channels under the Filchner-Ronne Ice Shelf in West Antarctica. The channels can be seen on the surface of the ice shelf, as well as underneath, because the ice floats at a different height depending on its thickness. ‘The biggest challenge was the lack of field data that is available to investigate the nature of the channels, we can observe them from above in the satellite imagery, but have little direct observations from radar,’ Dr Anne Le Brocq from the University of Exeter, told MailOnline.
Using what data they had, the researchers were able to predict the path of meltwater flowing under parts of the ice which were in contact with the land. They discovered that these channels lined up with areas where similar flows of water are thought to exist under the ice shelf at the point where the ice starts to float.
According to the researchers, 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. ‘It was a bit of a “Eureka moment” when I found the predicted water flow routes lined up with the channels,’ said Dr Le Brocq. ‘They provide us with a very useful way of investigating an otherwise fairly inaccessible environment.’
When the meltwater flowing under the ice sheet enters the ocean beneath, it causes a plume of ocean water to form, which then melts out the vast channels under the ice shelf. Previously, it was thought that water flowed in a thin layer beneath the ice sheet, but the evidence from this study suggests it flows in a more focused manner, much like rivers. The way in which water flows beneath the ice sheet strongly influences the speed of ice flow. Vast channels such as this have been observed elsewhere, but their formation has been credited to purely oceanic processes rather than meltwater flowing out of the grounded ice sheet.
