Big Pic: 820-Foot-High Tunnels Discovered Under Antarctic Ice

The hidden channels are nearly as tall as the Eiffel Tower.

British Antarctic Survey Camp and Survey Plane
Neil Ross

This is the camp from which scientists discovered 820-foot-high channels underneath an ice shelf—a piece of ice jutting out into the ocean from land—in Antarctica. The tunnels are nearly as high as the Eiffel tower.

Researchers from several universities in the U.K. and the British Antarctic Survey flew a plane over the Flichner-Ronne Ice Shelf in West Antarctica. (You can see the plane, a Twin Otter, parked at camp above.) Radar from the plane, as well as satellite photos, revealed that surface features on the ice corresponded to tunnels at the bottom of the ice.

The placement of the channels suggests they were formed from meltwater flowing underneath the ice, over land, and into the ocean. That also suggests water underneath ice sheets pours out into the ocean in focused channels, sort of like under-ice rivers. Scientists previously thought overland meltwater flowed underneath ice sheets in thin, continuous layers.

The British team will now use its newfound knowledge of the under-ice tunnels to predict how exactly that ice shelf will melt in response to climate change. The researchers published a paper about their work in the journal Nature Geoscience.

An Under-Ice Channel
This illustration shows the survey plane getting measurements of the height of a channel underneath the Flichner-Ronne Ice Shelf. It also shows the channel's size compared to the Eiffel Tower and to the Tower Bridge in London.Anne Le Brocq