Digging into our icy past to forecast future

A New Zealand-led team of 24 international scientists has set up a drilling site on the Ross Ice Shelf, about 350km away from Scott Base.

That expedition — led by Professor Christina Hulbe and Dr Christian Ohneiser of Otago University — is drawing on a Kiwibuilt drill using hot water to bore through hundreds of metres of glacial ice to access the ocean and sea floor beneath their remote camp.

The Ross Ice Shelf is Earth’s largest expanse of floating glacial ice, and is fed by glaciers flowing from the West Antarctic Ice Sheet and through the Transantarctic Mountains and by new snow falling on its surface.

The ice is continually moving, flowing away from the land and toward the open ocean, and eventually breaking off as icebergs.

At the drill site, which the scientists visited two years ago, the ice is moving as fast as two metres each day.

Oceanographers and geophysicists are installing instruments for long-term monitoring of conditions in the ocean cavity and the ice shelf, while geologists are lowering a core barrel down the hole to sample sediments on the sea floor.

A remotely operated submarine on a 3km-long tether is also being used to dive down the borehole to observe ocean, sea floor, and ice conditions in the area all around the drill site.

At the surface, an atmospheric physicist will install a regional network of smart weather stations and geophysicists and surveyors will use ice-penetrating radars and acoustic techniques to image

At the moment the Ross Ice Shelf appears to be stable, but we don’t know for sure. Dr Christian Ohneiser

internal structures of the ice shelf.

“We know that in the past, climate warming caused ice shelf and ice sheet retreat in the Ross Sea,” Hulbe said.

“Now we need to find out more about the actual physical processes and the rates at which they act.

“That knowledge is one of the keys to making better projections of future change.”

Ohneiser noted the Ross Ice Shelf was a “major interface” between the West Antarctic Ice Sheet and the Southern Ocean.

“At the moment the Ross Ice Shelf appears to be stable, but we don’t know for sure. But we do know that it has changed quickly in the past.

“We need data from the places that are still covered by ice — not just at the easy to get to places around the edge.”