Ocean ‘once covered in ice half a mile thick’

THE ARCTIC Ocean may have been covered by an ice shelf more than half a mile deep and nearly twice the size of the ice sheet that covers Greenland, Yorkshire academics claim today.

In a paper to be published this morning, researchers will say that a huge floating platform of ice formed from the flow of glaciers into the ocean is a “missing component” of the Earth’s climate system.

The study, led by Sheffield University, is the first of its kind and builds on earlier work carried out in Stockholm which suggested the existence of kilometre-thick shelves of ice.

Dr Ed Gasson, who led the new research, said mathematical analysis had now shown that the ice could only have reached such a depth if it had covered the entire Arctic Basin.

“The study is important because it opens up further research into what role this previously missing piece played in Earth’s glacial periods,” Dr Gasson said.

“Although these periods of Earth’s history have been extensively studied there are many things that are not fully explained. What impact an Arctic ice shelf had on the climate system is a big unanswered question.”

The notion of Arctic ice shelves was first mooted in the 1970s, but with only limited evidence to support it. Scientists now believe that the ice shelf formed during the penultimate glacial period about 140,000 years ago.

Floating ice shelves can leave no traces unless they grind away the sea floor, leaving open the possibility that a thinner ice shelf also formed during the last glacial period.