About 60.000 to 70.000 years ago, in a particularly cold part of the last glacial period, large parts of Northern Europe and North America were covered by ice sheets. The European ice sheet spanned a distance of more than 5000 kilometres, from Ireland and Scotland via Scandinavia to the Eastern rim of the Kara Sea (Arctic Ocean). In North America, large parts of what is now known as Canada were buried under two large ice sheets. Greenland and parts of the Bering Sea coastline were glaciated too. What was the ice situation like even further North, in the Arctic Ocean? Was it covered by thick sea-ice, or maybe with the tongues of these vast ice sheets were floating on it, far beyond the North Pole?
Scientific answers to these questions were more or less hypothetical so far. In contrast to deposits on land, where erratic boulders, moraines and glacial valleys are the obvious landmarks of glaciers, only few traces of vast ice shelves had been found so far in the Arctic Ocean. Geoscientists from the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI) and MARUM Center for Marine Environmental Sciences at the University of Bremen have now compiled existing evidence from the Arctic Ocean and the Nordic Seas, and combined it with new data to arrive at a surprising conclusion.
According to their study, the floating parts of the northern ice sheets covered large parts of the Arctic Ocean in the past 150,000 years. Once about 70,000-60,000 years ago and also about 150,000-130,000 years ago. In both periods, freshwater accumulated under the ice, creating a completely fresh Arctic Ocean for thousands of years.