For AWI geologist Juliane Mller the Fram Strait is a key region in the global oceanic circulation. "On the east side of this passage between Greenland and Svalbard warm Atlantic water flows to the north into the Arctic Ocean while on the west side cold Arctic water masses and sea ice push their way out of the Arctic into the North Atlantic. A considerable portion of the Atlantic water cools here on its way to the north and sinks to deeper layers. The circulation of the water caused in this manner drives the global band of oceanic currents like a giant pump and influences, among other things, how much heat the Gulf Stream transports towards Europe," says the scientist.
If the pulse frequency of this circulation pump changes, this gives rise to direct changes in the climate for instance, at the end of the past glacial period and during the transition to our present-day interglacial. "In the past 30,000 years the Gulf Stream has lost an extraordinary amount of force at least twice once 17,600 years ago and about 12,800 years ago. Both times the climate in Europe consequently cooled down significantly and now we also know why," says Juliane Mller.
She and her AWI colleague Ruediger Stein were the first scientists to succeed in reconstructing the sea ice conditions in the Fram Strait for this critical period at the end of the last glacial and thus in finding a direct connection between changes in sea ice cover and fluctuations in the Gulf Stream.
A nine metre long sediment core served as a window into the past for the geologists. It was drilled on a Fram Strait expedition conducted on the research vessel Maria. S. Merian and has such clearly defined layers that the scientists can read it like a book. "This core stems from the western continental slope of Svalbard, a region with an unusually high sedimentation rate. That means a very large number of sediment particles the stores of climate information trickle to the seafloor. This
|Contact: Sina Loeschke|
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research