OCEANIC EVIDENCE FOR COHERENT FLUCTUATIONS IN FENNOSCANDIAN AND LAURENTIDE ICE SHEETS ON MILLENNIUM TIMESCALES

PROXY temperature records from Greenland ice cores(1,2) and North Atla ntic sediment cores(3) have provided evidence for a high degree of cli mate instability during the last glacial period. Much of this variabil ity seems to be linked with the dynamics of the Laurentide ice sheet t hat covered North America at this time(3), which discharged iceberg fl otillas into the North Atlantic that are now recorded in sediment core s as Heinrich events(4). How (if at all) this variability was manifest ed on the other side of the Atlantic-in the Nordic seas and the ice sh eets of northwest Europe and Scandinavia-has been unclear. Here we pre sent sediment, microfossil and oxygen isotope data from a sediment cor e in the Norwegian sea, which reveal cooling events and iceberg discha rges analogous to Heinrich events. We show that these climate fluctuat ions in the Norwegian Sea were in phase, or were phase-locked, with ai r temperatures over Greenland, suggesting that the rapid changes in he at fluxes in the North Atlantic recorded in previous records(3) were f elt in this high-latitude region. The iceberg discharges in our record seem to have come from the Fennoscandian ice sheet, implying that thi s and the Laurentide ice sheets fluctuated coherently on timescales sh orter than those of Milankovitch orbital cycles.