Eemian and Early Weichselian (140–60 ka) Paleoceanography and paleoclimate in the Nordic Seas with comparisons to Holocene conditions

Abstract

Paleoceanographic and paleoclimatic time series were extracted from Norwegian, Iceland, and Greenland Sea (the Nordic seas) sediment sequences covering the time intervals 60–140 ka and 0–15 ka on the basis of stable isotope stratigraphy, planktonic foraminiferal faunas, and sedimentological methods. The proxy temperature records from the Norwegian‐Iceland Sea display a number of high‐frequency and high‐amplitude variations within the last interglacial (the Eemian) indicating marked changes in heat flux at high northern latitudes. Eemian‐Holocene comparisons document that the climate of the Norwegian‐Iceland Sea in the last interglacial was less stable than that of the present interglacial and that the distribution of surface water masses in the Eemian differed from that of the Holocene. Within the Greenland Sea, uniform cold conditions prevailed throughout both interglacials. Cooling of the Nordic seas, as well as the initial growth of the surrounding ice sheets, began within the Eemian interval, before the main increase in global ice volume. Heat flux to the Nordic seas was significantly higher during the interglacials than at any time during the early Weichselian (60–113 ka), and no marked stadial‐interstadial changes in sea surface temperature and deep water ventilation are documented in the early Weichselian records, contrary to the pattern found in North Atlantic sediment records. However, fluctuations in planktonic foraminiferal content, planktonic δ13C, and ice rafting on suborbital timescales, mostly comparable in number and age to the stadial‐interstadial fluctuations in the Greenland ice cores, are demonstrated in our records. The ice‐rafted detritus records provide a more detailed account of ice sheet variability than previously known for the early Weichselian period and demonstrate that glaciers advanced to sea level somewhere around the Nordic seas several times during this interval.