Last Interglacial and Early Glacial Circulation in the Northern North Atlantic Ocean

Abstract

Studies of marine records from the northwestern European shelf and the northern North Atlantic suggest that last interglacial environments were less stable in this area than in the mid-latitude Atlantic. The influx of Atlantic water masses to the northern North Atlantic was generally higher, and the meridional temperature gradient was steeper, during the last interglaciation than during the Holocene. Strong north-south sea-surface-temperature gradients during the early Weichselian indicate a generally low influx of Atlantic water to the northern North Atlantic, even during interstades. C 2002 University of Washington.

Last Interglacial Climates

“…A prominent cooling noted in the deepsea record from the mid North Atlantic, with an estimated age of about 115,000 to 117,000 yr B.P. (Lototskaya and Ganssen, 1999), may be the same as reported at the MIS 5e/5d boundary by others (Knudsen et al, 2002;McManus et al, 2002). It has been suggested, although it is not universally accepted (Turner, 2000(Turner, , 2002b, that this cold-water event possibly relates to the replacement of woodlands by open vegetation at sites in northwestern Europe.…”

“…Biostratigraphic arguments support the coeval advance of Carpinus across Europe. If the varve counts in Germany are not underestimated, and if the beginning of the Bispingen pollen record is not significantly delayed, then the end of Eemian forests in northwestern Europe would be linked to major circulation shifts in the northernmost North Atlantic (Knudsen et al, 2002). The sea ice advance and ice growth on surrounding lands may also be temporally related (Mangerud et al, 1998).…”

A diatom record of centennial resolution for the Kazantsevo Interglacial stage in Lake Baikal (Siberia)

“…Our age model dates this event at~120 ky BP. A cooling event in the upper part of the Eemian interglacial has also been inferred from some marine sequences of the North Atlantic and Nordic seas (Cortijo et al, 1994;Fronval and Jansen, 1996;Maslin and Tzedakis, 1996;Knudsen et al, 2002) and from a few terrestrial records in Europe (Thouveny et al, 1994;Frogley et al, 1999). It is not clear if these events correspond to the one found in the Lake Baikal sediment record as estimates of their timing and duration are very different between the various studies.…”

Last interglacial atmospheric CO2 changes from stomatal index data and their relation to climate variations

“…4), this climatic event may have been of regional or even global significance. It was speculated by Bjö rck et al (2000) that the dry and cool event c. 2700-3000 years into the Eemian was synchronous with one of two brief last interglacial periods of decreased water temperature and altered circulation in the easternmost North Sea area (Seidenkrantz et al, 1995;Seidenkrantz and Knudsen, 1997;Knudsen et al, 2002). Foraminiferal fauna and isotope data suggest that this period was characterised by a drastically weakened North Atlantic drift allowing southward penetration of arctic waters, which is supported by repeated interglacial cooling episodes recorded also further north in the Nordic seas (Sejrup et al, 1995;Fronval and Jansen, 1996;Fronval et al, 1998).…”