Abrupt climatic change during the last interglacial–glacial cycle in the polar North Atlantic

Abstract

We have investigated five sediment cores from the margin and abyssal plain off western Svalbard-Barents Sea in the polar North Atlantic. We discuss the palaeoceanography and its relationship to glacial history during the last interglacial–glacial cycle based on detailed stratigraphic analyses of planktic and benthic foraminiferal fauna, oxygen and carbon isotopes on foraminifera, ice-rafted debris (grains >500 μm) and radiocarbon dates. The sediment cores, combined, cover the last interglacial–glacial cycle, including marine isotope stage (MIS) 5–1. Sedimentation rates are generally high ranging from 3 to >100 cm/1000 years. Atlantic Water repeatedly reached the polar North Atlantic during the last interglacial–glacial cycle and was present for at least 50% of the total time interval. Periods having Atlantic Water advection, termed HP-zones (HP=high productivity), are characterised by high planktic foraminiferal production, a small increase of benthic and subpolar planktic foraminifera. Benthic foraminiferal and stable isotope data indicate active deep-water formation during the HP-zones. In substage 5e there are indications of sea-surface temperatures similar to those of today. The major glaciations on Svalbard during the last interglacial–glacial cycle are related to HP-zones. Some HP-zones correspond to an early build-up phase of the ice sheets. Peak glacials all correspond to one HP-zone that subsequently is terminated by a meltwater event. However, periods with advection of Atlantic Water during mid-MIS 3 do not correlate to a glacial phase on Svalbard, but rather to the western Fennoscandian Ice Sheet. The records in the present study are correlated to the northeast Atlantic, the Arctic Ocean and to the Greenland Ice core record and show parallel millennial scale variability.