Contrasting interglacials in the Arctic Ocean – an Eemian-Late Holocene comparison based on stable oxygen and carbon isotopes

• Main Authors: Spielhagen, Robert F., Bauch, Henning A.
• Format: Conference Object
• Language: unknown
• Published: 2011
• Subjects: Arctic; Arctic Ocean; Fram Strait; Nordic Seas
• Online Access: https://oceanrep.geomar.de/id/eprint/13077/

The last interglacial (Eemian), the first interval in marine isotope stage 5 (MIS 5) is often considered as a possible analog for future climate conditions forced by anthropogenic greenhouse gas emissions. The reason lies in decades of research on the Eemian which have shown that in many areas in the northern hemispheric mid-latitudes hypsithermal Eemian climate conditions were warmer than at any time in the Holocene. In the Atlantic sector, northward Atlantic Water transport is the major means of heat transfer to the northern high latitudes. As a possible explanation for Eemian-Holocene differences, one may thus propose a stronger and warmer Atlantic Water advection to the Arctic for the peak Eemian than for the Late Holocene. Since surface-near water mass properties are reflected in the oxygen and carbon isotope composition of planktic foraminifers, a comparison of such values from Eemian and Holocene sediments can give hints on possible differences in Arctic Ocean environments in these intervals. While there is a dense coverage of isotope values from planktic foraminifers in sediment surface samples available for large parts of the Arctic Ocean and the northern Nordic Seas, the number of suitable Eemian isotopic records is still rather limited. The situation is complicated by meltwater influences on surface- near waters in the MIS 6/5 transition and by the generally rather low sedimentation rates in the Arctic which often restrict Eemian deposits to a few centimeters. Comparison of available records, mostly from the Fram Strait and Eastern Arctic Ocean, show ca. 0.5‰ higher oxygen isotope values in the Eemian than in the Late Holocene. Carbon isotope differences are variable but the number of sites with slightly lower values in the Eemian is dominating. The results may be interpreted in several and partly contrasting ways, involving differences in river run-off, salinity, temperature, ice-coverage, and main habitats of the planktic foraminifers.