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Kvartære geosystemer

Ocean circulation changes off southern Greenland during the abrupt climate events of mid-to-late MIS 3

PhD candidate: Lisa Griem

Supervision: Prof. Eystein Jansen, Dr. Trond M. Dokken and Sarah M. P. Berben

Project period: August 2016 – July 2019

This PhD project is part of the ice2ice project which is funded by the European Research Council.

 

The aim of this PhD project is to develop high-resolution climate records throughout the last Glacial based on sediment cores retrieved during the ice2ice cruise GS16-204 to the Eirik Drift. The Eirik Drift is a key location to study changes in Arctic freshwater export, the extent of the Greenland ice sheet as well as deep-water formation and therefore strength of the thermohaline circulation. The main focus hereby lies on the changes between Stadial and Interstadial climate conditions.

The investigated time period of Marine Isotope Stage 3 includes several of those Stadial-Interstadial transitions, known as Dansgaard-Oeschger events. Here Greenlandic temperature records show an increase of up to 15°C in less than a decade. The reasons for those rapid climate changes are not yet fully understood but Nordic Sea´s sea ice, freshwater surges and the height of the Greenland ice sheet seem to play a major role.

The first step in order to shed light on triggers and consequences of DO-events is to establish an independent age model for the sediment records by using conventional AMS 14C dating and tephrochronology. Then a multi-proxy approach will be applied in order to receive an in-depth view on underlying mechanisms of abrupt climate changes. Stable isotopes will be measured on both planktic and benthic foraminifers to constrain changes in surface- and deep-water mass properties. Ice rafted debris and foraminifers will be counted to evaluate the interaction between ice sheet extent, freshwater input to the North Atlantic via the Subpolar Gyre and ocean circulation changes.