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Publication and Communication

Sub-centennial Holocene fluctuations of Atlantic water inflow and sea ice distribution in the western Barents Sea, European Arctic.

Authors

S. Berben, K. Husum, P. Cabedo Sanz, S. Belt

 

First Authors affiliation

UT

Event

4th Open Science Meeting

Goa; India

11-16 February 2013

 

POSTER

 

Abstract

The North Atlantic Current (NAC) brings warm and saline water into the Arctic: this inflow is balanced by the outflow of cold surface water and by the formation of deep water to the south, which is part of the Atlantic Meridional Overturning Circulation (AMOC). Changes of the AMOC can greatly affect the global ocean circulation and climate, especially at high latitudes where the inflow of warm water, heat exchange and its effect on sea ice formation is essential for environment and society. Hence, it is crucial to establish the natural range of oceanographic fluctuations within this area. Here we investigate a continuous high resolution record from the Kveithola Through, western Barents Sea, in order to elucidate the past variability of the Atlantic Water flow and sea ice distribution throughout the Holocene.

The age model is based on nine AMS C14 dates, and shows sediment accumulation rates up to 0.034 mm/yr, enabling a sub-centennial resolution. Planktic foraminifera and stable isotopes were analysed. In addition, the sea ice biomarker IP25 is measured in order to establish a reconstruction of temporal changes in sea ice cover. Finally, Mg/Ca ratios will be presented in order to further quantify the surface water mass properties as SST and SSS.

The planktic foraminiferal stable isotopes show warming at ca. 10 000 cal yr BP followed by a cooling from ca. 8 000 cal yr BP until present day conditions. This long-term cooling correlates to the decreasing June insolation at 70° N following the orbital forcing. The planktic foraminiferal fauna has two dominating species: the polar N. pachyderma (sin) and the sub-polar T. quinqueloba. The early Holocene is dominated by N. pachyderma (sin), while throughout the mid and late Holocene T. quinqueloba dominates the fauna with values up to 75% possibly reflecting a high nutrient availability close the sea ice margin. The sea ice indicator IP25 shows that the core site is influenced by sea ice in the early Holocene. From ca. 8 500 to 2 500 cal yr BP the sea ice gradually decreases. After this time the IP25 record increases suggest a returned appearance of sea ice although in a smaller extent than during the early Holocene.

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