Atlantic Water Advection to the Northern North Atlantic: AN Historical View from Marine Sediments in the Western Barents Sea and Fram Strait

Atlantic Water in the West-Spitsbergen Current (WSC) is the major carrier of oceanic heat to the Arctic Ocean. A recent study based on planktic foraminifera from Fram Strait (e.g. Spielhagen et al, 2011; Science vol. 331) suggests enhanced oceanic heat transfer to the Arctic Ocean in the early 21st century linked to the polar amplification of global warming. Still, the intricate interaction between circulation changes, salinity of the mixed layer and sea-ice dynamics, as well as contradictory information provided by a variety of paleoceanographical proxies, hamper our understanding of the timing, spatial significance and impact of recent oceanographical changes in the northern North Atlantic. The main core of Atlantic water entering the Nordic Seas flows along the western coast of Norway (Norwegian Atlantic Current - NAC) and the western Barents Sea (WSC), before penetrating into the Arctic Ocean. Our ongoing study is based on a collection of multi-cores recovered from areas presently affected by the NAC and WSC : the western and south-western Barents Sea, and Fram Strait. They offer the opportunity to investigate, at decadal to sub-decadal scales, changes in the nature and intensity of the poleward AW flow within the last ca. 500 years. Calcareous (coccoliths) and organic-walled (dinocysts) skeletal remains of phytoplankton are investigated in order to provide both qualitative and quantitative (modern analogue technique) reconstructions of the physico-chemical status of the surface mixed layer. These proxy-records, together with alternative indicators such as ice-rafted detritus and planktic foraminiferal assemblages, are critically discussed in view of historical hydrological datasets in the area which extend back to ca. 150 years, and a few available marine and terrestrial records from the northern North Atlantic and surrounding continents.