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CanClim: Late Holocene multi-decadal to centennial scale oceanic variability on the eastern Canadian shelf linked to North Atlantic climatic changes

A series of distinct millennial to centennial scale oceanic and climatic oscillations occurred in the North Atlantic region during the last 3000 years. There is increasing evidence that variable freshwater advection from the Arctic Ocean via the East Greenland Current route and local meltwater supply from the Greenland Ice sheet is linked to these oscillations and caused a widespread decoupling of surface and subsurface water conditions. Particularly within the subpolar North Atlantic this decoupling is documented along the N/NW boundary currents of the Subpolar Gyre, i.e. the East Greenland Current, and West Greenland Current. However, little is known concerning the late Holocene freshwater advection via the second major Arctic Ocean freshwater outflow route, the western Canadian Arctic Archipelago, which strongly influences the Labrador Current properties. The Labrador Current, in turn, together with the East and West Greenland Current affects the Subpolar Gyre circulation, which regulates the heat advection into the northern North Atlantic and thus, northern hemisphere climatic conditions. As only limited information on freshwater outflow changes via the Canadian Arctic Archipelago/Labrador Current route is available, our understanding of millennial to centennial scale North Atlantic climate variability is constrained.

            The proposed multi-proxy study combining qualitative (foraminifer assemblages) and quantitative (stable isotope and trace element studies, alkenones) reconstructs for the first time, from marine sediment cores, surface (freshwater) and subsurface water conditions on the eastern Canadian shelf at a high resolution. Radiocarbon dates and radionuclide measurements, obtained during a pilot study, prove that these cores, collected in 2015 during the MSM45 and 46 cruises, resolve late Holocene oceanic and climatic changes at a multi-decadal to centennial scale. The proposed multi-proxy investigations of surface and subsurface water properties, spanning the eastern Canadian shelf from Hudson Strait to the Gulf of St. Lawrence, will allow assessing the link between oceanic changes, and the subpolar North Atlantic multi-decadal to centennial scale climate variability during the late Holocene.