Merging the Arctic paleoceanography into the Earth's global climate/ocean history

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***The Arctic Ocean is an important component of the climate system because of its sea-ice cover modulating energy budget through albedo, and of its exchanges with the northern Pacific and North Atlantic that play a role on the global ocean circulation. However, its history is still unresolved, notably due to i) the lack of a robust chronology from sedimentary archives, ii) difficulties in recovering such archives in the Arctic, and iii) equivocal proxy records of environmental changes. Hence merging the Arctic Ocean into the global Earth and ocean climate system remains a challenge. This is the issue I will focus on in the forthcoming years. Sediment cores recently raised from the Arctic Ocean and the subarctic seas of the North Atlantic will be used for the documenting of the status and interactions of the Arctic Ocean during recent glacial/interglacial cycles. Drill cores from the International Ocean Discovery Program (IODP) will be used for the dating of the inception of marine conditions and the subsequent evolution of the Arctic basin towards the late Cenozoic perennial sea ice cover. A strongly coordinated Canadian participation to international efforts and tight collaborations with foreign scientists, notably from Germany through the International NSERC-CREATE program on "processes and impacts of climate change in the North Atlantic Ocean and the Canadian Arctic" (ArcTrain), provide the frame of the present proposal. The research planned here aims at contributing to partner studies of cores from Arctic Ocean ridges and subarctic Seas with geochemical and radiochronological investigations. The three main objectives are : i) to better constrain the age of the marine invasion of the Arctic Ocean and its Cenozoic evolution based on Rhenium-Osmium isotope studies and; ii) to set a consensual Late Quaternary chronostratigraphy of Arctic ridge records, based on the decay of Uranium series isotopes in sediments from recently recovered cores; iii) to further develop geochemical and isotopic tracers of past and present fluxes within the Arctic Ocean and towards adjacent subarctic seas during warm episodes of the past and the present warming trend. This work aims at providing critical information for climate and geochemical modelling efforts undertaken within the framework of international research initiatives supported by other funding agencies. A cohort of graduate students with state-of-the-art training in environmental isotope geochemistry and/or geochemical and climate modelling will be directly involved in the program.