Isotopic tracers and chronometers of Earth surface processes (climate & ocean dynamics)

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The research follows two complementary tracks contributing to international initiatives about Earth system science issues: i) the dynamics of climate and ocean, and ii) the impact of climatic changes on land erosion, geochemical cycles and sea-levels, with some focus on high Northern Hemisphere latitudes. The first track aims at predicting the future of the Canadian Arctic under a warmer globe with attention paid to i) the fate of sea-ice and its impact on sedimentary regimes, ii) continental ice decay and runoff, iii) their impact on the Atlantic Meridional Overturning Circulation and on global sea-levels. Conditions during past "warm" intervals, the Pliocene and thermal optima of the past- and present interglacial stages, and transition intervals towards such climatic optima, will be reconstructed and used to identify changes in boundary conditions and for testing current climate model abilities to reproduce such past-synopses. Stable, radioactive and radiogenic isotope analysis of geological archives, in particular of deep-sea sediments, constitute primary tools for the planned studies. They provide access to geological time and a large array of paleo-environmental parameters, thus to "pre antropogenically-modified" states of the Earth system, at time scale varying from million years to the present. Complementary efforts towards using some of the above isotopic tracers for the monitoring of modern environments constitute the second research track, through a planned project of the International Atomic Energy Agency on "Isotopic tools to assess anthropogenic impacts on water quantity and quality on large river systems" . Here, the focus will be on the Mackenzie, St. Lawrence, circum-Hudson Bay and Hudson Strait rivers, both for tracer-calibration purposes and the documenting of on-going anthropogenically- vs naturally-driven processes with impact on soil erosion, runoff, sediment and chemical fluxes from the land to the ocean. This program has thus basics and socially relevant objectives and will permit the training of nearly 20 graduate or post-doctoral scientists in domains of importance for the development of the North and/or the assessment of soil and water resources under the present anthropogenic pressure.