OBJECTIVES
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The questions we want to address in this project are :

• What is the exact sequence of events that control onset, maintenance and end of the PSB around the ice edge, under the ice-pack and in adjacent open waters?
• How do physical and chemical properties vary in space and time, and what are the processes responsible for those variations?
• What are the key phytoplankton groups and species involved, and what do control their succession?
• How much of the organic carbon produced by the PSB is transferred through the food web and toward the bottom sediments, and following which pathways?
• What is the exact role of the Arctic Ocean PSB in the ecosystem functioning, over an annual cycle?
• Will pan-Arctic marine primary production increase or decrease during the coming decades?
• What will be the impacts of a different primary production for Northern communities and for the role of the Arctic Ocean within the global ocean productivity system?

To answer these questions, we will consider current trends and, thanks to the knowledge gained from process studies, we will try to predict the fate of primary production and marine ecosystems in the Arctic Ocean. Predictive ocean coupled physical-biogeochemical models are powerful tools for understanding current trends and testing future scenarios. They also provide a conceptual frame for synthesizing diverse process studies. Their limitations for predicting actual trends at desired time and space scales are, however, well known (see e.g. Popova 2012 for the Arctic Ocean). Therefore, in this project, we will look at current trends based on remote sensing data, try to reproduce current trends with our coupled physical-biogeochemical models (nowcast), and make predictions of future trends for different scenarios of climate change. But we will also use a paleoceanographic approach to try to determine how the Arctic marine ecosystem responded to past climate variations and, thereby, validate to some extent our predictions. Similarly, traditional Inuit knowledge linking sea ice, climate change and the availability of marine resources (fish, marine mammals, seabirds) will also be used to infer on trends in ocean productivity. Just as the traditional knowledge will inform and complement the science, results obtained from the Green Edge project will  provide local experts and Indigenous knowledge systems with a better understanding of the current Arctic environmental change. A two-way exchange between marine scientists and local Indigenous Experts appears to be a powerful approach to get a full appraisal of modifications in the biophysical regime of Arctic waters. While any of those four approaches (past, present, future, and human) taken alone involves significant limitations, the four put together form an incredibly powerful approach.

The project will target the following specific objectives:

• Understand the key physical, chemical and biological processes that govern the PSB in the Arctic Ocean.
• Identify key phytoplankton species involved and model their growth under various environmental conditions.
• Predict the fate of the PSB and related carbon transfer through the food chain (from plankton to humans) and toward the bottom sediments over the next few decades.
• Determine how the PSB responded to past climate variations.