As a contribution to SBI phase III efforts, it is critical to improve both our understanding of the Arctic Ocean carbon cycle and predictive capabilities for future responses to environ-mental changes. This requires data integration, synthesis, and modeling activities that lead to new system-level understanding of present and future carbon cycling in the Arctic Ocean. A central hypothesis to be tested in this research is that:
H. The physical forcing (e.g., sea-ice, nutrient supply) and biological responses exert fundamentally different controls on the carbon cycle and the rates air-sea CO2 exchange, NCP and export production in the Chukchi Sea compared to other shelves.
This project will compile organic and inorganic carbon data, and rate measurements (e.g., 234Th/238U export) collected during SBI phase II with other hydrographic, biogeochemical and carbon datasets from across the Arctic. Incorporation of these datasets provides a pan-Arctic context for understanding carbon dynamics in the present and under climate change scenarios (e.g., changes in sea-ice melt, river input, stratification, and biological responses). Specific objectives that will test the central hypothesis, include:
Objective 1: Determine stocks of inorganic and organic carbon in the Chukchi Sea and pan-Arctic (including anthropogenic CO2);
Objective 2: Determine rates, including air-sea CO2 gas exchange, net community production, and export production on the Chukchi and other shelves, and in the adjacent Arctic Ocean basin;
Objective 3: Synthesize rates and stocks using carbon mass balance approaches. This effort includes comparative analyses of the Chukchi shelf with other shelves (carbon cycling on inflow versus interior shelves) and anticipated changes in the Arctic carbon cycle. These analyses will advance understanding through collaborative synthesis and modeling efforts, and, national and international coordination through workshop meetings in 2008 and 2010.
