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Science-Pacific
Region-Ocean Sciences-People-Lisa Miller home page
Lisa MillerCarbon Cycling in Arctic Waters and Response to Climate Change
The Canadian Arctic Shelf Exchange Study (CASES) The Canadian Arctic Shelf Exchange Study is an ambitious program attempting to comprehensively study how climatology and ice cover control carbon cycling on the Mackenzie Shelf over the course of an entire year that at last count included nearly 130 PIs. Personally, my work within CASES is focussing on direct measurements of carbon fluxes on the Mackenzie Shelf and at its boundaries with the atmosphere, the sediments, and the deep Arctic basin. Since this is way too much work for one person or group, I am directly collaborating with Al Mucci of McGill University (to study the importance of inorganic detritus in carbon export), Tim Papakyriakou at the University Manitoba (to determine CO2 flux rates through sea ice), Jody Deming of the University of Washington (to understand the importance of ice biota in those CO2 fluxes in the ice), Ingunn Skjelvan and Richard Bellerby of the University of Bergen (to follow the evolution of surface water pCO2 throughout the experiment), Peter Galbraith of the Maurice Lamontagne Institute (to understand the importance of turbulent diffusion in carbon transport), and Christine Michel at the Freshwater Institute and Michel Gosselin of the University of Quebec at Rimouski (generating water-column total carbon budgets). I am also responsible for many of the water column carbon measurements that will be used by others in the project.The International North Water Polynya Study (NOW) The inorganic carbon team on the NOW project included Tish Yager and Doug Wallace's (formerly of Brookhaven National Laboratory) group, as well as myself, and based on a comprehensive data set covering the period from April to October, we found that there was a net biogenic and/or advective loss of carbon from the surface waters through the season, and that those surface waters are undersaturated in CO2 during the entire ice-free period (pdf). These results support Tish's hypothesis that seasonal ice cover supports a net atmospheric CO2 sink by capping outgassing when the surface waters are supersaturated in winter, but allowing drawdown during the productive, ice-free summer season.The European Subpolar Ocean Programme (ESOP) The mid-1990s were a period when the rate of deepwater formation in the central Greenland Sea was at a minimum, and from 1993 through 1995, the ESOP1 program conducted a comprehensive, seasonal study of the relationships between that slow deepwater formation rate, sea ice formation, and the carbon cycle (Deep-Sea Research special issue). Surprisingly, we found that although primary production was high, and the community was consistent with high f-ratios (Rey et al., 2000), biogenic export was extremely low, because of deep winter mixing which brought remineralized carbon back to the surface from as deep as 800 m (Miller et al., 1999; Noji et al., 2001). Nonetheless, the Greenland Sea was still a sink of atmospheric CO2 throughout the entire year, thanks to the low temperatures and long-term solubility pump activity (Skjelvan et al., 1999) |
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