Changes in the Arctic Ocean Carbon Cycle With Diminishing Ice Cover.

Less than three decades ago only a small fraction of the Arctic Ocean (AO) was ice free and then only for short periods. The ice cover kept sea surface CO at levels lower relative to other ocean basins that have been exposed year round to ever increasing atmospheric levels. In this study, we evaluate sea surface CO measurements collected over a 6-year period along a fixed cruise track in the Canada Basin. The measurements show that mean CO levels are significantly higher during low ice years. The CO increase is likely driven by ocean surface heating and uptake of atmospheric CO with large interannual variability in the contributions of these processes. These findings suggest that increased ice-free periods will further increase sea surface CO, reducing the Canada Basin's current role as a net sink of atmospheric CO.