Changes in the Arctic Ocean Carbon Cycle With Diminishing Ice Cover

Abstract

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 pCO ₂ 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 pCO ₂ measurements collected over a 6‐year period along a fixed cruise track in the Canada Basin. The measurements show that mean pCO ₂ levels are significantly higher during low ice years. The pCO ₂ increase is likely driven by ocean surface heating and uptake of atmospheric CO ₂ with large interannual variability in the contributions of these processes. These findings suggest that increased ice‐free periods will further increase sea surface pCO ₂, reducing the Canada Basin's current role as a net sink of atmospheric CO ₂.

Key Points

• The Arctic Ocean is losing ice cover at a rapid rate

• The loss of ice cover is leading to heating and uptake of atmospheric CO ₂, increasing sea surface CO ₂ levels

• Continued increase of sea surface CO ₂ will likely reduce the uptake of atmospheric CO ₂ in the future