Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 6 11 2009 10.5194/bg-6-2433-2009 http://www.biogeosciences.net/6/2433/2009/ http://www.biogeosciences.net/6/2433/2009/bg-6-2433-2009.html http://www.biogeosciences.net/6/2433/2009/bg-6-2433-2009.pdf 2433 2459 2009-11-05 The Arctic Ocean marine carbon cycle: evaluation of air-sea CO₂ exchanges, ocean acidification impacts and potential feedbacks N. R. Bates nick.bates@bios.edu J. T. Mathis Bermuda Institute of Ocean Sciences, Ferry Reach, Bermuda School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, Alaska, USA At present, although seasonal sea-ice cover mitigates atmosphere-ocean gas exchange, the Arctic Ocean takes up carbon dioxide (CO₂) on the order of −66 to −199 Tg C year^−1 (10¹² g C), contributing 5–14% to the global balance of CO₂ sinks and sources. Because of this, the Arctic Ocean has an important influence on the global carbon cycle, with the marine carbon cycle and atmosphere-ocean CO₂ exchanges sensitive to Arctic Ocean and global climate change feedbacks. In the near-term, further sea-ice loss and increases in phytoplankton growth rates are expected to increase the uptake of CO₂ by Arctic Ocean surface waters, although mitigated somewhat by surface warming in the Arctic. Thus, the capacity of the Arctic Ocean to uptake CO₂ is expected to alter in response to environmental changes driven largely by climate. These changes are likely to continue to modify the physics, biogeochemistry, and ecology of the Arctic Ocean in ways that are not yet fully understood. In surface waters, sea-ice melt, river runoff, cooling and uptake of CO₂ through air-sea gas exchange combine to decrease the calcium carbonate (CaCO₃) mineral saturation states (Ω) of seawater while seasonal phytoplankton primary production (PP) mitigates this effect. 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