The Arctic Ocean marine carbon cycle: evaluation of air-sea CO2 exchanges, ocean acidification impacts and potential feedbacks

• Published in: Biogeosciences
• Main Authors: Bates, N. R., Mathis, J. T.
• Format: Text
• Language: English
• Published: 2018
• Subjects: Arctic; Arctic Ocean; Climate change; Ocean acidification; Phytoplankton; Sea ice
• Online Access: https://doi.org/10.5194/bg-6-2433-2009; https://www.biogeosciences.net/6/2433/2009/

At present, although seasonal sea-ice cover mitigates atmosphere-ocean gas exchange, the Arctic Ocean takes up carbon dioxide (CO 2 ) on the order of −66 to −199 Tg C year −1 (10 12 g C), contributing 5–14% to the global balance of CO 2 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 CO 2 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 CO 2 by Arctic Ocean surface waters, although mitigated somewhat by surface warming in the Arctic. Thus, the capacity of the Arctic Ocean to uptake CO 2 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 CO 2 through air-sea gas exchange combine to decrease the calcium carbonate (CaCO 3 ) mineral saturation states (Ω) of seawater while seasonal phytoplankton primary production (PP) mitigates this effect. Biological amplification of ocean acidification effects in subsurface waters, due to the remineralization of organic matter, is likely to reduce the ability of many species to produce CaCO 3 shells or tests with profound implications for Arctic marine ecosystems