Glob. Biogeochem. Cycles http://doi.org/p27 (2013)
Sea ice cover in the Arctic Ocean has declined significantly in the past three decades. Model simulations suggest that the biological draw-down of surface-water CO2 to depth has increased as a result.
Manfredi Manizza of the Scripps Institution of Oceanography, USA, and colleagues assessed temporal changes in Arctic Ocean carbon uptake between 1996 and 2007, using a regional physical–biogeochemical model forced with reanalysis data. According to their simulations, the Arctic Ocean took up an additional 1.4 Tg of carbon per year over this period. A rise in phytoplankton productivity in the surface waters of the Laptev, East Siberian, Chukchi and Beaufort seas was responsible for the increase in carbon uptake. In contrast, net carbon uptake declined in the Barents Sea, where a warming-induced outgassing of surface-water CO2 countered the rise in primary production.
The findings suggest that the continued decline of Arctic sea ice cover could be accompanied by a rise in the oceanic uptake of carbon dioxide, although uncertainties in the response of physical, chemical and biological processes to sea ice loss hinder reliable predictions at this stage.