Coastal Southern Ocean: A strong anthropogenic CO2 sink

Large‐scale estimates of the Southern Ocean CO 2 sink do not adequately resolve the fluxes associated with Antarctic continental shelves. Using a mechanistic three‐dimensional biogeochemical model of the Ross Sea, we show that Antarctic shelf waters are a strong sink for CO 2 due to high biological productivity, intense winds, high ventilation rates, and extensive winter sea ice cover. Net primary production (NPP) in these waters is ∼0.055 Pg C yr −1 . Some of this carbon sinks to depth, driving an influx of CO 2 of 20–50 g C m −2 yr −1 . Although currently unaccounted for, the total atmospheric CO 2 sink on the Ross Sea continental shelf of 0.013 Pg C yr −1 is equivalent to 27% of the most recent estimate of the CO 2 sink for the entire Southern Ocean. Given these results, these and other highly productive waters around the Antarctic continent need to be included in future budgets of anthropogenic CO 2 .