Modeling the Recent Changes in the Arctic Ocean CO2Sink (2006–2013)

Abstract

The Arctic Ocean (AO) and its associated marginal seas have recently experienced rapid climate and environmental changes, most notably sea‐ice area (SIA) loss and warming potentially impacting its uptake of carbon dioxide (CO2). We used the state‐of‐the‐art ECCO2‐Darwin coupled ocean‐biogeochemistry model to simulate the 2006–2013 period and investigate the impact of changing SIA on the CO2uptake of the AO. We find that the mean annual CO2sink of the AO is 153 ± 14 TgC a−1and the CO2sink decreased at a rate of 3.6 TgC a−1even though SIA decreased by 8 × 104 km2 a−1over the same period. Extreme SIA loss in 2007 resulted in a 185.4 TgC CO2sink, an increase ∼20% over the 2006–2013 mean. In contrast, extreme SIA loss of 2012 resulted in a CO2sink of the AO of only 146.3 TgC due to two main factors: (1) increased both wind speed and stratification in the Eastern Siberian Sea absorbing less CO2and (2) decreased primary production and area of air‐sea gas exchange in the Chukchi and Nordic Seas. Our model captures a trend of decreasing CO2sink in most of the Chukchi Sea during fall but does not show the changes in winter CO2sink in the Nordic and Barents Seas as previous independent studies have suggested. Our results indicate that future AO‐atmosphere CO2exchange will be determined by complex interplay of SIA and other environmental drivers.