The present study is based on hourly samplings of wind speed, monthly sampling sessions of temperature, salin-ity, dissolved inorganic carbon, alkalinity, nutrients, primary productivity and vertical export in the outer sill re-gion (station GF3) of a sub-arctic SW Greenland fjord (Godthåbsfjord) through 2005–2010. Air–sea CO 2 fluxes varied at GF3 from c. −20 g C m − 2 month − 1 (uptake from the atmosphere) to 25 g C m − 2 month − 1 (release to the atmosphere) during 2005–10. The average annual air–sea CO 2 flux of −83 to −108 g C m − 2 yr − 1 was within the range of the local gross annual primary productivity of 76–106 g C m − 2 yr − 1 . Furthermore, the esti-mated vertical export of phytoplankton carbon to depths below 60 m of 38–89 g C m − 2 suggests that a large fraction of the mineralization (release of CO 2) occurs in deeper waters in the outer sill region of the fjord. How-ever, there was no statistically significant correlation between average annual gross primary production and an-nual air–sea flux during 2005–2010, which suggests that regulation of pCO 2 in the fjord is more complex. Despite three confined periods with supersaturated pCO 2 conditions in surface waters during 2005–2010, Godthåbsfjord can be considered as a strong sink (7.2 tons C month − 1 km − 2) for atmospheric CO 2 . In addition, measurements from Godthåbsfjord during the summer season showed that mixing between glacial meltwater and coastal water could explain a large part of the low pCO 2 -values observed in the innermost part of the fjord. Finally, a larger sur-vey confirmed the existence of very low pCO 2 conditions in nearshore and shelf waters around Southern Greenland.