Five of the most recent observational methods to estimate anthropogenic CO2 (C-ant) are applied to a high-quality dataset from five representative sections of the Atlantic Ocean extending from the Arctic to the Antarctic. Between latitudes 60 degrees N-40 degrees S all methods give similar spatial distributions and magnitude of C-ant. However, discrepancies are found in some regions, in particular in the Southern Ocean and Nordic Seas. The differences in the Southern Ocean have a significant impact on the anthropogenic carbon inventories. The calculated total inventories of C-ant for the Atlantic referred to 1994 vary from 48 to 67 Pg (10(15) g) of carbon, with an average of 54 +/- 8 Pg C, which is higher than previous estimates. These results, both the detailed C-ant distributions and extrapolated inventories, will help to evaluate biogeochemical ocean models and coupled climate-carbon models.