Anthropogenic CO2 in the Atlantic Ocean

Abstract

The anthropogenic CO2 in the Atlantic Ocean is separated from the large natural variability of dissolved inorganic carbon using the method developed by Gruber et al. [1996]. Surface concentrations of anthropogenic CO2 are found to be highest in the tropical to subtropical regions and to decrease toward the high latitudes. They are very close to what is expected from thermodynamic considerations assuming that the surface ocean followed the atmospheric CO2 perturbation. Highest specific inventories (inventory per square meter) of anthropogenic CO2 occur in the subtropical convergence zones. Large differences exist between the North and South Atlantic high latitudes: In the North Atlantic, anthropogenic CO2 has already invaded deeply into the interior; north of 50°N it has even reached the bottom. By contrast, waters south of 50°S contain relatively little anthropogenic CO2, and hence specific inventories are very low. An anthropogenic CO2 inventory of about 22 ± 5 Gt C is estimated for the Atlantic north of the equator for 1982, and 18 ± 4 Gt C is estimated for the Atlantic south of the equator for 1989. The Princeton ocean biogeochemistry model predicts anthropogenic CO2 inventories of 20.0 Gt C (North Atlantic, 1982) and 17.7 Gt C (South Atlantic, 1989) for the same regions in good agreement with the observed inventories. Important differences exist on a more regional scale, associated with known deficiencies of the model.