Air-sea flux of anthropogenic carbon dioxide in the North Atlantic

Abstract

A conceptual advective model is employed to evaluate the mechanism of oceanic uptake of anthropogenic CO2 in the North Atlantic, and its sensitivity to climate change. Given initial carbon system parameters, and climatological wind speed, sea surface temperatures, sea surface salinities, and mixed layer depths, the air-sea exchange of CO2 in a water parcel flowing from low to high latitudes is calculated using an iterative procedure. The calculations are carried out under present and preindustrial atmospheric conditions, with the difference assigned to be air-sea flux of anthropogenic CO2. The result reveals a flux of anthropogenic CO2 into the surface water at latitudes south of ∼50 oN and a flux out of the surface water at higher latitudes. The quantitative air-sea flux of anthropogenic CO2 is very sensitive to several factors, important ones being the flow speed and thickness of the north flowing surface water. This suggests a strong feedback on anthropogenic CO2 uptake in the North Atlantic if climate change affects the strength of the oceanic circulation.