How quickly anthropogenic CO2 is being absorbed by the ocean remains one of the most critical and yet unanswered questions asked by climate researchers. Since the ocean is a major sink of anthropogenic CO2,an accurate estimate of the present oceanic uptake rate of anthropogenic CO2 is essential for reliable prediction of future atmospheric CO2. This number is difficult to pin down because the net airto‐sea CO2 flux is a small difference (about 2 Pg C yr−1, 1 Pg = 1015 g) between two huge fluxes—namely, the uptake and the release of CO2 at sea surface (each about 90 Pg C yr−1).