A 35% increase in the ocean CO₂ uptake estimate by correcting for two temperature effects

The oceans are a major sink for carbon dioxide (CO₂) and are estimated to take up roughly a quarter of the anthropogenic CO₂ emissions. A recent study suggested a substantial increase (∼50% or 0.9 Pg C yr⁻¹; Watson et al., 2020, Nat. Commun.) in the global ocean CO₂ uptake estimate by considering two temperature effects (the ship engine-induced warm bias and the cool skin effect). However, a new study led by Yuanxu Dong and Dorothee Bakker from the University of East Anglia, published in Global Biogeochemical Cycles, suggests that this previous study might have overestimated the temperature flux corrections. By re-visiting these two temperature effects using updated datasets and methods, the authors show that the global net ocean CO₂ uptake estimate increased by ∼35% on average from 1982 to 2020. The temperature-revised CO₂ flux sits between estimates of ocean CO₂ uptake from surface ocean CO₂ observations and from the independent ocean carbon inventory (Gruber et al., 2019, Science).

Reference: Dong, Y., Bakker, D.C.E., Bell, T.G., et al. (2022). Update on the temperature corrections of global air-sea CO₂ flux estimates. Glob. Biogeochem. Cycle, 36, e2022GB007360. https://doi.org/10.1029/2022GB007360