Improved Air-Sea CO2 Flux Estimates from SailboatMeasurements

Remote ocean regions such as the Southern Ocean are highly undersampled, causing substantial uncertainties in estimates of the ocean CO₂ uptake. Citizen science sailboats navigate these remote waters, collecting CO₂ data along the way. In Science Advances, Behncke et al. use a biogeochemical model as a reference "truth" and a neural network for gap-filling to show how additional sailboat data can improve CO₂ sink estimates. Mimicking current real-world sampling underestimates the ocean carbon sink, and adding all sailboat tracks available up to 2021 does not significantly change this. However, including data from two additional circumnavigations increases the estimated sink, particularly between 40°S and 60°S, thereby improving the estimate – even in the presence of potential measurement uncertainties – while also showing a continued overestimation of the Southern Ocean sink trend. Sustained, multidecadal observational efforts are essential to further improve these estimates.

Reference: Behncke, J., Ilyina, T., Chegini, F. & Landschützer, P. (2026). Improved air-sea CO2 flux estimates from sailboat measurements. Sci. Adv, 12(2), eadz1502. https://doi.org/10.1126/sciadv.adz1502