Bubble-Mediated Asymmetric Transfer Reveals a Larger Ocean CO2 Sink

The ocean plays a key role in regulating Earth's climate by absorbing a large fraction of anthropogenic carbon dioxided (CO₂). Air-sea gas exchange occurs both at the interface and via bubbles generated by breaking waves. This exchange process has traditionally been treated as symmetric, assuming gas enters and leaves the ocean at the same rate. Here, we use direct field observations to show that bubble-mediated exchange is asymmetric, favoring CO₂ invasion (See figure below). This arises because pressure beneath the sea surface compresses bubbles, enhancing CO₂ transfer into seawater. Incorporating this bubble process into the bulk flux formulation suggests that global ocean CO₂ uptake may be underestimated by 0.3–0.4 Pg C/yr, roughly a 15 % increase over recent decades.

Reference: Dong, Y., Yang, M., Bell, T.G., et al. (2025). Asymmetric bubblemediated gas transfer enhances global ocean CO₂ uptake. Nat. Commun., 16, 10595. https://doi.org/10.1038/s41467-025-66652-5