Fig. 5.

Ebullitive and total CH₄ emissions. a Modeled transfer efficiency of CH₄ in bubbles from the seafloor to surface ocean, for 2 and 8 mm diameter bubbles, and integrated across a characteristic bubble size spectrum (Supplementary Fig. 7). Diamond and circle points represent the mean transfer efficiency for bubbles released uniformly between 0–100 and 0–200 m, respectively, and gray shading marks the range of 11–17% bounded by these cases. b Probability density functions for total oceanic CH₄ emissions, combining the distribution for diffusive fluxes (Fig. 4b) with two uniform probability distributions for ebullitive emissions that are obtained by applying 11–17% transfer efficiency to seafloor ebullition rates of 35 and 18–48 Tg yr⁻¹. Dark and light gray shading mark the likely range (10–90th percentiles) for the two estimates