Abstract. Assessments of future climate-warming-induced seafloor methane (CH4)
release rarely include anaerobic oxidation of methane (AOM) within the
sediments. Considering that more than 90 % of the CH4 produced in
ocean sediments today is consumed by AOM, this may result in substantial
overestimations of future seafloor CH4 release. Here, we integrate a
fully coupled AOM module with a numerical hydrate model to investigate under
what conditions rapid release of CH4 can bypass AOM and result in
significant fluxes to the ocean and atmosphere. We run a number of different
model simulations for different permeabilities and maximum AOM rates. In all
simulations, a future climate warming scenario is simulated by imposing a
linear seafloor temperature increase of 3 ∘C over the first 100 years.
The results presented in this study should be seen as a first step
towards understanding AOM dynamics in relation to climate change and hydrate
dissociation. Although the model is somewhat poorly constrained, our results
indicate that vertical CH4 migration through hydraulic fractures can
result in low AOM efficiencies. Fracture flow is the predicted mode of
methane transport under warming-induced dissociation of hydrates on upper
continental slopes. Therefore, in a future climate warming scenario, AOM
might not significantly reduce methane release from marine sediments.
Can anaerobic oxidation of methane prevent seafloor gas escape in a warming climate?
