Large-scale Simulation of Oceanic Gas Hydrate Dissociation in Response to Climate Change

Vast quantities of methane are trapped in oceanic hydrate deposits, and there is concern that a rise in the ocean temperature will induce dissociation of these hydrate accumulations, potentially releasing large amounts of carbon into the atmosphere. Because methane is a powerful greenhouse gas, such a release could have dramatic climatic consequences. The recent discovery of active methane gas venting along the landward limit of the gas hydrate stability zone (GHSZ) on the shallow continental slope west of Svalbard suggests that this process may already have begun, but the source of the methane has not been determined. This study performs a 2D simulation of hydrate dissociation in conditions representative of the Svalbard margin to assess whether such hydrates could be responsible for in the observed gas release. The results show that shallow, low-saturation hydrate deposits, if subjected to recent measured or predicted temperature changes at the seafloor, can release quantities of methane at the magnitudes recorded, and that the releases will be localized near the landward limit of the top of the GHSZ as observed. Both gradual and rapid warming is simulated, and localized gas release is observed for both cases. These suggest that hydrate dissociation and methane release as a result of climate change may be a real phenomenon, and that it already may be occurring.