Modeling of oceanic gas hydrate instability and methane release in response to climate change
The behavior of oceanic methane hydrate deposits subjected to rapid temperature changes, like those predicted under future climate change scenarios, is poorly understood. To determine the fate of the carbon stored in these hydrates, we performed simulations of oceanic gas hydrate accumulations subjected to temperature changes at the seafloor and assessed the potential for methane release into the ocean. Our modeling analysis considered the properties of benthic sediments, the saturation and distribution of the hydrates, the ocean depth, the initial seafloor temperature, and for the first time, estimated the effect of benthic biogeochemical activity. The results show that shallow deposits - such as those found in arctic regions or in the Gulf of Mexico-can undergo rapid dissociation and produce significant methane fluxes of 2 to 13 mol/yr/sq m over a period of decades, and release up to 1,100 mol of methane per sq m of seafloor in a century. These fluxes may exceed the ability of the seafloor environment (via anaerobic oxidation of methane) to consume the released methane or sequester the carbon. These results will provide a source term to regional or global climate models in order to assess the coupling of gas hydrate deposits to changes in the global climate.
author list (cited authors)
Reagan, M. T., & Moridis, G. J.
complete list of authors
6th Gas Hydrates International Conference [ICGH] (Vancouver, British Columbia, 7/6-10/2008) Proceedings