SENSITIVITY OF MARINE METHANE HYDRATES TO FUTURE OCEAN WARMING

Changes in the global hydrate stability zone are predicted in response to future ocean warming resulting from elevated atmospheric carbon dioxide concentrations. I address this issue using the UVic Earth System Climate Model coupled to a simple methane hydrate stability model to simulate spatial and temporal changes of the global marine methane hydrate stability zone. Modeled temperature changes at the seafloor due to climate change scenarios are diffused into continental shelf sediment columns, shifting the base of the hydrate stability zone. The global hydrate stability zone volume decreases significantly over timescales of 1000 to 10000 years after the initial atmospheric carbon dioxide increase. This timescale is largely controlled by sediment thermal diffusivity and the geothermal gradient. Several regions of total hydrate destabilization are modeled; these are regions in which hydrate-derived carbon may most easily enter the exogenic carbon cycle. Conservative estimates of potential carbon input to the exogenic carbon cycle from such regions are of the same order of magnitude as current annual anthropogenic carbon emissions.