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Modeling of Oceanic Gas Hydrate Instability and Methane Release in Response to Climate Change.

DE2008935357

Publication Date	2008
Personal Author	Reagan, M. T.; Moridis, G. J.
Page Count	9
Abstract	Paleooceanographic evidence has been used to postulate that methane from oceanic hydrates may have had a significant role in regulating global climate, implicating global oceanic deposits of methane gas hydrate as the main culprit in instances of rapid climate change that have occurred in the past. However, the behavior of contemporary 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/m(sup 2) over a period of decades, and release up to 1,100 mol of methane per m(sup 2) 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.
Keywords	Oceans Methane Gases Hydrates Arctic regions Climate models Carbon Saturation Distribution Sediments Simulation Instability Dissociation
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Lawrence Berkeley National Lab., CA. Earth Sciences Division.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200903
Contract Number	DE-AC02-05CH11231

Modeling of Oceanic Gas Hydrate Instability and Methane Release in Response to Climate Change.

Modeling of Oceanic Gas Hydrate Instability and Methane Release in Response to Climate Change.
DE2008935357

Publication Date	2008
Personal Author	Reagan, M. T.; Moridis, G. J.
Page Count	9
Abstract	Paleooceanographic evidence has been used to postulate that methane from oceanic hydrates may have had a significant role in regulating global climate, implicating global oceanic deposits of methane gas hydrate as the main culprit in instances of rapid climate change that have occurred in the past. However, the behavior of contemporary 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/m(sup 2) over a period of decades, and release up to 1,100 mol of methane per m(sup 2) 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.
Keywords	Oceans Methane Gases Hydrates Arctic regions Climate models Carbon Saturation Distribution Sediments Simulation Instability Dissociation
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Lawrence Berkeley National Lab., CA. Earth Sciences Division.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200903
Contract Number	DE-AC02-05CH11231