THE RELATIONSHIP BETWEEN GLOBAL WARMING AND METHANE GAS HYDRATES IN THE EARTH

Temperature rise due to the increased concentration of trace atmospheric gases (TAG) in the atmosphere has the potential to cause decomposition of the methane hydrates in many parts of the earth. Methane gas hydrate reservoirs are located within permafrost or sediment underlying permafrost or below the ocean floor. The possibility of methane hydrate decomposition due to global warming is investigated by using a mathematical model based on heat conduction in single and composite media. Phase change within permafrost is taken into account. The temperature profiles and the critical time required for the onset of methane hydrate decomposition were computed and found to depend on the global warming scenario, the thermophysical properties of the earth and the required driving force for hydrate decomposition. The temperature at the top of a typical methane hydrate zone will begin to rise within the next 100 yr under a global temperature rise of 0.08-degrees-C/yr. However, methane hydrate decomposition will require a finite driving force and thus will occur later. Under a global temperature rise of 0.006-degrees-C/yr, these phenomena will be substantially delayed.