The greatest temperature rise due to global warming is expected to occur in the Arctic. This possibility threatens the thermodynamic stability of the in-situ methane hydrates Which have been identified there. In this work, the possibility of hydrate decomposition in three methane hydrate fields in the Arctic due to three climate change scenarios is evaluated. The time required for the temperature to exceed a certain value in the upper limit of the hydrate stability zone causing hydrate decomposition will be calculated. Under the worst case global warming scenario, the required time for beginning of gas hydrate de-stabilization ranges from a few decades to several hundred years.
Methane is known to be among a number of molecules that can physically combine with water and form solid gas hydrates (van der Waals and Platteeuw, 1959; Davidson, 1973; Makogon, 1981; Berecz and Balla-Achs, 1983; Sloan, 1989). Suitable geologic and environmental conditions enabled natural gas, containing mostly methane, to form hydrates in the earth from the present to several million years ago. These hydrates became recognized during the last 25 years (Katz, 1971; Bily and Dick, 1974, Holder et al. 1976; Makogon, 1981). Hydrates occur within and below the permafrost in Arctic regions and below ocean floors in many parts of the world. Estimates of the amount of methane in hydrates vary (Kvenvolden, 1988a; 1988b; Sloan, 1989; Finley and Krason, 1990), but a reasonable figure is 1016 m3 of methane. Such a large amount of methane justifies efforts to find economic recovery schemes (Kamath and Godpole, 1987; Sloan, 1989; Yousif et al. 1991). The in-situ hydrates may also be a source of methane that could be released in the atmosphere because they may decompose into water and methane if their temperature exceeds the equilibrium formation temperature.
