For point of reference, the average temperature of the Earth (atmosphere, land and top layer of the ocean) in 2004 is around 60°F. The methane hydrate release projected here would raise the temperature to around 90°F or more. Such high temperatures would undoubtedly destabilize all of the other methane hydrates in the ocean and arctic permafrost, some 10,000 GtC or 620,000 GtC equivalent as carbon dioxide. This would have the impact of 78,000 years worth of GHG warming over a few decades. The temperatures reached and sustained would most likely cause a rapid die off in ocean phytoplankton and other sea life as well as most land plants and animals, including humans. The result would be a mass extinction and mark a major transition point in the Earth’s geological history.
Although a 1000 or 10,000 GtC methane release in one year or over several decades is very unlikely, a 4 GtC release is entirely plausible. Even if the feedback mechanisms that were operative 15,000 years ago became partly active, the outcome could be just as disastrous as the scenario outlined above.
Gaskill said that if any massive releases of methane from methane hydrates were to occur, attempts should be made to ignite and burn the methane gas at the ocean’s surface. By converting the methane to carbon dioxide, the threat of abrupt climate change is reduced by a factor of 62, to less than one-years worth of GHG emissions. Even if the mitigation effort is only partly successful, say 75% is converted to carbon dioxide, the remaining methane, equivalent to an 8-year pulse of all present day GHG emissions in a single year might still spell trouble, but it would be far preferable to the nightmare scenarios outlined above.
Combustion could be accomplished by aerial release and ignition of distillate fuel over the area where the methane is entering the atmosphere. There are several potential problems with this approach. The area to be covered may be too large to effectively treat in this way. Advection may also make continuous burning difficult. Dr. MacCracken pointed out that the methane level in the air at the surface might be too low to ignite. This would, of course depend on how fast the gas is being released.
Regardless, the potential for massive methane release from sediments represents such a significant threat that emergency mitigation plans like the one suggested here need to be prepared. The Methane Hydrate Research and Development Act of 2000, Public Law 106-193 does not address such catastrophic scenarios and we are unaware of anyone working on such plans.
