Climate change and methane

Abstract

Climate change and methaneSIR-Among the many explanations of the rapid climate changes that occurred at the end of the last glaciation is the suggestion that warming was initially driven by methane emitted from northern gas fields and gas hydrates, during a time of rising insolation".This explanation is compatible with the recent reports' 7, that warming took place in two abrupt pulses, 13,000 and 10,500 years ago.The 'methane-led' account of deglaciation invokes the strong positive feedback that would follow evasion of gas stored at high latitude during glaciation.In the model, increasing insolation destabilizes methane that accumulated during glaciation.The methane became trapped in hydrate when upward seepage was blocked by low temperatures, in areas such as the giant West Siberian fields, north-west North America, or the southern North Sea.Methane is incrementally a much more effective greenhouse gas than CO,, and the rupture of one or two large gas pools (for example, 10''-" g CHJ, or emission from an area of permafrost, could have initiated a thermal runaway, liberating more gas (possibly 10" g CH, per yr) and rapidly raising planetary temperatures.The liberated gas would have been converted to CO, in the air, and the atmospheric warming would have induced oceanic warming and discharge of further CO,, thus replenishing the inventories of carbon both on land and in the air.