The melting of vast stretches of permafrost in the Northern Hemisphere is expected to release large quantities of greenhouse gases into the atmosphere.
Now, a study from MIT published in Geophysical Research indicates that trapped methane may begin to bubble up from the ocean floor as global temperatures rise.
The ocean floor right now traps large quantities of methane in what is called the hydrate stability zone, where temperatures are low and ambient pressure is high. Methane molecules are actually trapped in a crystalline cage of frozen water. Warming could reduce the stability of the zone and release the gas.
Methane is 20 times more efficient than carbon dioxide in retaining heat in the atmosphere and methane concentrations now are higher than any other time period in the last 400,000 years. Approximately 60 percent of atmospheric methane comes from human activities – mining, cattle ranching, etc. – with 40 percent coming from natural sources. The danger, of course, is that humans are now accelerating the natural release.
"The sediment conditions under which this mechanism for gas migration dominates, such as when you have a very fine-grained mud, are pervasive in much of the ocean as well as in some permafrost regions,” said lead author Ruben Juanes, the ARCO Assistant Professor in Energy Studies in the Department of Civil and Environmental Engineering, in a prepared statement."