Known frozen methane sites around the world: a nasty climatic surprise in store? (Pic: Oak Ridge National Lab)
Anna Salleh - ABC Science Online
Vast stockpiles of frozen methane on the seafloor are more unstable than previously thought, and their sudden release may have been linked to global warming in the past.
Led by Dr Kai-Uwe Hinrichs of the Woods Hole Oceanographic Institution in Massachusetts, USA, the new evidence is published in this week's issue of Science.
The researchers examined the by-products of ancient methane-using bacteria in sediments of the Santa Barbara Basin, off the coast of California. They found evidence that methane trapped in ice crystals (known as methane hydrates) on the seabed was released into the water 44,000 years ago - at the same time there was a rapid, but as yet unexplained, rise in global temperatures.
Methane is a potent greenhouse gas, about 10 times more powerful than carbon dioxide. Scientists estimate that approximately 3,000 times the volume of methane in the atmosphere is currently trapped in hydrates at the bottom of the sea.
While conclusive proof is still lacking that the seabed methane released into ocean sediments 44,000 years ago reached the atmosphere, the fact that the hydrates are not as stable as scientists believed raises the possibility that they could be a climatic time-bomb in the future.
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