Methane Hydrate Eruptions

* Huge reservoirs of methane trapped beneath the ocean floor rapidly escaped during prehistoric global warming and depleted much of the sea's oxygen, according to new research into why many forms of life suddenly vanished 183 million years ago. The findings, reported in the journal Nature, shed new light not only on the disappearance of as many as 80 percent of some deep-sea species but also a process suspected in other prehistoric mass extinctions
* 55 million years ago a series of methane gas blasts may have choked the atmosphere with greenhouse gases at a pace similar to that at which the burning of fossil fuels pumps them into the air today.
* At the end of an epoch of time known as the Paleocene, temperatures in the deep ocean soared by about six degrees Celsius. This worldwide heat wave killed off a plethora of microscopic deep-sea creatures and produced a bizarre spike in the record of carbon isotopes. 55 percent of the species of deep-sea forams had disappeared from the fossil record in a blink of an eye in geologic time—less than 10,000 years. Five years ago paleoceanographer Gerald ("Jerry") Dickens of James Cook University Of in Australia proposed that a belch of seafloor methane—a greenhouse gas with almost 30 times the heat-trapping ability of carbon dioxide—caused the shock.

* Methane hydrate is formed beneath the sea floor when algae from the surface dies and sinks. Normally a gas, the methane is locked in an ice-like state but is susceptible to changes in pressure and temperature.
* Paleontologists have long known that the dawning of the Eocene Epoch 55 million years ago was the beginning of the modern era of mammals - with humans to become the most successful of the new creatures - but they didn't know what caused it. ''It's amazing that changes in the deep oceans could cause the dispersal of new mammals across the land,'' said William Clyde, a specialist of mammalian evolution at the University of New Hampshire. ''It's amazing there are all these connections.''





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1) Vast quantities of methane were stored as frozen gas hydrate in the upper 1,500 feet of continental slope sediments.

2) MICROSCOPIC CREATURES, including this foraminifer called Stensioina beccariiforrnis, died in droves when their ocean-bottom homes heated up during a worldwide climate fever about 55 million years ago.



Historic global warming linked to methane release

By John Roach

An intense period of global warming about 55.5 million years ago has been linked to a massive release of methane, an event that killed many deep-sea species and enabled terrestrial animals to flourish, according to an article in today's issue of the journal Science.

The warming, known as the "latest Paleocene thermal maximum," occurred over a 10,000 to 20,000-year interval and corresponds to the appearance of numerous mammals (including primates) and the extinction or temporary disappearance of many deep-sea species.

The link between this warming period and the methane release is based on analysis of a sediment core taken from the ocean floor and is the first tangible evidence of a long held hypothesis, said Dorothy Pak, a researcher at the University of California, Santa Barbara, and co-author of the study.

According to the hypothesis, vast quantities of methane were stored as frozen gas hydrate in the upper 1,500 feet of continental slope sediments before the latest Paleocene thermal maximum, during which ocean waters warmed by 7 to 14 degrees.


Mass extinction traced to oceanic methane burp

Oxford scientists studied fossil wood deposits and identified a signal that they say indicates an unusual level of light carbon in the Earth's atmosphere.

"It's a question of trying to identify what the source of the light carbon would be," Hesselbo said. "The best explanation in this case is that it comes from methane -- methane hydrate from ocean margin sediment."

The researchers believe massive volcanic eruptions during the Jurassic period initiated global warming by spewing carbon dioxide and other greenhouse gases into the atmosphere. Deep-sea currents also were affected.

Methane, freed from its suboceanic cage by warmer water, then used the oxygen in the water or atmosphere to form carbon dioxide. In either case, it would have accelerated global warming.

"A number of important fossil groups disappeared at exactly that time," Hesselbo said. "The extinction and the association with the lack of oxygen has been fairly well established, but the association with methane release is something that hasn't been realized before."
Bottom Feeders affected the most

Hardest hit were bottom-feeding clam-like organisms known as bivalves: An estimated 80 percent of the species disappeared. Others affected included ostacods, belemnites and some marine plants.

The researchers believe the event took place over a period of 5,000 years -- a blink in geologic time. The release was estimated to be 20 percent of the present-day 14,000 billion tons of gas hydrate on the sea floor.