Once triggered, Methane Burps could result in runaway global warming the likes of which even the most pessimistic doomsayers aren't talking about.

"There are enormous quantities of naturally occurring greenhouse gasses trapped in ice-like structures in the cold northern muds and at the bottom of the seas. These ices, called clathrates, contain 3,000 times as much methane as is in the atmosphere. Methane is more than 20 times as strong a greenhouse gas as carbon dioxide. Now here's the scary part. A temperature increase of merely a few degrees would cause these gases to volatilize and "burp" into the atmosphere, which would further raise temperatures, which would release yet more methane, heating the Earth and seas further, and so on. There's 400 gigatons of methane locked in the frozen arctic tundra-enough to start this chain reaction-and the kind of warming the Arctic Council predicts is sufficient to melt the clathrates and release these greenhouse gases into the atmosphere."

An apocalyptic fantasy concocted by hysterical environmentalists? Unfortunately, no. Strong geologic evidence suggests something similar has happened at least twice before.

The most recent of these catastrophes occurred about 55 million years ago in what geologists call the Paleocene-Eocene Thermal Maximum (PETM), when methane burps caused rapid warming and massive die-offs, disrupting the climate for more than 100,000 years.

The granddaddy of these catastrophes occurred 251 million years ago, at the end of the Permian period, when a series of methane burps came close to wiping out all life on Earth.

More than 94 percent of the marine species present in the fossil record disappeared suddenly as oxygen levels plummeted and life teetered on the verge of extinction. Over the ensuing 500,000 years, a few species struggled to gain a foothold in the hostile environment. It took 20 million to 30 million years for even rudimentary coral reefs to re-establish themselves and for forests to regrow. In some areas, it took more than 100 million years for ecosystems to reach their former healthy diversity.

Geologist Michael J. Benton lays out the scientific evidence for this epochal tragedy in the book, When Life Nearly Died: The Greatest Mass Extinction of All Time. As with the PETM, greenhouse gases, mostly carbon dioxide from increased volcanic activity, warmed the earth and seas enough to release massive amounts of methane from these sensitive clathrates, setting off a runaway greenhouse effect.

The cause of all this havoc?

In both cases, a temperature increase of about 10.8 degrees Fahrenheit, about the upper range for the average global increase today's models predict can be expected from burning fossil fuels by 2100. But these models could be the tail wagging the dog since they don't add in the effect of burps from warming gas hydrates. Worse, the highest temperature increases from human greenhouse gas emissions will occur in the arctic regions-an area rich in these unstable clathrates.

If we trigger this runaway release of methane, there's no turning back. No do-overs. Once it starts, it's likely to play out all the way.

Humans appear to be capable of emitting carbon dioxide in quantities comparable to the volcanic activity that started these chain reactions. According to the US. Geological Survey, burning fossil fuels releases more than 150 times the amount of carbon dioxide emitted by volcanoes-the equivalent of nearly 17,000 additional volcanoes the size of Hawaii's Kilauea.

And that is the time bomb (so far) ignored.

How likely is it that humans will cause methane burps by burning fossil fuels? No one knows. But it is somewhere between possible and likely at this point, and it becomes more likely with each passing year that we fail to act.

So forget rising sea levels, melting ice caps, more intense storms, more floods, destruction of habitats and the extinction of polar bears. Forget warnings that global warming might turn some of the world's major agricultural areas into deserts and increase the range of tropical diseases, even though this is the stuff we're pretty sure will happen.

We can't afford to have the first sign of a failed energy policy be the mass extinction of life on Earth. We have to act now.”

In December 2004, the Baltimore Sun carried the above OpEd piece, entitled Methane Burps: Ticking Time Bomb, by John Atcheson, a geologist. His writing has also appeared in the Washington Post, the San Jose Mercury News and other papers.



April 17, 2008, SpiegelOnline in an article on the Methane threat, stated:

“Researchers have found alarming evidence that the frozen Arctic floor has started to thaw and release long-stored methane gas. The results could be a catastrophic warming of the earth, since methane is a far more potent greenhouse gas than carbon dioxide. It's always been a disturbing what-if scenario for climate researchers: Gas hydrates stored in the Arctic ocean floor -- hard clumps of ice and methane, conserved by freezing temperatures and high pressure -- could grow unstable and release massive amounts of methane into the atmosphere. Since methane is a potent greenhouse gas, more worrisome than carbon dioxide, the result would be a drastic acceleration of global warming. Until now this idea was mostly academic; scientists had warned that such a thing could happen. Now it seems more likely that it will.

In the permafrost bottom of the 200-meter-deep sea, enormous stores of gas hydrates lie dormant in mighty frozen layers of sediment. The carbon content of the ice-and-methane mixture here is estimated at 540 billion tons. "This submarine hydrate was considered stable until now," says the Russian biogeochemist Natalia Shakhova.

The permafrost has grown porous, says Shakhova, and already the shelf sea has become "a source of methane passing into the atmosphere." The Russian scientists have estimated what might happen when this Siberian permafrost-seal thaws completely and all the stored gas escapes. They believe the methane content of the planet's atmosphere would increase twelvefold. "The result would be catastrophic global warming," say the scientists. The greenhouse-gas potential of methane is 20 times that of carbon dioxide, as measured by the effects of a single molecule.

Shakhova and her colleagues gathered evidence for the loss of rigor in the frozen sea floor in a measuring campaign during the Siberian summer. The seawater proved to be "highly oversaturated with solute methane," reports Shakhova. In the air over the sea, greenhouse-gas content was measured in some places at five times normal values. "In helicopter flights over the delta of the Lena River, higher methane concentrations have been measured at altitudes as high as 1,800 meters," she says.

The methane climate bomb is also ticking on land: A few years ago researchers noticed higher concentrations of methane in northern Siberia. The Siberian permafrost is known as one of the tipping points for the earth's climate.

Data from offshore drilling in the region also suggest that the situation has grown critical. Climate change could give an additional push to these trends. "If the Arctic Sea ice continues to recede and the shelf becomes ice-free for extended periods, then the water in these flat areas will get much warmer," That could lead to a situation in which the temperature of the sea sediment rises above freezing, which would thaw the permafrost.

"We don't have any data on that -- those are just suspicions," Natalia Shakhova also passed on the question of whether to expect a gradual gas emission or an abrupt burst of large quantities of methane. "No one can say right now whether that will take years, decades or hundreds of years," she said. But one cannot rule out sudden methane emissions. They could happen at "any time."

For her part, Shakhova thinks researchers should be doing a lot more. She says too little is known about the fragile shelf sediment and the methane it stores, which could be explosive for the environment. "Actually," she says, ‘this is a wake-up call...’ “

Note: I have slightly edited both of the above articles. MG
 

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