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A new paper published appearing Thursday in the prestigious scientific journal Nature presents the worst-case scenario for runaway climate change that could leave the Earth entirely ice-free within a generation.

If global temperatures continue to rise, massive amounts of methane gas could be released from the 10,000 gigaton reserves of frozen methane that are currently locked in the world's deep oceans and permafrost. Passing this climate tipping point would result in global warming that would be far worse and more rapid than scientists' current estimates.

The new paper suggests that exactly this type of cascading release of methane reserves rapidly warmed the Earth 635 million years ago, replacing an Ice Age with a period of tropical heat. The study's lead author suggests it could happen again, and fast -- not over thousands or millions of years, but possibly within a century.

"This is a major concern because it’s possible that only a little warming can unleash this trapped methane," Martin Kennedy, a professor at UC Riverside, said in a release. "Unzippering the methane reservoir could potentially warm the Earth tens of degrees, and the mechanism could be geologically very rapid."

Methane is 25 times more potent than carbon dioxide as a greenhouse gas. And the frozen reserve is twice as large, by volume, as the world's known fossil fuel reserves.

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Source.


Here is the original USGS report which contains a PDF poster with lots of detail. It is necessary to enlarge to poster to see all of the details.


Non-scalable poster of clathrate distribution.


Edited by Hill (06/01/08 08:57 PM)

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Chien-Liu Ping and a team of researchers at the University of Alaska, Fairbanks spent the last 13 years meticulously sampling tundra soils across North America. In a study published this week in the journal Nature Geoscience, they estimate there may be almost 100 billion tons of carbon in the first meter of soil alone.

That's equivalent to about a quarter of the amount currently in Earth's atmosphere, or 10 years' worth of global emissions from human activity.

It also nearly doubles previous estimates of carbon content in Arctic soil. Despite decades of work, such approximations are rough at best, because land in the far North is vast, remote, and inhospitably cold. Even in the height of summer, soil scientists can rarely dig deeper than 50 centimeters before they hit rock-solid permafrost.

But worst-case scenario climate projections from the Intergovernmental Panel on Climate Change (IPCC) suggest Arctic temperatures could climb as much as 6 degrees centigrade by the end of the century.

If that happens, the Arctic region, which has already shown signs of thawing, will change dramatically. Already scientists have begun seeing areas where permafrost tundra has melted into muddy bogs called 'thermokarsts.' In other places, steep hillsides, no longer supported by rigid ice crystals, are giving way in landslides.

As the land melts bacteria intrude, decomposing the plant matter that has built up over thousands of years. They release methane and carbon dioxide into the air as byproducts, gases that warm the planet by trapping heat energy from the sun.

"Permafrost temperatures in Alaska have gone up about 1 degree Centigrade over the last 50 years," Ping said, pushing soils to within a fraction of a degree of freezing temperature. "In Russia, they've been monitoring permafrost for over a century. It has warmed 2 degrees Centigrade, so almost 5 degrees Fahrenheit."

It's not all bad news though. The warmer temperatures should allow plants to grow vigorously, and they can suck up huge amounts of carbon out from the atmosphere through photosynthesis -- perhaps even enough to cancel out greenhouse gas emissions from the soil.

In fact, many scientists say the jury is still out on whether or not the thawing Arctic could quicken the pace of global warming.

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Arctic scientists discover new global warming threat as melting permafrost releases millions of tons of a gas 20 times more damaging than carbon dioxide

The first evidence that millions of tons of a greenhouse gas 20 times more potent than carbon dioxide is being released into the atmosphere from beneath the Arctic seabed has been discovered by scientists.

The Independent has been passed details of preliminary findings suggesting that massive deposits of sub-sea methane are bubbling to the surface as the Arctic region becomes warmer and its ice retreats.


Preliminary findings suggest that massive deposits of subsea methane are bubbling to the surface as the Arctic region becomes warmer and its ice retreats



Underground stores of methane are important because scientists believe their sudden release has in the past been responsible for rapid increases in global temperatures, dramatic changes to the climate, and even the mass extinction of species. Scientists aboard a research ship that has sailed the entire length of Russia's northern coast have discovered intense concentrations of methane – sometimes at up to 100 times background levels – over several areas covering thousands of square miles of the Siberian continental shelf.


In the past few days, the researchers have seen areas of sea foaming with gas bubbling up through "methane chimneys" rising from the sea floor. They believe that the sub-sea layer of permafrost, which has acted like a "lid" to prevent the gas from escaping, has melted away to allow methane to rise from underground deposits formed before the last ice age.


They have warned that this is likely to be linked with the rapid warming that the region has experienced in recent years.


Methane is about 20 times more powerful as a greenhouse gas than carbon dioxide and many scientists fear that its release could accelerate global warming in a giant positive feedback where more atmospheric methane causes higher temperatures, leading to further permafrost melting and the release of yet more methane.


The amount of methane stored beneath the Arctic is calculated to be greater than the total amount of carbon locked up in global coal reserves so there is intense interest in the stability of these deposits as the region warms at a faster rate than other places on earth.


Orjan Gustafsson of Stockholm University in Sweden, one of the leaders of the expedition, described the scale of the methane emissions in an email exchange sent from the Russian research ship Jacob Smirnitskyi.


"We had a hectic finishing of the sampling programme yesterday and this past night," said Dr Gustafsson. "An extensive area of intense methane release was found. At earlier sites we had found elevated levels of dissolved methane. Yesterday, for the first time, we documented a field where the release was so intense that the methane did not have time to dissolve into the seawater but was rising as methane bubbles to the sea surface. These 'methane chimneys' were documented on echo sounder and with seismic [instruments]."


At some locations, methane concentrations reached 100 times background levels. These anomalies have been seen in the East Siberian Sea and the Laptev Sea, covering several tens of thousands of square kilometres, amounting to millions of tons of methane, said Dr Gustafsson. "This may be of the same magnitude as presently estimated from the global ocean," he said. "Nobody knows how many more such areas exist on the extensive East Siberian continental shelves.


"The conventional thought has been that the permafrost 'lid' on the sub-sea sediments on the Siberian shelf should cap and hold the massive reservoirs of shallow methane deposits in place. The growing evidence for release of methane in this inaccessible region may suggest that the permafrost lid is starting to get perforated and thus leak methane... The permafrost now has small holes. We have found elevated levels of methane above the water surface and even more in the water just below. It is obvious that the source is the seabed."


The preliminary findings of the International Siberian Shelf Study 2008, being prepared for publication by the American Geophysical Union, are being overseen by Igor Semiletov of the Far-Eastern branch of the Russian Academy of Sciences. Since 1994, he has led about 10 expeditions in the Laptev Sea but during the 1990s he did not detect any elevated levels of methane. However, since 2003 he reported a rising number of methane "hotspots", which have now been confirmed using more sensitive instruments on board the Jacob Smirnitskyi.


Dr Semiletov has suggested several possible reasons why methane is now being released from the Arctic, including the rising volume of relatively warmer water being discharged from Siberia's rivers due to the melting of the permafrost on the land.


The Arctic region as a whole has seen a 4C rise in average temperatures over recent decades and a dramatic decline in the area of the Arctic Ocean covered by summer sea ice. Many scientists fear that the loss of sea ice could accelerate the warming trend because open ocean soaks up more heat from the sun than the reflective surface of an ice-covered sea.

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The Independent

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