New Study: Methane Hydrate may be key to climate change

Nature ^ | January 8, 2004 | MATTHEW J. HORNBACH, DEMIAN M. SAFFER & W. STEVEN HOLBROOK

[alloysteel]

Palaeoceanographic data have been used to suggest that methane hydrates play a significant role in global climate change. The mechanism by which methane is released during periods of global warming is, however, poorly understood. In particular, the size and role of the free-gas zone below gas-hydrate provinces remain relatively unconstrained, largely because the base of the free-gas zone is not a phase boundary and has thus defied systematic description. Here we evaluate the possibility that the maximum thickness of an interconnected free-gas zone is mechanically regulated by valving caused by fault slip in overlying sediments. Our results suggest that a critical gas column exists below most hydrate provinces in basin settings, implying that these provinces are poised for mechanical failure and are therefore highly sensitive to changes in ambient conditions. We estimate that the global free-gas reservoir may contain from one-sixth to two-thirds of the total methane trapped in hydrate. If gas accumulations are critically thick along passive continental slopes, we calculate that a 5 °C temperature increase at the sea floor could result in a release of 2,000 Gt of methane from the free-gas zone, offering a mechanism for rapid methane release during global warming events.

To demystify what the above says:

http://www.newswise.com/articles/view/502756/

Scientists at the University of Wyoming may have discovered how massive amounts of carbon enter the atmosphere during periods of global warming.

In a paper published Jan. 8 in the journal Nature, UW Department of Geology and Geophysics graduate student Matthew Hornbach and professors Demian Saffer and Steve Holbrook propose that the source of the carbon is methane gas found beneath methane hydrate -- an ice-like substance consisting of frozen methane and water. Methane hydrate exists in vast quantities beneath the ocean floor and is believed to constitute the largest reservoir of organic carbon on Earth.

Hornbach, Saffer and Holbrook contend that a rise in ocean temperatures can convert the methane hydrate into methane gas. "Since methane is a greenhouse gas, substantial amounts of it released from beneath these hydrate deposits can contribute to global warming," Hornbach says.

For decades climate researchers have recognized that global warming events correspond with rapid spikes in atmospheric methane concentrations. But the UW scientists' discovery of widespread critically pressurized volumes of methane gas below continental margins may answer the often debated question of where the methane comes from and how it gets into the atmosphere so quickly.

Critically pressurized volumes of methane gas exist below many methane hydrate deposits, resulting in a potentially unstable ocean floor that is highly sensitive to changing conditions. Hornbach says any change in temperature or pressure at these critically pressured gas sites can cause hydrate to convert into methane gas. The highly pressurized gas can cause faults in the ocean floor to break apart, allowing the gas to escape.

"It's like a cork in a champagne bottle," he says. "If you shake up the champagne and build up enough pressure, the champagne bubbles can pop the cork."

Because these critically pressured gas volumes are found worldwide, Hornbach says large quantities of methane could be released during a global warming event.

"It is well documented that bottom-water temperatures in the ocean increase by approximately 5 degrees centigrade during periods of global warming," Hornbach says. "Our study indicates that perhaps as much as 2,000 gigatons (a single gigaton is one billion tons) of methane gas might escape from the ocean into the atmosphere during such warming events."

The UW scientists also contend that massive underwater landslides -- the relics of which sprawl across continental margins -- may be the direct result of ocean floor failures caused by overpressured methane gas.

Much of the project's data was collected at Blake Ridge in the Atlantic Ocean, located 300 miles off the coast of North Carolina. The scientists used soundwave technology to image beneath the ocean floor, Hornbach says, and dove some three kilometers below the surface of the Atlantic to find samples of methane gas leaks. The research was funded jointly by the U.S. National Science Foundation and the U.S Department of Energy.

[alloysteel]

There is potential to recover what may be a nearly limitless source of energy, as methane gas in quantities which dwarf all other known and anticipated sources of fossil energy on the entire planet. Best of all, this is a constantly renewing source. All we got to do is mine the ocean bottom. We have the technology, and this promises to be more economically feasible than drilling for petroleum.

[ClearCase_guy]

So, Global Warming causes Global Warming? I read this to say that warmer oceans caused by Global Warming will release the methane which then becomes the source of Global Warming. Seems somewhat circular. I need a grant to sort this out.

[DB]

So a good under sea earthquake could set things off...

And why is Mars warming?

The Sun is the only reasonable answer.

And that is probably why we are warming.

[samtheman]

New studies confirm that large methane gas clouds are released from the sites of Democratic Primary Debates.

[cinnathepoet]

a potentially unstable ocean floor that is highly sensitive to changing conditions.

One extra flush will do it!

[Dallas59]

I still think it's source is my Uncle Jerrys Homemade Chili..and Uncle Jerry.

[alloysteel]

I am not saying this is the answer to much of anything. But there is occasionaly a "burp" of gas release, when a warm stream of water hits one of these veins of methane hydrate, which is found at a depth of 1,000 feet or more. Ocean temperature at that depth is normally 4°C, or about 38°F. Water is at its most dense at that temperature, and methane hydrate is a stable amorphous solid. A flow of water that warms the temperature by only a few degrees results in the methane hydrate destablizing, and turning into a gas, escaping to the surface. This huge "burp" results in a gas-water mixture of temporarily much lower density than water alone, which may explain mysterious disappearances of ships and boats in places like the Bermuda Triangle. The warmer Gulf Stream warms up the water at greater depths, and the methane hydrate breaks down. The buoyancy of the sea is momentarily reduced, and the vessel sinks, like a rock.

[alloysteel]

Apparently this cycle of concentration of methane hydrate, and release from time to time, has been going on for eons. A number of natural gas pockets formed under layers of ooze, which later formed into shale rock strata, are the result of methane hydrate coming into contact with warming from radiant heat from the earth's interior. A gas dome is formed, and the methane remains trapped in the dome until tapped. Or until it bursts forth through a seam in the rocks.

[toomuchcoffee]

Golly, and just a few years ago there was a move to seriously reduce the number of bovines in the world because they produced so much methane. And, what about termites? Probably the worlds biggest supplier of methane gas...

[dixierat22]

Termites can't old a candle to the likes of Dean, Clark, et al

[kidd]

An article supporting oceanic outgassing.

This may cause some heartburn in the "SUVs are causing global warming" crowd.

[alnitak]

Hi alloy, do you know this site from the US Dept of Energy?

Worldwide, estimates of the natural gas potential of methane hydrates approach 400 million trillion cubic feet -- a staggering figure compared to the 5,000 trillion cubic feet that make up the world's currently known gas reserves.

That is, gay hydrates are 80,000 times more abundant that conventional gas reserves. We are not going to run out of fossil fuels - ever.

[boris]

"So, Global Warming causes Global Warming? I read this to say that warmer oceans caused by Global Warming will release the methane which then becomes the source of Global Warming. Seems somewhat circular. I need a grant to sort this out."

I'll help. The conclusion they want you to draw is that we might set off a mighty fart of methane from the sea-bottom if we keep 'warming'. Fortunately we are not causing any warming, but let that be.

Here's the crux: the heat capacity of the oceans is gigantic. To cause a 5-degree increase in the temperature of the oceans is beyond human ability--and will be for probably the next 100,000 years.

Breath easy, friend.

--Boris

[hotpotato]

All we got to do is mine the ocean bottom.

That sounds expensive. We have to go mine Mars, first.

[Mike Darancette]

So, what has been the change in sea floor water temperatures off the coast of NC in the last 15,000 years since the glaciers have retreated? But I'm sure that it is the SUVs bought by Freepers in that last 5 years that will tip the world into worldwide heating.

[alloysteel]

Not as difficult as one might think. Consider such an effort as the first step to breaking the power of various cartels in the world. We already have the methods of deep exploration, and methan hydrate seems to be in generous supply all over the ocean bottoms. A bottom dredge, easier to put down than drilling for oil or gas from a rig anchored out in the Gulf of Mexico, would pull up the crystals of methane hydrate, keeping them cold until they could be expanded in a collection unit and recompressed into liquid natural gas, from where they could be shipped all over the world. Compressed natural gas, all by itself, is a satisfactory fuel source for internal combustion engines, with far less pollution potential than even the most carefully refined gasoline or Diesel. The only reason for it not being already widely adopted is the comparative difficulty in distributing to fuel stations and fueling of vehicles, as compared to refined gasoline. Distribution is easy enough, just use the natural gas pipelines that already exist, but there is the problem of fueling. Swapping out a filled tank for an empty? High-pressure refilling of the on-vehicle tank? Cryogenic storage of the methane?

I see a LOT of potential for engineering here.

[Libertarianize the GOP]

ping

[alloysteel]

There have actually been periods of fluctuation, as the Gulf Stream has shifted flow, bring warmer water to regions where the methane hydrate has concentrated, and may have been a contributing factor during the Middle Ages, when ther was a spike in global temperatures, around 800 AD. The Norsemen traveled as far west as Greenland (which really did have some green at that time) and possibly to Newfoundland. That temperature spike may have been due to a huge methane release somewhere in the region of Iceland.

[Eva]

That was my understanding as well. It seems as though the title was created to match the agenda of global warming, blaming global warming on global warming, when what they really meant was that natural underwater events, caused by pent up pressure from the gas, is causing huge releases of methane, which causes the increase in temperature, which in turns causes more release of gas.

This study does not even take into account the fact that the oil companies have been releasing gas into the air since the inception of drilling for oil in Alaska, for lack of anything better to do with the gas. Actually I think that they may be injecting it back into the oil, now, but I am not sure. The environmentalists would do us all a big favor if they would approve the natural gas pipeline from Alaska.

[farmfriend]

Rights, farms, environment ping.

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