View source for Broken/Special:Badtitle/NS100:JamesMoore/Methane Releases From Arctic Shelf May Be Much Larger and Faster Than Anticipated

'''Thawing by climate change of subsea layer of permafrost may release stores of underlying, seabed methane.'''

[[File:Methane1 h1.jpg|thumb|300px|Methane is leaking from the East Siberian Arctic Shelf into the atmosphere at an alarming rate.]]

'''March 4, 2010'''

                                                                       
A section of the Arctic Ocean seafloor that holds  vast stores of frozen methane is showing signs of instability and  widespread venting of the powerful greenhouse gas, according to the  findings of an international research team led by University of Alaska  Fairbanks scientists Natalia Shakhova and Igor Semiletov.
The  research results, published in the March 5 edition of the journal  Science, show that the permafrost under the East Siberian Arctic Shelf,  long thought to be an impermeable barrier sealing in methane, is  perforated and is starting to leak large amounts of methane into the  atmosphere. Release of even a fraction of the methane stored in the  shelf could trigger abrupt climate warming.

"The amount of methane  currently coming out of the East Siberian Arctic Shelf is comparable to  the amount coming out of the entire world's oceans," said Shakhova, a  researcher at UAF's International Arctic Research Center. "Subsea  permafrost is losing its ability to be an impermeable cap."

Methane  is a greenhouse gas more than 30 times more potent than carbon dioxide.  It is released from previously frozen soils in two ways. When the  organic material (which contains carbon) stored in permafrost thaws, it  begins to decompose and, under anaerobic conditions, gradually releases  methane. Methane can also be stored in the seabed as methane gas or  methane hydrates and then released as subsea permafrost thaws. These  releases can be larger and more abrupt than those that result from  decomposition.

The East Siberian Arctic Shelf is a methane-rich  area that encompasses more than 2 million square kilometers of seafloor  in the Arctic Ocean. It is more than three times as large as the nearby  Siberian wetlands, which have been considered the primary Northern  Hemisphere source of atmospheric methane. Shakhova's research results  show that the East Siberian Arctic Shelf is already a significant  methane source, releasing 7 teragrams of methane yearly, which is as  much as is emitted from the rest of the ocean. A teragram is equal to  about 1.1 million tons.

"Our concern is that the subsea permafrost  has been showing signs of destabilization already," she said. "If it  further destabilizes, the methane emissions may not be teragrams, it  would be significantly larger."

Shakhova notes that the Earth's  geological record indicates that atmospheric methane concentrations have  varied between about .3 to .4 parts per million during cold periods to  .6 to .7 parts per million during warm periods. Current average methane  concentrations in the Arctic average about 1.85 parts per million, the  highest in 400,000 years, she said. Concentrations above the East  Siberian Arctic Shelf are even higher.

<blockquote style="margin-left: auto; margin-right: auto;   text-align:center; background-color: #FFFFFF; border: solid thin   #F0F1F6; width:80%;font: italic normal normal 16px/22px Georgia,   serif;">In regard to that, one just thinks of the gigantic masses of permafrost  which contain monstrous amounts of methane gas, which is released  through the thawing and melting of the permafrost and is released into  the atmosphere. Not only is the climatic catastrophe thereby furthered more than ever,  but also still many other monstrous things occur through which life on  Earth is put into question. The monstrous masses of methane gas can far exceed the great amounts of CO2 and thereby, more than ever, destroy everything. Also, as a result of all that, the oceans, their currents and their  formation of waves, are monstrously and dangerously influenced and evoke  increased numbers of monster waves, that is to say, gigantic waves,  respectively, mega waves. This occurs along with the atmosphere being influenced in terrible ways,  especially, however, its lowest layer; therefore the troposphere, in  which the weather processes take place. Thereby storms of all kinds as well as thunderstorms become more and  more powerful and destructive and they more and more closely resemble  weather processes which once prevailed on the Earth in primeval times. The weather processes and storms which are evoked by the masses of  methane gas also evoke monstrous movements of the ocean waters, whereby  warm masses of water move right down to the floor of the ocean and churn  it up. In this way the gigantic amounts of methane gas, which are stored in the  ocean floor, are released and drift upward, where they are then swirled  around in the troposphere and reach into the upper layer of the  atmosphere. The results which come about through the release of the methane gas will then be catastrophic."'''<br /> [[FIGU_Special_Bulletin_55#The_Crime_Against_All_Life|''Billy, 11th May 2010'']]
</blockquote>
 

The East Siberian Arctic  Shelf is a relative frontier in methane studies. The shelf is shallow,  50 meters (164 feet) or less in depth, which means it has been  alternately submerged or terrestrial, depending on sea levels throughout  Earth's history. During the Earth's coldest periods, it is a frozen  arctic coastal plain, and does not release methane. As the Earth warms  and sea level rises, it is inundated with seawater, which is 12-15  degrees warmer than the average air temperature.

"It was thought  that seawater kept the East Siberian Arctic Shelf permafrost frozen,"  Shakhova said. "Nobody considered this huge area."

"This study is a  testament to sustained, careful observations and to international  cooperation in research," said Henrietta Edmonds of the National Science  Foundation, which partially funded the study. "The Arctic is a  difficult place to get to and to work in, but it is important that we do  so in order to understand its role in global climate and its response  and contribution to ongoing environmental change. It is important to  understand the size of the reservoir--the amount of trapped methane that  potentially could be released--as well as the processes that have kept  it "trapped" and those that control the release. Work like this helps us  to understand and document these processes."

Earlier studies in  Siberia focused on methane escaping from thawing terrestrial permafrost.  Semiletov's work during the 1990s showed, among other things, that the  amount of methane being emitted from terrestrial sources decreased at  higher latitudes. But those studies stopped at the coast. Starting in  the fall of 2003, Shakhova, Semiletov and the rest of their team took  the studies offshore. From 2003 through 2008, they took annual research  cruises throughout the shelf and sampled seawater at various depths and  the air 10 meters above the ocean. In September 2006, they flew a  helicopter over the same area, taking air samples at up to 2,000 meters  (6,562 feet) in the atmosphere. In April 2007, they conducted a winter  expedition on the sea ice.

They found that more than 80 percent of  the deep water and more than 50 percent of surface water had methane  levels more than eight times that of normal seawater. In some areas, the  saturation levels reached more than 250 times that of background levels  in the summer and 1,400 times higher in the winter. They found  corresponding results in the air directly above the ocean surface.  Methane levels were elevated overall and the seascape was dotted with  more than 100 hotspots. This, combined with winter expedition results  that found methane gas trapped under and in the sea ice, showed the team  that the methane was not only being dissolved in the water, it was  bubbling out into the atmosphere.

These findings were further  confirmed when Shakhova and her colleagues sampled methane levels at  higher elevations. Methane levels throughout the Arctic are usually 8 to  10 percent higher than the global baseline. When they flew over the  shelf, they found methane at levels another 5 to 10 percent higher than  the already elevated Arctic levels.

The East Siberian Arctic  Shelf, in addition to holding large stores of frozen methane, is more of  a concern because it is so shallow. In deep water, methane gas oxidizes  into carbon dioxide before it reaches the surface. In the shallows of  the East Siberian Arctic Shelf, methane simply doesn't have enough time  to oxidize, which means more of it escapes into the atmosphere. That,  combined with the sheer amount of methane in the region, could add a  previously uncalculated variable to climate models.

"The release  to the atmosphere of only one percent of the methane assumed to be  stored in shallow hydrate deposits might alter the current atmospheric  burden of methane up to 3 to 4 times," Shakhova said. "The climatic  consequences of this are hard to predict."

Shakhova, Semiletov and  collaborators from 12 institutions in five countries plan to continue  their studies in the region, tracking the source of the methane  emissions and drilling into the seafloor in an effort to estimate how  much methane is stored there. 

==Source==
* http://www.nsf.gov/news/news_summ.jsp?cntn_id=116532
{{wl-publish: 2011-05-16 12:02:13 +0100 | Jamesm }}