The Methane Time Bomb [ this could be the biggest story of our time
mike 532 ]
http://www.truthout.org/article/the-methane-time-bomb In
the past few days, researchers believe that the sub-sea layer of
permafrost has melted away to allow methane to rise from underground
deposits formed before the last ice age. (Photo: Getty Images)
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.
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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