[THS] !!!! Melting Methane

[Peter Webster]

http://www.truthout.org/issues_06/042308EC.shtml

Melting Methane
    By Volker Mrasek
    Der Spiegel

    Thursday 17 April 2008

    A storehouse of greenhouse gases is opening in Siberia.

    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. But can the
methane also be used as fuel?

    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.

    Russian polar scientists have strong evidence that the first stages of
melting are underway. They've studied largest shelf sea in the world, off
the coast of Siberia, where the Asian continental shelf stretches across
an underwater area six times the size of Germany, before falling off
gently into the Arctic Ocean. The scientists are presenting their data
from this remote, thinly-investigated region at the annual conference of
the European Geosciences Union this week in Vienna.

    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, currently a
guest scientist at the University of Alaska in Fairbanks who is also a
member of the Pacific Institute of Geography at the Russian Academy of
Sciences in Vladivostok.

    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, since the potent greenhouse gas develops
wherever microorganisms decompose the huge masses of organic
material from warmer eras that has been frozen here for thousands of
years.

    "A Wake-Up Call for Science"

    Data from offshore drilling in the region, studied by experts at the
Alfred Wegener Institute for Polar and Marine Research (AWI), also
suggest that the situation has grown critical. AWI's results show that
permafrost in the flat shelf is perilously close to thawing. Three to 12
kilometers from the coast, the temperature of sea sediment was -1 to
-1.5 degrees Celsius, just below freezing. Permafrost on land, though,
was as cold as -12.4 degrees Celsius. "That's a drastic difference and
the best proof of a critical thermal status of the submarine permafrost,"
said Shakhova.

    Paul Overduin, a geophysicist at AWI, agreed. "She's right," he said.
"Changes are far more likely to occur on the sea shelf than on land."

    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," said Overduin. 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," the
Canadian scientist said. 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."

    One thing is clear, though: The thawing of the Arctic sea floor will
create "new potential sources for methane ... which no one had
reckoned with until now," said Laurence Smith, a professor for
geography at the University of California in Los Angeles. Smith is
researching North Pole frost zones and expects that a thawing of the
permafrost will "supply fuel for methane engines."

    The first methane rocket thruster was tested by the US's National
Aeronautics and Space Administration (NASA) in 2007, and methane
from manure has been collected as "biogas" to heat and power homes
(more...) in experimental German towns.

    In any case, the team taking part in the Siberian study installed a
number of probes in the Laptev Sea, a central part of the broad
Siberian shelf sea. These probes are measuring the temperature on the
upper edge of the submarine permafrost. Overduin wants to pull up the
probes in August. Then, for the first time, scientists will have access to a
full year's worth of data on the conditions of the sea floor.

    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 for science."

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