Vast methane 'plumes' seen in Arctic
ocean as sea ice retreats
Dec. 13, 2011 - STEVE CONNOR - independent.co.uk
Russian research team astonished after finding 'fountains' of methane bubbling to surface
Dramatic and unprecedented plumes of methane – a
greenhouse gas 20 times more potent than carbon
dioxide – have been seen bubbling to the
surface of the Arctic Ocean by scientists undertaking
an extensive survey of the region.
The scale and volume of the methane release has
astonished the head of the Russian research team
who has been surveying the seabed of the East Siberian
Arctic Shelf off northern Russia for nearly 20 years.
In an exclusive interview with The Independent,
Igor Semiletov, of the Far Eastern branch of the
Russian Academy of Sciences, said that he has never
before witnessed the scale and force of the methane
being released from beneath the Arctic seabed.
"Earlier we found torch-like structures like
this but they were only tens of metres in diameter.
This is the first time that we've found continuous,
powerful and impressive seeping structures, more
than 1,000 metres in diameter. It's amazing," Dr
Semiletov said. "I was most impressed by the
sheer scale and high density of the plumes. Over
a relatively small area we found more than 100, but
over a wider area there should be thousands of them."
Scientists estimate that there are hundreds of millions
of tonnes of methane gas locked away beneath the
Arctic permafrost, which extends from the mainland
into the seabed of the relatively shallow sea of
the East Siberian Arctic Shelf. One of the greatest
fears is that with the disappearance of the Arctic
sea-ice in summer, and rapidly rising temperatures
across the entire region, which are already melting
the Siberian permafrost, the trapped methane could
be suddenly released into the atmosphere leading
to rapid and severe climate change.
Dr Semiletov's team published a study in 2010 estimating
that the methane emissions from this region were
about eight million tonnes a year, but the latest
expedition suggests this is a significant underestimate
of the phenomenon.
In late summer, the Russian research vessel Academician
Lavrentiev conducted an extensive survey of about
10,000 square miles of sea off the East Siberian
coast. Scientists deployed four highly sensitive
instruments, both seismic and acoustic, to monitor
the "fountains" or plumes of methane bubbles
rising to the sea surface from beneath the seabed.
"In a very small area, less than 10,000 square
miles, we have counted more than 100 fountains, or
torch-like structures, bubbling through the water
column and injected directly into the atmosphere
from the seabed," Dr Semiletov said. "We
carried out checks at about 115 stationary points
and discovered methane fields of a fantastic scale – I
think on a scale not seen before. Some plumes were
a kilometre or more wide and the emissions went directly
into the atmosphere – the concentration was
a hundred times higher than normal."
Dr Semiletov released his findings for the first
time last week at the American Geophysical Union
meeting in San Francisco.