stormier Arctic could fast-track the greenhouse gas into the
atmosphere, potentially accelerating global warming.
quantities of methane are escaping the East Siberian Shelf as a
result of the degradation of submarine permafrost," says Natalia
Shakhova of the University of Alaska in Fairbanks. She and her team
collected data – at a great cost – to show that vast areas are
releasing plumes of methane gas, which is escaping into the
August 2010, 11 sailors aboard a tug boat drowned in the Laptev Sea
while trying to rescue a fishing boat in the Arctic waters north of
Siberia. What didn't emerge at the time was that they were attempting
to rescue a team of Russian researchers probing whether storms that
stir up the ocean will increase the release of methane from the sea
bed as the Arctic warms.
their fishing boat, the researchers drilled into the bed of the
Laptev Sea – a hotspot of methane emissions – and used sonar to
analyse gas bubbles in the water. They found the permafrost that
usually sat beneath the sea bed was unfrozen, allowing around 500
tonnes of methane to bubble out of every square kilometre of the sea
bed each day. Bubbling seeps of methane were found along the entire
coastline of their survey area, over the East Siberian Arctic
Shelf. Similar plumes have been seen off the coast of
Svalbard in Norway.
team also measured how two storms – one in 2009 and one in 2010 –
changed the amount of methane dissolved in the water. They found that
the winds stirred up the ocean, speeding the release of gases into
have proven that the current state of subsea permafrost is
incomparably closer to the thaw point than terrestrial permafrost,
and that modern warming does contribute to warming the subsea
permafrost," says Shakhova. Increasing storminess in the Arctic,
predicted by some climate models, would speed up the release of
methane, she says.
findings, obtained as part of the International Siberian Shelf Study
Program, add weight to fears that a massive "pulse" of up
to 50 billion tonnes of methane from the Arctic could warm the world
by a degree or more. A
controversial claim earlier this year that
it could cost the global economy $60 trillion was based on earlier
findings from Shakhova's team (Nature, vol 499, p 401).
the findings don't show that a major pulse is under way. "The
total volume of methane being released is still small," said
Laurence Smith of the University of California, Los Angeles. "But
this research provides valuable new understanding of the processes of
methane bubbling during storms, conducted at great personal risk."
the second storm that the researchers monitored, the winds became so
violent that they called for help. The rescue tug sank before
reaching them. The researchers survived unharmed, and dedicate their
paper "to the memory of the crew of Russian vessel RV Alexei