Scientists Find New Global Warming 'Time Bomb'
Methane Bubbling Up From Permafrost
by Seth Borenstein for The Associated Press
Global warming gases trapped in the soil are bubbling out of the
thawing permafrost in amounts far higher than previously thought
and may trigger what researchers warn is a climate time bomb.
Methane a greenhouse gas 23 times more powerful than carbon dioxide
is being released from the permafrost at a rate five times faster
than thought, according to a study being published Thursday in the
journal Nature. The findings are based on new, more accurate measuring
techniques.
"The effects can be huge," said lead author Katey Walter
of the University of Alaska at Fairbanks said. "It's coming
out a lot and there's a lot more to come out."
Scientists worry about a global warming vicious cycle that was not
part of their already gloomy climate forecast: Warming already under
way thaws permafrost, soil that has been continuously frozen for
thousands of years. Thawed permafrost releases methane and carbon
dioxide. Those gases reach the atmosphere and help trap heat on
Earth in the greenhouse effect. The trapped heat thaws more permafrost
and so on.
"The higher the temperature gets, the more permafrost we melt,
the more tendency it is to become a more vicious cycle," said
Chris Field, director of global ecology at the Carnegie Institution
of Washington, who was not part of the study. "That's the thing
that is scary about this whole thing. There are lots of mechanisms
that tend to be self-perpetuating and relatively few that tend to
shut it off."
Some scientists say this vicious cycle is already under way, but
others disagree.
Most of the methane-releasing permafrost is in Siberia. Another
study earlier this summer in the journal Science found that the
amount of carbon trapped in this type of permafrost called yedoma
is much more prevalent than originally thought and may be 100 times
the amount of carbon released into the air each year by the burning
of fossil fuels.
It won't all come out at once or even over several decades, but
if temperatures increase, then the methane and carbon dioxide will
escape the soil, scientists say.
The permafrost issue has caused a quiet buzz of concern among climate
scientists and geologists. Specialists in Arctic climate are coming
up with research plans to study the permafrost effect, which is
not well understood or observed, said Robert Corell, chairman of
the Arctic Climate Impact Assessment, a study group of 300 scientists.
"It's kind of like a slow-motion time bomb," said Ted
Schuur, a professor of ecosystem ecology at the University of Florida
and co-author of the study in Science.
Most of the yedoma is in little-studied areas of northern and eastern
Siberia. What makes that permafrost special is that much of it lies
under lakes; the carbon below gets released as methane. Carbon beneath
dry permafrost is released as carbon dioxide.
Using special underwater bubble traps, Walter and her colleagues
found giant hot spots of bubbling methane that were never measured
before because they were hard to reach.
"I don't think it can be easily stopped; we'd really have to
have major cooling for it to stop," Walter said.|
Scientists aren't quite sure whether methane or carbon dioxide is
worse. Methane is far more powerful in trapping heat, but only lasts
about a decade before it dissipates into carbon dioxide and other
chemicals. Carbon dioxide traps heat for about a century.
"The bottom line is it's better if it stays frozen in the ground,"
Schuur said. "But we're getting to the point where it's going
more and more into the atmosphere."
Vladimir Romanovsky, geophysics professor at the University of Alaska
at Fairbanks, said he thinks the big methane or carbon dioxide release
hasn't started yet, but it's coming. In Alaska and Canada which
have far less permafrost than Siberia it's closer to happening,
he said. Already, the Alaskan permafrost is reaching the thawing
point in many areas.On the Net:
Nature: www.nature.com/nature
Warming
worry: Potent gas bubbling up faster
by Katy Walters for the Associated Press on MSNB
Methane, a gas
20 times more potent than carbon dioxide in trapping heat in the
atmosphere, appears to be bubbling up from thawing permafrost at
a rate five times faster than originally measured, scientists reported
Wednesday.
The effect, reported in this week's issue of the journal Nature,
is seen mostly in Siberia in a type of carbon-rich permafrost that
was flash frozen about 40,000 years ago. A new, more accurate measuring
technique found that methane bubbling from that permafrost under
Siberian lakes was higher than previously recorded.
“The effects can be huge,” said lead author Katey Walter
of the University of Alaska at Fairbanks. “It’s coming
out a lot and there’s a lot more to come out.”
The researchers
measured methane in two northern Siberia lakes. “We find that
thawing permafrost along lake margins accounts for most of the methane
released from the lakes, and estimate that an expansion of thaw
lakes between 1974 and 2000, which was concurrent with regional
warming, increased methane emissions in our study region by 58 percent,”
the researchers wrote.
Scientists are fretting about a global warming cycle that had not
been part of their gloomy climate forecasts: Warming already under
way thaws permafrost, soil that had been continuously frozen for
thousands of years.
Thawed permafrost releases methane and carbon dioxide. Those gases
reach the atmosphere and help trap heat on Earth in the greenhouse
effect. The trapped heat thaws more permafrost, and so on.
'A more vicious cycle'
“The higher the temperature gets, the more permafrost we melt,
the more tendency it is to become a more vicious cycle,” said
Chris Field, director of global ecology at the Carnegie Institution
of Washington. “That’s the thing that is scary about
this whole thing. There are lots of mechanisms that tend to be self-perpetuating
and relatively few that tends to shut it off.”
Siberia is dotted with lakes like these which contain methane frozen
in permafrost below the water.
Another study earlier this summer in the journal Science found that
the amount of carbon trapped in this type of permafrost —
called yedoma — is much more prevalent than originally thought
and may be 100 times the amount of carbon released into the air
each year by the burning of fossil fuels.
It won’t all come out at once or even over several decades,
but the methane and carbon dioxide will escape the soil if temperatures
increase, scientists say.
The issue of methane and carbon dioxide released from permafrost
has caused concern this summer among climate scientists and geologists.
Specialists in Arctic climate are coming up with research plans
to study the effect, which is not well understood or observed, said
Robert Corell, chairman of the Arctic Climate Impact Assessment,
a group of 300 scientists.
Slow-motion time bomb'
“It’s kind of like a slow-motion time bomb,” said
Ted Schuur, a professor of ecosystem ecology at the University of
Florida and co-author of the Science study. “There’s
these big surprises out there that we don’t even know about.”
Most of this yedoma is in north and eastern Siberia, areas that
until recently had not been studied at length by scientists.
Researcher Sergey Zimov examines a cross-section of yedoma in Siberia.
The shiny surface represents massive ice wedges. The dark sections
in between are soil and ice-age organic carbon which, when deposited
into lake bottoms, provided food for bacteria that produce methane.
What makes this permafrost special is that during a rapid onset
ice age, carbon-rich plants were trapped in the permafrost. As the
permafrost thaws, the carbon is released as methane if it’s
underwater in lakes, like much of the parts of Siberia that Walter
studied. If it’s dry, it’s released into the air as
carbon dioxide.
Scientists aren’t quite sure which is worse. Methane is far
more powerful in trapping heat, but only lasts about a decade before
it dissipates into carbon dioxide and other chemicals. Carbon dioxide
traps heat for about a century.
“The bottom line is it’s better if it stays frozen in
the ground,” Schuur said. “But we’re getting to
the point where it’s going more and more into the atmosphere.”
Vladimir Romanovsky, a geophysics professor at the University of
Alaska at Fairbanks, said he thinks the big methane or carbon dioxide
release hasn’t started yet, but it’s coming. It’s
closer in Alaska and Canada, which only has a few hundred square
miles of yedoma, he said.
In Siberia, the many lakes of melted water make matters worse because
the water, although cold, helps warm and thaw the permafrost, Walter
said.
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