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Global warming could accelerate from thawing Siberian permafrost
Posted on Saturday, June 17, 2006 @ 21:44:43 UTC by vlad
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Permafrost soil blanketing northeastern Siberia
contains about 75 times more carbon than is released by burning fossil
fuels each year. That means it could become a potent, likely
unstoppable contributor to global climate change if it continues to
thaw. So conclude three scientists in a paper set to appear Friday in
the journal Science.
“Unfortunately, it’s another large pool of
carbon on the list that could move into the atmosphere with continued
warming,” said co-author Ted Schuur, an assistant professor of ecology in the University of Florida botany department. “You start thawing the permafrost, microbes release carbon dioxide, that makes things warmer, more permafrost thaws and the process continues.”
The permafrost soil, which covers nearly 400,000 square miles
of northeast Siberia and averages 82 feet in depth, contains about 500
billion metric tons of carbon, the scientists concluded. Cars, power plants and other fossil
fuel consumers release at least 6 billion metric tons annually. If all
the Siberian permafrost thawed, decomposed and released its carbon in
the form of heat-trapping carbon dioxide, it could nearly double the
730 billion metric tons of carbon in the atmosphere presently — an
outcome that would have huge warming impact.
Scientists have long known that permafrost, short for permanently
frozen earth, contains carbon. But this latest research is the first to
examine in detail the huge swath of permafrost soil blanketing
northeast Siberia.
That soil is composed of layer upon layer of frozen windblown dust called loess. This dust fell from the air and accumulated as glaciers advanced and retreated over hundreds of thousands of years during the last ice ages
There are other similar regions around the world, including the
Midwestern United States, that have loess soils. But what sets Siberia
apart is that the dust is frozen in the permafrost, which trapped layer
upon layer of roots and other organic matter that never decomposed. The
authors showed that bacteria and fungi can eat this ancient carbon and
release it as carbon dioxide to the atmosphere as soon as the soil
thaws.
In a typical year in Siberia, plants and the surface soil thaw and
become active in the summer, then refreeze in the winter. In ancient
Siberia, as the dust accumulated, the deepest layer of previously
thawed soil remained frozen in the summer. That’s because that year’s
layer of dust effectively insulated the deepest soil.
“Every year, plants were growing new roots down into the soil, and
then the new dust fell, and some deeper roots didn’t thaw out again –
they become permanently frozen, and the process was repeated for
thousands of years as this deep loess soil accumulated,” Schuur said,
adding that preserved grass roots are readily visible in the ancient
frozen soil.
In warmer regions, the usual process is for
plants to die, decompose and return their carbon content to the
atmosphere as carbon dioxide. When spring comes, new plant growth takes
up this carbon dioxide by photosynthesis, producing oxygen. The process
repeats itself, with the amount of carbon consumed roughly proportional
to the amount of carbon produced.
Although this occurs in Siberia with the plants and surface soil,
the result of the deepest organic matter staying frozen was a huge
build-up of undecomposed, carbon-rich soil. This soil contains anywhere
from 2 to 5 percent carbon –10 to 30 times more carbon than generally
found in most deep mineral soils, according to the Science paper.
Equally significant, this soil appears to shed its carbon
relatively quickly when thawed. Schuur collected loess samples and
brought them to Florida from Siberia in their frozen state. In
laboratory tests, he found that they produced carbon dioxide at rates
roughly comparable to productive northern grassland soils as they
thawed. Using carbon dating techniques, he also confirmed that the
carbon dioxide was “old carbon” dating back tens of thousands of years.
Today, most loess remains frozen, but it is known to be thawing.
Depending on how much thaws, the result could well be a rapid release
of ancient carbon dioxide. “If these rates are sustained in the long
term, as field observations suggest, then most carbon in recently
thawed (loess) will be released within a century – a striking contrast
to the preservation of carbon for tens of thousands of years when
frozen in permafrost,” the Science paper says.
Schuur said the authors also found that thawing permafrost could
have contributed to changing atmospheric carbon dioxide concentrations
during past warming and cooling events in the earth’s history.
Source: by Aaron Hoover, University of Florida
Article from: http://www.physorg.com/news69692382.html
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Siberian thaw to speed up global warming (Score: 1)
by vlad on Saturday, September 16, 2006 @ 23:28:42 UTC
(User Info | Send a Message) http://www.zpenergy.com | Submitted by Overtone: Siberian thaw to speed up global warming
The
release of trapped greenhouse gases is pushing the world past the point of no
return on climate change
Robin McKie and Nick
Christian
Sunday September 10, 2006
Observer
The frozen bogs of
Siberia are melting, and the thaw could have devastating consequences for the
planet, scientists have discovered.
They have found that Arctic
permafrost, which is starting to melt due to global warming, is releasing five
times more methane gas than their calculations had predicted. That level of
emission is alarming because methane itself is a greenhouse gas. Increased
amounts will therefore accelerate warming, cause more melting of Siberian bogs
and Arctic wasteland, and so release even more. 'It's a slow-motion time bomb,'
said climate expert Professor Ted Schuur, of the University of
Florida.
The discovery of these levels of methane release, revealed in a
report in Nature last week, suggests that the planet is rapidly approaching a
critical tipping point at which global warming could trigger an irreversible
acceleration in climate change. 'The higher the temperature gets, the more
permafrost we melt, the more tendency it has 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.'
The news of the
danger posed by rising methane levels comes after a week in which scientists
outlined a series of disturbing developments in climate research. These
disclosures included news that nearly every wild animal in Britain has extended
its range northwards as the country heats up; ice cores from the Antarctic have
revealed that carbon dioxide levels in the atmosphere are rising at an
unprecedented rate; and analysis suggesting that the world has less than a
decade in which to halt global warming before it reaches a point of no
return.
The revelations about Siberia's methane add to these worries.
Methane is produced in soil by bacterial decomposition and normally released
into the air. However, in the permafrost regions of Siberia and the Arctic the
gas gets locked into the frozen soil, and over the millennia this has built up
to create a vast reservoir of the gas.
In addition to the methane built
up, it is also known that vast amounts of carbon dioxide are locked in the
planet's frozen zones. In total, it is estimated there could be as much as 450
billion tonnes of methane and carbon dioxide trapped in the world's
permafrost.
A team led by Katey Walter of the University of Alaska
decided to investigate the rate at which methane is being released as the world
succumbs to the effects of climate change. She chose an area along the Kolyma
river near Cherskii in Russia for the study.
The results revealed levels
of discharge that were five times higher than previous estimates. The results,
echoed by studies at 100 other sites in the north Siberia region, are alarming
because methane is far more effective at trapping heat than carbon dioxide and
is therefore potentially much more dangerous to the planet. Scientists have
calculated that methane has a global warming potential that is 23 times that of
carbon dioxide. This means that a kilogram of methane warms the planet's
atmosphere 23 times as much as the same amount of carbon dioxide.
'The
effects can be huge,' admitted Walter, adding: 'I don't think it can be easily
stopped - we would have to have major cooling. It's coming out and there is a
lot more to come out.'
Not just a wasteland
· Covering 10
million square kilometres, if Siberia were to secede from Russia it would be the
world's largest country.
· Few people live there - only three
people to every square kilometre -but it is rich in minerals, including gold and
diamonds.
· The 9,295km Trans-Siberian Railway is the world's
longest railway, running from Moscow to Vladivostok.
· The mammoth
died out in Siberia 4,000 years ago, but frozen corpses are still being dug
up.
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