By Judith Burns
Science and environment reporter, BBC News

Scientists say they have evidence that the powerful greenhouse gas methane is escaping from the Arctic sea bed.

Researchers say this could be evidence of a predicted positive feedback effect of climate change.

As temperatures rise, the sea bed grows warmer and frozen water crystals in the sediment break down, allowing methane trapped inside them to escape.
The research team found that more than 250 plumes of methane bubbles are rising from the sea bed off Norway.

Tarnocai, C., J. G. Canadell, E. A. G. Schuur, P. Kuhry, G. Mazhitova, and S. Zimov (2009), Soil organic carbon pools in the northern circumpolar permafrost region, Global Biogeochem. Cycles, 23, GB2023, doi:10.1029/2008GB003327

Substantial quantities of methane are emitted
naturally from wetlands, and this emission is
expected to change as wetlands change. Changing
rainfall patterns will cause some wetland areas to
increase in extent, others to decrease, and increases
in temperature will act to increase emissions from
wetlands. One version of the Hadley Centre climate
model includes a description of wetland methane,
and this predicts an increase in natural wetland
emissions by the end of the century equivalent to
the amount of man-made emissions projected for
that time, thus leading to a more rapid rise in
methane concentrations, and hence warming.

On the other hand, the chemical reactions in the
atmosphere which destroy methane are expected to
become more efficient in future, largely as a result
of increased water vapour. This will act as a
negative feedback on methane amounts.

Methane is also stored in permafrost, and it is likely
that some of this will be released as surface warming
extends into the permafrost and begins to melt it.

Finally, huge amounts of methane are locked up in
methane hydrates (methane clathrates) in the oceans.
They are currently at high enough pressures and
temperatures to make them very stable. However,
penetration of greenhouse effect heating into the
oceans may destabilise them and allow some of the
methane to escape into the atmosphere. The
potential for this to happen is very poorly understood.
There is concern that this may be another positive
feedback not yet included in models, although there
is little evidence for this from the behaviour of
methane during the large temperature swings
between ice ages and interglacials, and in particular
over the last 50,000 years.

Climate change and the greenhouse effect
A briefing from the Hadley Centre
December 2005

British scientists find more evidence of climate threat

By Steve Connor, Science Editor
Thursday, 25 September 2008

British scientists have discovered hundreds more methane “plumes” bubbling up from the Arctic seabed, in an area to the west of the Norwegian island of Svalbard. It is the second time in a week that scientists have reported methane emissions from the Arctic.

Methane is 20 times more potent than carbon dioxide as a greenhouse gas and the latest findings from two separate teams of scientists suggest it is being released in significant amounts from within the Arctic Circle.

By Ross Gelbspan on Science

The first evidence that millions of tons of a greenhouse gas 20 times more potent than carbon dioxide is being released into the atmosphere from beneath the Arctic seabed has been discovered by scientists.

Underground stores of methane are important because scientists believe their sudden release has in the past been responsible for rapid increases in global temperatures, dramatic changes to the climate, and even the mass extinction of species. In the past few days, researchers have seen areas of sea foaming with gas bubbling up through “methane chimneys” rising from the sea floor.

By HENRY FOUNTAIN
Published: September 18, 2008

One of the potential consequences of a warmer world, according to scientists who study such things, is the deep thawing of the permafrost. Thawing could release huge quantities of carbon into the atmosphere, as vegetation, bones and other organic material, long locked up in the deep freezer that is the permafrost, decompose.

But a study published in Science suggests that the impact of warming on the permafrost may not be as bad as forecast. The evidence comes in the form of a wedge of ancient ice found at an old mining site in the Yukon in Canada.

THE blanket of permafrost covering a fifth of the world’s land mass traps twice as much greenhouse gas as previously thought — and is therefore much more likely to trigger rapid climate change as it melts, research says.

A paper published in the journal Bioscience estimates that more than 1500 billion tonnes of carbon dioxide and methane is locked in frozen vegetation at high latitudes. This is more than double the amount of greenhouse gas now in the atmosphere.

CSIRO atmospheric scientist Pep Canadell — part of an international team of 19 scientists that worked on the paper — said while it was not possible to accurately predict how much carbon would escape from the permafrost as it warmed, the release of even a fraction would accelerate climate change dramatically.

Vladimir E. Romanovsky
Associate Professor
Geophysical Institute UAF
Fairbanks, AK

“If recent trends continue, it will take several centuries to millennia for permafrost to disappear completely in the areas where it is now actively warming and thawing. However, negative consequences of this degradation will be pronounced from the very beginning because the highest ice content in permafrost usually is found in the upper few tens of meters…

At that moment, many processes (some of them very destructive) will be triggered or intensified. The most significant impacts on ecosystems, infrastructure, carbon cycle and hydrology will be observed in areas where permafrost contains a considerable amount of ground ice in the upper few meters. Even in the polar areas, where permafrost will still be stable, the depth of the seasonal active layer will increase significantly if present trends continue…

[T]he majority of northern ecosystems are apparently carbon sinks at present time. Climate warming and drying caused by this warming permafrost degradation will change this situation. A thicker, warmer and dryer active layer will be much friendlier for microbial activities during the summer. Significantly later freeze-up of this layer in winter and warmer winter temperatures (that means much more unfrozen water in it) will considerably enhance the microbial activities during the winter. So, the arctic and sub-arctic ecosystems could turn into a source of CO2 (especially on an annual basis) very soon. Further permafrost degradation and formation of taliks will amplify these changes because a layer that will not freeze during the entire winter (talik) will appear above the permafrost, where microbial activities will not cease during the winter. In the area of “wet thermokarst” formation, new and significant sources of CH4 will be developing…

The permafrost won’t be perma for long
More carbon in the Arctic than previously thought

Slip of the tundra
CO2 released from disappearing permafrost must be factored into climate projection

Permafrost melting, methane coming, humanity doomed: more

Impermafrost
Sobering dispatches from Alaska

Are scientists overestimating — or underestimating — climate change? Part III
On the climate change ‘point of no return’

The Peat Is Gone
Siberia’s fast thaw alarms scientists

Guess It’s Not So Perma After All
Melting Siberian permafrost could release billions of tons of CO2

The bad news from Siberia continues
Thawing permafrost, oh my.

Feedback frenzy
2006, the year global warming came into focus

—

Nicholas Stern, the British economist known for a major report in which he declared that combating climate change would cost less than ignoring it, has announced that he was wrong — about how bad the problem is. “We badly underestimated the degree of damages and the risks of climate change” in the Oct. 2006 report, he said in a speech Wednesday. “All of the links in the chain are on average worse than we thought a couple of years ago.” Thawing permafrost is releasing methane, oceans are acidifying faster than expected, and carbon sinks are becoming less effective, said Stern.