Climate trouble may be bubbling up in Arctic

By Charles J. Hanley

updated 11:44 a.m. ET Sept. 2, 2009

Editor's Note: This report is part of a periodic look by the Associated Press at climate issues ahead of global talks in December to work out a new emissions treaty.

MACKENZIE RIVER DELTA, Northwest Territories - Only a squawk from a sandhill crane broke the Arctic silence — and a low gurgle of bubbles, a watery whisper of trouble repeated in countless spots around the polar world.

"On a calm day, you can see 20 or more 'seeps' out across this lake," said Canadian researcher Rob Bowen, sidling his small rubber boat up beside one of them. A tossed match would have set it ablaze.

"It's essentially pure methane."

Pure methane, gas bubbling up from underwater vents, escaping into northern skies, adds to the global warming gases accumulating in the atmosphere. And pure methane escaping in the massive amounts known to be locked in the Arctic permafrost and seabed would spell a climate catastrophe.

Is such an unlocking under way?

Researchers say air temperatures here in northwest Canada, in Siberia and elsewhere in the Arctic have risen more than 4.5 F since 1970 — much faster than the global average. The summer thaw is reaching deeper into frozen soil, at a rate of 1.5 inches a year, and a further 13 F temperature rise is possible this century, says the authoritative, U.N.-sponsored Intergovernmental Panel on Climate Change (IPCC).

In 2007, air monitors detected a rise in methane concentrations in the atmosphere, apparently from far northern sources. Russian researchers in Siberia expressed alarm, warning of a potential surge in the powerful greenhouse gas, additional warming of several degrees, and unpredictable consequences for Earth's climate.

Others say massive seeps of methane might take centuries. But the Russian scenario is disturbing enough to have led six U.S. national laboratories last year to launch a joint investigation of rapid methane release. And IPCC Chairman Rajendra Pachauri in July asked his scientific network to focus on "abrupt, irreversible climate change" from thawing permafrost.

Pitching tents on the bogs
The data will come from teams like one led by Scott Dallimore, who with Bowen and others pitched tents here on the remote, boggy fringe of North America, 1,400 miles from the North Pole, to learn more about seeps in the 25,000 lakes of this vast river delta.

A "puzzle," Dallimore calls it.

INTERACTIVE Not so permafrost View a map of permafrost areas in the Arctic, as well as an interactive graphic and a video on how greenhouse gases are released by thawing permafrost.

"Many factors are poorly studied, so we're really doing frontier science here," the Geological Survey of Canada scientist said. "There is a very large storehouse of greenhouse gases within the permafrost, and if that storehouse of greenhouse gases is fluxing to the surface, that's important to know. And it's important to know if that flux will change with time."

Permafrost, tundra soil frozen year-round and covering almost one-fifth of Earth's land surface, runs anywhere from 150 to 2,000 feet deep in this region. Entombed in that freezer is carbon — plant and animal matter accumulated through millennia.

As the soil thaws, these ancient deposits finally decompose, attacked by microbes, producing carbon dioxide and — if in water — methane. Both are greenhouse gases, but methane is many times more powerful in warming the atmosphere.

Researchers led by the University of Florida's Ted Schuur last year calculated that the top 10 feet of permafrost alone contain more carbon than is currently in the atmosphere.

"It's safe to say the surface permafrost, 3 to 5 meters, is at risk of thawing in the next 100 years," Schuur said by telephone from an Alaska research site. "It can't stay intact."

Methane also is present in another form, as hydrates — ice-like formations deep underground and under the seabed in which methane molecules are trapped within crystals of frozen water. If warmed, the methane will escape.

Undersea hills caused by leaks?
Dallimore, who has long researched hydrates as energy sources, believes a breakdown of such huge undersea formations may have produced conical "hills" found offshore in the Beaufort Sea bed, some of them more than 100 feet high.

With underwater robots, he detected methane gas leaking from these seabed features, which resemble the strange hills ashore here that the Inuvialuit, or Eskimos, call "pingos." And because the coastal plain is subsiding and seas are rising from warming, more permafrost is being inundated, exposed to water warmer than the air.

The methane seeps that the Canadians were studying in the Mackenzie Delta, amid grassy islands, steel-gray lakes and summertime temperatures well above freezing, are saucer-like indentations just 30 feet or so down on the lake bed.

The ultimate source of that gas — hydrates, decomposition or older natural gas deposits — is unclear, but Dallimore's immediate goal is quantifying the known emissions and finding the unknown.

With tent-like, instrument-laden enclosures they positioned over two seeps, each several yards wide, the researchers have determined they are emitting methane at a rate of up to almost 1 cubic yard per minute.

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