Retreating Ice Sheets Spurred Massive Methane Expulsions from Arctic Sea Floor

Ice sheets provided perfect conditions for subglacial gas hydrate formation, but…

A new study published in Science shows that hundreds of massive, kilometer-wide craters, were formed on the Arctic ocean floor following substantial methane blowouts about 12,000 years ago.

Abstract

Widespread methane release from thawing Arctic gas hydrates is a major concern, yet the processes, sources, and fluxes involved remain unconstrained. We present geophysical data documenting a cluster of kilometer-wide craters and mounds from the Barents Sea floor associated with large-scale methane expulsion. Combined with ice sheet/gas hydrate modeling, our results indicate that during glaciation, natural gas migrated from underlying hydrocarbon reservoirs and was sequestered extensively as subglacial gas hydrates. Upon ice sheet retreat, methane from this hydrate reservoir concentrated in massive mounds before being abruptly released to form craters. We propose that these processes were likely widespread across past glaciated petroleum provinces and that they also provide an analog for the potential future destabilization of subglacial gas hydrate reservoirs beneath contemporary ice sheets.

The giant craters were formed about 12,000 years ago, but are still seeping large quantities of methane and other gases. Illustration: Andreia Plaza Faverola. Source: CAGE

The craters were formed about 12,000 years ago; however, methane is still leaking profusely from them.

“The crater area was covered by a thick ice sheet during the last ice age, much as West Antarctica is today. As climate warmed, and the ice sheet collapsed, enormous amounts of methane were abruptly released. This created massive craters that are still actively seeping methane” says Karin Andreassen, the study lead author and professor at CAGE Center for Arctic Gas Hydrate, Environment and Climate at UiT The Arctic University of Norway.

Related Links

• https://cage.uit.no/news/massive-craters-formed-methane-blow-outs-arctic-sea-floor/

FIRE-EARTH Focus: Arctic Ocean

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Breaking the Arctic Silence

[Prepared by FIRE-EARTH Science Team.]

• Presentation is available from FIRE-EARTH PULSARS.

 

Guess what, the Arctic temps are 5 ºC warmer!

Who’s Afraid of the Heating Arctic?

Arctic fall temperatures are at a record 5 ºC above normal

Fall temperatures in the Arctic are a record 5 ºC warmer than the average as less sunlight is reflected because of the major loss of sea ice  allowing  more solar heating of the ocean to occur, NOAA reported. Winter and springtime temperatures remain relatively warm over the entire Arctic, in contrast to the 20th century and consistent with an emerging global warming influence.

The Arctic-wide warming trend that began about 4 decades ago continues, with 2007 recorded as the warmest year ever for the Arctic.

Arctic-wide annual averaged surface air temperature anomalies (60°–90°N) based on land stations north of 60°N relative to the 1961–90 mean.

As more more of the ice cover was lost during the the 2005 to 2007 melt season, the ocean absorbed more heat from solar radiation which resulted in the ice freeze-up occurring later than usual.  Surface air temperature (SAT) remained high into the following autumns, with warm anomalies above an unprecedented +5 °C during October and November across the central Arctic. Report summary.

Near surface air temperature anomaly map for October and November for recent years with a reduced sea ice cover, 2005–2007. Data are from the NCEP – NCAR reanalysis through the NOAA /Earth Systems Research Laboratory, generated online CDC/NOAA.

“Changes in the Arctic show a domino effect from multiple causes more clearly than in other regions,” said James Overland, an oceanographer at NOAA’s Pacific Marine Environmental Laboratory in Seattle and one of the authors of the report, Atmosphere.

“It’s a sensitive system and often reflects changes in relatively fast and dramatic ways.”

Ice breaks away from a frozen coastline near the Norwegian Arctic town of Longyearbyen April 23, 2007, an earlier than usual spring thaw. REUTERS/Francois Lenoir (NORWAY). Image may be subject to copyright.

Hell hath no fury like a planet with little autumn ice!

Related Links:

• Climate Change Spreads “Deadly Dozen” Diseases
• Arctic Sea Ice: Likely Record-Low Volume
• Belgium buys Hungarian rights to pollute environment!
• A Haiku for Earth
• Canada’s Ice Shelves Lose Quarter of their Cover
• Arctic ice cover second-lowest on record
• 3 million acres of spruce killed in Alaska in 15 years
• Hilarious Polar Bear News!
• Oh, PLEEZE!
• Is 350 ppm Safe? Hell, NO!

See Also:

• Alaska (Index page for Alaska environmental issues, Big Oil, politics, CORRUPTION, Sarah Palin, even the moose and polar bear …)

Oh, PLEEZE!

Not the Arctic Ocean, it’s already too crowded!

China to deploy first mooring system in the Arctic

Xinhua – China will install its first annual deep-sea subsurface mooring system in the Arctic Ocean to monitor the long-term marine changes in the Arctic ocean, members of China’s third Arctic expedition said Sunday.

The system will collect data on the temperature, salinity and speed of currents at various depth in the coming year in the Arctic Ocean, thus facilitating studies of the impacts of environmental changes in Arctic Ocean on global climate, especially on China’s climate, they said.

‘A trap, as part of the system, will catch marine lives regularly for scientific research, said the members of the expedition team aboard the Xuelong ice-breaker.’ [O RLY?]

China’s ice breaker Xuelong or “Snow Dragon” is blocked by thick ice around the Antarctica during her 25th expedition to Antarctica, on November 24, 2008. An ice detection team was formed on Tuesday to search for new routes due to the thick and condensed ice that stopped the ice breaker. [Photo: Xinhua.] Image may be subject to copyright.

Isn’t that what Japan says about catching whales?

Arctic Ocean may become ice-free for part of each year, bringing devastation to Arctic inhabitants. Photo credit: Jeanne M. Bowles

Vanishing Lakes

Source: Media Relations

Researchers from the Woods Hole Oceanographic Institution (WHOI) and the University of Washington (UW) have for the first time documented the sudden and complete drainage of a lake of meltwater from the top of the Greenland ice sheet to its base.

From those observations, scientists have uncovered a plumbing system for the ice sheet, where meltwater can penetrate thick, cold ice and accelerate some of the large-scale summer movements of the ice sheet.

According to research by glaciologists Sarah Das of WHOI and Ian Joughin of UW, the lubricating effect of the meltwater can accelerate ice flow 50- to 100 percent in some of the broad, slow-moving areas of the ice sheet.

“WHOI glaciologist Sarah Das stands in front of a block of ice that was raised up 6 meters by the sudden drainage of a meltwater lake in Greenland. (Photo by Ian Joughin, UW Polar Science Center)” Image may be copyrighted. See FEWW Fair Use Notice!

“We found clear evidence that supraglacial lakes—the pools of meltwater that form on the surface in summer—can actually drive a crack through the ice sheet in a process called hydrofracture,” said Das, an assistant scientist in the WHOI Department of Geology and Geophysics. “If there is a crack or defect in the surface that is large enough, and a sufficient reservoir of water to keep that crack filled, it can create a conduit all the way down to the bed of the ice sheet.”

But the results from Das and Joughin also show that while surface melt plays a significant role in overall ice sheet dynamics, it has a more subdued influence on the fast-moving outlet glaciers (which discharge ice to the ocean) than has frequently been hypothesized. (To learn more about this result, read the corresponding news release from UW.)

The research by Das and Joughin was compiled into two complementary papers and published on April 17 in the online journal Science Express. The papers will be printed in Science magazine on May 9. Full press release Copyright ©2007 Woods Hole Oceanographic Institution, All Rights Reserved.