Twice as Much Methane Escaping Arctic Seafloor

The Arctic methane time bomb is bigger than scientists once thought and primed to blow, according to a study published today (Nov. 24) in the journal Nature Geoscience.

About 17 teragrams of methane, a potent greenhouse gas, escapes each year from a broad, shallow underwater platform called the East Siberian Arctic Shelf, said Natalia Shakova, lead study author and a biogeochemist at the University of Alaska, Fairbanks. A teragram is equal to about 1.1 million tons; the world emits about 500 million tons of methane every year from manmade and natural sources. The new measurement more than doubles the team's earlier estimate of Siberian methane release, published in 2010 in the journal Science.

"We believe that release of methane from the Arctic, in particular, from the East Siberian Arctic Shelf, could impact the entire globe, not just the Arctic alone," Shakova told LiveScience. "The picture that we are trying to understand is what is the actual contribution of the to the global methane budget and how it will change over time."

Waiting to escape Arctic permafrost is an area of intense research focus because of its climate threat. The frozen ground holds enormous stores of methane because the ice traps methane rising from inside the Earth, as well as gas made by microbes living in the soil. Scientists worry that the warming Arctic could lead to rapidly melting permafrost, releasing all that stored methane and creating a global warming feedback loop as the methane in the atmosphere traps heat and melts even more permafrost.

Researchers are trying to gauge this risk by accurately measuring stores of methane in permafrost on land and in the ocean, and predicting how fast it will thaw as the planet warms. Though methane gas quickly decays once it escapes into the atmosphere, lasting only about 10 years, it is 30 times more efficient than carbon dioxide at trapping heat (the greenhouse effect).

Shakova and colleague Igor Semiletov of the Russian Academy of Sciences first discovered methane bubbling up from the shallow seafloor a decade ago in Russia's Laptev Sea. Methane is trapped there in ground frozen during past ice ages, when sea level was much lower.

Shallow waters In their latest study, Shakova and her colleagues reported thousands of measurements of methane bubbles taken in summer and winter, between 2003 and 2012.

But the team also sampled seawater temperature and drilled into the ocean bottom, to see if the sediments are still frozen. Most of the survey was in water less than 100 feet (30 meters deep).

The shallow water is one reason so much methane escapes the Siberian shelf - in the deeper ocean, as methane-eating microbes digest the gas before it reaches the surface, Shakova said. But in the Laptev Sea, "it takes the bubbles only seconds, or at least a couple of minutes, to escape from the water column," Shakova said.

Arctic storms that churn the sea also speed up the release of methane from ocean water, like stirring a soft-drink releases gas bubbles, Shakova said. During the surveys, the amount of methane in the ocean and atmosphere dropped after two big Arctic storms passed through in 2009 and 2010, the researchers reported.

The temperature measurements revealed the water just above the ocean bottom warms by more than 12 degrees Fahrenheit (7 degrees Celsius) in some spots during the summer, the researchers found. And the drill core revealed that the surface sediment layers were unfrozen at the drill site, near the Lena River delta.

"We have now proved that the current state of subsea permafrost is incomparably closer to the thaw point than that of terrestrial permafrost," Shakova said.

Shakova and her colleagues attribute the warming of the permafrost to long-term changes initiated when sea levels rose starting at the end of the last glacial period. The seawater is several degrees warmer than the frozen ground, and is slowly melting the ice over thousands of years, they think.

Massive burst But other researchers think the permafrost warming started only recently. "This is the first time in 12,000 years the Arctic Ocean has warmed up 7 degrees in the summer, and that's entirely new because the sea ice hasn't been there to hold the temperatures down," said Peter Wadhams, head of the Polar Ocean Physics Group at the University of Cambridge in the U.K., who was not involved in the study. The summer ice melt season has lasted longer since 2005, giving the sun more time to warm the ocean. [10 Things You Need to Know About Arctic Sea Ice]

"If we do have a methane burst it's going to be catastrophic," Wadhams said. Earlier this year, Wadhams and colleagues in Britain calculated that a mega-methane release from the Siberian shelf could push global temperatures up by 1 degree Fahrenheit (0.6 degrees Celsius). The suggestion, published in the journal Nature, was widely debated by climate researchers. Climate change experts and international negotiators have said that keeping the rise in Earth's average temperature below 2 degrees Celsius (3.6 degrees Fahrenheit) is necessary to avoid catastrophic climate change.

Shakova said much more research is needed to understand the factors that control how much methane is released from the entire East Siberian Arctic Shelf, which covers 772,000 square miles (2 million square kilometers), or nearly one-fifth the size of the United States.

"Ten years ago we started from zero knowledge in this area," Shakova said. "This is the largest shelf in the world's oceans. That's why it's very challenging to understand the natural processes behind the methane emissions in this area."

Original article on LiveScience.

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The sea surface above the East Siberian Arctic Shelf is full of ice and bubbles.

Sept. 17, 2012

French photographer Samuel Blanc has been leading tours to Svalbard, Norway's archipelago in the Arctic, since 2007. This year the reduced sea ice extent allowed his expedition aboard the 12-passenger Polaris to circumnavigate the northern islands in early July rather than mid-August. Climate change is having a direct impact on the unique ecosystem isolated on these islands more than 400 miles north of Europe. In the following photos, Blanc gives us a tour of life on the archipelago's largest island, Spitsbergen. You can see more of his work at www.sblanc.com.

Little Auks

In west Spitsbergen, Little Auks, such as those pictured here, and other birds aren't safe on the cliffs. Hungry polar bears have learned to climb the steep gradients in search of food.

Polar Bears and Bleeding Glaciers

The dissolved iron seen in this glacier may help fight climate change. As the iron washes into the northern seas, it can help fertilize phytoplankton blooms that draw carbon dioxide out of the atmosphere.

Tundra

As global warming melts permafrost in the arctic, more carbon is released into the atmosphere. Meanwhile areas of tundra are also seeing a rise in fires.

Svalbard Reindeer

Walruses

The vast stretch of open water due to thinning of the Arctic sea ice is forcing walruses to often crowd together on beaches.

Bearded Seal

This bearded seal has found a safe spot away from polar bears and sharks. Many seals however also snooze in the water, where they are at risk of becoming of meal for the Greenland shark, the world's slowest shark.

Arctic Fox

Only three percent of the total population of arctic fox are called "Blue fox" and unlike the rest of the population, these blue critters don't turn white in the winter.

Arctic Foxes

These foxes are showing their summer colors.

Ivory Gull

Sabine Gull

Svalbard Poppy

Spitsbergen, Svalbard