Arctic Ocean spewing methane, researchers say
Their article, which appeared Sunday in the peer-reviewed journal Nature Geoscience, states that the Arctic Ocean is releasing methane at a rate more than twice what scientific models had previously anticipated.
Natalia Shakhova and Igor Semiletov at UAF's International Arctic Research Center have spent more than a decade researching the Arctic's greenhouse gas emissions, along with scientists from Russia, Europe and the Lower 48.
Shakhova, the lead author of the most recent report, said the methane release rate likely is even greater than their paper describes.
"We decided to be as conservative as possible," Shakhova said. "We're actually talking the top of the iceberg."
The researchers worked along the continental shelf off the northern coast of eastern Russia -- the East Siberian Arctic Shelf, which is underlain by sub-sea permafrost.
Much like the now-submerged Beringia, the land bridge that once connected Alaska to Russia, the East Siberian Arctic Shelf was dry land until around 7,000 to 15,000 years ago, when it flooded and became part of the Arctic Ocean. During that time on dry land, the shelf developed a layer of permafrost that is now in danger of melting away and releasing vast amounts of greenhouse gases.
Past studies in Alaska and other circumpolar regions have stated that the boreal forests covering much of the world's Arctic and sub-Arctic dry land contain more than 30 percent of the world's stored carbon. This carbon is protected from atmospheric release in large part by the permafrost layer.
The submerged East Siberian Arctic Shelf contains much of the same stored carbon as the dry-land tundra just to its south, but it also contains at least 17 teragrams of methane, the study states. A teragram is equal to 1 million tons.
Those carbon stores are similarly protected by the layer of sub-sea permafrost, but that permafrost is teetering on the brink of disappearing.
Core samples taken of the sub-sea permafrost by Shakhova and her peers showed temperatures near the freezing mark, around 30 to 32 degrees. Both the top and lower layers of sediment had already thawed.
Some climate modelers had previously suggested the sub-sea permafrost would not thaw for 5,000 to 7,000 years, but according to Shakhova's team, the data gathered from the actual shelf shows the process is happening on a much more rapid timescale.
"What we're observing right now is much faster than what we anticipated and much faster than what was modeled," Shakhova said.
This revelation should be a cause for alarm, Shakhova said.
"Absolutely. We think so," she said. "We should not only just worry. We should study."
Climate scientists have constructed what they call a carbon budget to determine how much carbon-based gas, such as methane and carbon dioxide, is being released into the atmosphere. Many climate change projections are based on this budget.
The consensus carbon budget estimates that more than half of carbon emissions are human-caused, but these estimates vastly underestimate the amount of carbon stored in the Arctic shelves, Shakhova said.
"I believe strongly the Arctic sources are understated and need to be paid more attention," Shakhova said.
The UAF researchers also concluded the Arctic methane release creates a positive feedback loop. As temperatures increase, more methane is released and as more methane is released temperatures increase.
In addition, storms throughout the Arctic Ocean have increased in the past decade, according to multiple studies cited by the UAF team. These storms speed up the methane release just as shaking a soda causes the carbonation to rise more rapidly to the top and escape.
In the end, the Arctic and sub-Arctic regions may have the most to lose.
"When something is warming, when warming occurs, what, do you think, part of the globe will be affected first?" Shakhova said. "The Arctic is warming twice as fast as the rest of the globe. ... This is what affects the number of cyclones. This is what affects the sea ice, which is shrinking."
Shakhova didn't want to dwell on predictions or possible outcomes from such rising temperatures. What she wanted to see, she said, was more primary research in the Arctic itself to determine what is happening.
"Our study is not about being depressing," Shakhova said. "It's about knowledge, no matter if you like it or not."
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