The melting Arctic ice is causing huge quantities of methane gas to be released into the atmosphere. Concerns about climate change-inducing greenhouse gases are often centered on carbon dioxide (CO2), but methane is a greenhouse gas that is 20 to 30 times more potent than CO2. Each methane molecule is actually about 70 times more potent in terms of trapping heat than a molecule of carbon dioxide, however, methane breaks down more quickly in the atmosphere than carbon dioxide. The sub-sea layer of permafrost traps methane, preventing it from escaping, but as it melts it allows the methane to rise from underground deposits. According to scientists, large releases of methane gas can cause rapid climate changes.
There are historical precedents to back-up this assertion. Scientists believe that long ago, sudden releases of methane were responsible for rapid increases in global temperatures, dramatic changes to the climate, and even the mass extinction of species.
The Paleocene/Eocene thermal maximum (55.5 Million years ago) is a period with drastic climate change due to massive releases of methane. It has also been suggested that large temperature swings during the last glacial period have been caused by abrupt releases of methane.
Hundreds of millions of tons of methane gas are locked beneath the Arctic permafrost, which extends from the mainland into the seabed of the relatively shallow sea of the East Siberian Arctic Shelf.
Researchers at the Russian Academy of Sciences, the University of Alaska, and Stockholm University have been surveying the seabed of the East Siberian Arctic Shelf off northern Russia for nearly 20 years. Early in December, they reported dramatic and unprecedented volumes of methane being released from the Arctic seabed. They estimate that eight million tons of methane are currently leaking into the atmosphere every year. Vast amounts of methane have been seen bubbling to the surface of the Arctic Ocean. There are fields in the Arctic where the release is so intense that the methane does not have time to dissolve into the seawater but rises to the surface as large bubbles.
In an exclusive interview with the Independent, lead scientist Igor Semiletov said that he has never before witnessed the scale and force of the methane being released from beneath the Arctic seabed. Dr. Semiletov made his findings public early in December at the American Geophysical Union meeting in San Francisco.
“Earlier we found torch-like structures like this but they were only tens of
metres in diameter. This is the first time that we’ve found continuous, powerful
and impressive seeping structures, more than 1,000 metres in diameter. It’s
amazing,” Dr. Semiletov said. “I was most impressed by the sheer scale and high
density of the plumes. Over a relatively small area we found more than 100, but
over a wider area there should be thousands of them.”
Recent observations suggest that previous surveys may have significantly underestimated the amount of methane being released into the atmosphere from the Arctic seabed.
This new information was recorded in late summer 2011 by Dr. Semiletov and his team of researchers. The scientists onboard the vessel Academician Lavrentiev conducted an extensive survey of 10,000 square miles of sea off the East Siberian coast. The scientists made their observations with the help of four highly sensitive seismic and acoustic instruments that monitor the methane seeping from the ocean floor.
“In a very small area, less than 10,000 square miles, we have counted more
than 100 fountains, or torch-like structures, bubbling through the water column
and injected directly into the atmosphere from the seabed,” Dr. Semiletov said.
“We carried out checks at about 115 stationary points and discovered methane
fields of a fantastic scale – I think on a scale not seen before. Some plumes
were a kilometre or more wide and the emissions went directly into the
atmosphere.”
Expeditions in the Laptev Sea in 1994 did not detect elevated methane levels. However, since 2003 a rising number of methane “hotspots” have been detected. Research prepared for publication by the American Geophysical Union in 2008 by Dr. Orjan Gustafsson of Stockholm University in Sweden indicated that anomalies were recorded in the East Siberian Sea and the Laptev Sea. These preliminary findings were uncovered by scientists aboard the research vessel Jacob Smirnitskyi. At the time, Gustafsson was quoted as saying:
“The conventional thought has been that the permafrost ‘lid’ on the sub-sea
sediments on the Siberian shelf should cap and hold the massive reservoirs of
shallow methane deposits in place. The growing evidence for release of methane
in this inaccessible region may suggest that the permafrost lid is starting to
get perforated and thus leak methane… The permafrost now has small holes. We
have found elevated levels of methane above the water surface and even more in
the water just below. It is obvious that the source is the
seabed.”
In 2011, the scientists aboard the vessel Academician Lavrentiev revealed much higher concentrations of methane covering thousands of square miles of the Siberian continental shelf. These researchers found Arctic seabed methane up to 100 times background levels.
According to Natalia Shakhova, of the International Arctic Research Center at the University of Alaska Fairbanks, “The concentration of atmospheric methane increased three times in the past two centuries from 0.7 parts per million to 1.7ppm, and in the Arctic to 1.9ppm. That’s a huge increase, between two and three times, and this has never happened in the history of the planet.”
The Arctic is warming faster than any other region on earth. As a whole, the Arctic has experienced an average temperature increase of 4C over recent decades. The World Meteorological Organization said that northern areas like the Russian Arctic experienced the greatest increases in temperature in 2011. They also report that since 1970, the Arctic has warmed at a rate twice as fast as the rest of the globe.
Scientists predict that over the next thirty years 45 billion metric tons of carbon from methane and carbon dioxide will seep into the atmosphere as the permafrost thaws. By the end of the century, it is expected that about 300 billion metric tons of carbon will be released from the thawing Earth.
Adding in that gas means that warming would happen “20 to 30 percent faster than from fossil fuel emissions alone,” said Edward Schuur of the University of Florida. “You are significantly speeding things up by releasing this carbon.”
The release of trapped methane will cause higher temperatures, leading to even more melting of the permafrost and the release of yet more methane. This troubling trend of melting permafrost on the floor of the Arctic Ocean is accompanied by a dramatic decline in summer sea ice covering the surface. The loss of sea ice will further accelerate the warming trend because an open ocean absorbs more heat from the sun than a reflective ice surface. This represents strong positive feedback that amplifies anthropogenic warming.
Scientists have estimated the amount of methane stored beneath the Arctic to be greater than the total amount of carbon locked up in global coal reserves. Subsea permafrost is losing its ability to be an impermeable cap and models suggest that if even only one percent of the methane were released from the ocean floor, it would radically accelerate global warming.
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