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Arctic Storms, Warming Mean More Methane Released

Underneath the Arctic Ocean sits a large reserve of methane, a potent greenhouse gas. Understanding how much of that is making it to the atmosphere is an important but relatively new area of research. The latest findings published on Sunday in Nature indicate that more could be escaping than previously thought, thanks in part to stormy weather.

The East Siberian Arctic Shelf is a swath of land underneath the shallows of the East Siberian Sea, which is part of the Arctic Ocean. It stretches for 2 million square miles and contains large deposits of methane hydrates, which are frozen deposits of highly concentrated methane.

Canadian and American Coast Guard ships on a survey of the Arctic.
Credit: DVIDSHUB/Flickr

When the hydrates melt, they turn into methane gas, a greenhouse gas that is 25 times more potent than carbon dioxide. Methane hydrates are found throughout the world's oceans but generally under hundreds of feet of water. That means as they melt, there's more time for the gas to disperse and mix with the surrounding ocean water. But because the East Siberian Arctic Shelf is much shallower, with an average depth of 150 feet, there's more of a chance for that methane gas to reach the surface. That's why understanding how much methane is stored in the shelf and if those stores are stable is so important to climate researchers.

Some scientists suggested earlier this year that a massive release of methane from the shelf, referred to as a "methane bomb," could cause abrupt climate change and cost the global economy $60 trillion. That claim has been met with much skepticism, in part because the amount of methane the shelf is currently releasing and the conditions it's stored under aren’t fully understood. The remoteness, logistics and inclement weather have impeded scientists’ research access to the region until fairly recently and data has been sparse.

That, however, is beginning to change.

“In 2003, we started from zero observational data on methane available for this area,” Natalia Shakhova, an Arctic researcher at the University of Alaska and lead author of the new study, said. Her previous work built a body of evidence for how methane leaked from the seabed while her new study refines the numbers a bit more and finds that strong storms can help stir methane up the water column quickly and release it into the atmosphere.

Shakhova has spent the past decade compiling data on the East Siberia Arctic Shelf through research cruises and flyovers of the region. She published initial results in 2010, which showed that methane has been escaping at hot spots where vents have formed from a combination of geothermal heat as well as warmer river water flowing into the region. Those results showed that 7 teragrams of methane is bubbling to the surface annually. That's roughly the equivalent of 10 percent of the methane emissions from U.S. oil and natural gas production and transmission in 2012.

The new research refined those results, showing the amount of methane reaching the surface is more than double those previous estimates. In all, Shakhova and her colleagues estimate that 17 teragrams are escaping each year, though the new study says the estimates are likely on the conservative end. Shakhova said those totals are on par with emissions from the Arctic tundra.

One of the reasons for the revised estimates was more rigorous measurements using an unmanned underwater vehicle with advanced sonar technology. It provided a clearer image of the seafloor and the amount of methane escaping from vents.

Shakhova's research also shows that annual bottom water temperatures have increased 0.9°F over the past 14 years while summer temperatures have increased 1.8°F over the same period. That’s due in large part to increased runoff from rivers, which generally have warmer water than the Siberian Sea. Other research has pegged that increase at 7 percent from 1936 to 1999.

A sonar image showing the location of methane vents in a portion of the East Siberian Arctic Shelf.
Click image to enlarge. Credit: Shakhova et al., 2013

Another method Shakhova and her colleagues used to update their estimates involved taking methane measurements before and after storms passed over the shelf. The Siberian Sea has up to 70 stormy days annually when winds can help churn deeper water toward the surface.

Shakhova measured the amount of methane before and after storms in both the water column and atmosphere. After storms, methane was greatly reduced in the water column, indicating storms were helping ventilate methane into the atmosphere more rapidly.

“We should have much more concerns regarding subsea permafrost than we previously had,” Shakhova said about her results. 

At the same time, she downplayed tying the research to the methane bomb theory espoused earlier this year, saying there’s not enough evidence to make that connection.

David Archer, a carbon cycle expert at the University of Chicago agreed. “In order to ignite an Arctic methane bomb you would have to ramp up (emissions) by a factor of 10 or 100 very quickly, and there's no evidence or any proposed mechanism that could make it blow up that quickly,” he said in an email. Archer also said that while the new research shows more methane is being emitted from the area than previously thought, it still represents only about 3 percent of global methane emissions from natural and human sources.

Related Content
Greenland Mega Canyon Sends Water to the Sea
Accelerated Warming Driving Arctic into New, Volatile State
In Rapidly Changing Arctic, U.S. Playing Game of Catch-Up
Melting Permafrost Will Boost Temps, But Not Quickly 
Greenland Ice Melt Near Critical ‘Tipping Point’ 
Arctic Warming is Altering Weather Patterns, Study Shows 
 

Comments

By john harkness
on November 24th, 2013

Thanks for covering this important development. Note that the abstract says that they found what had been the permafrost at the surface of the seabed had been “entirely melted.” That permafrost cap that had been holding methane down in the areas they studied, it is gone, and the methane below is flowing quite freely out.

Reply to this comment

By Stephen Salter (Edinburgh, Scotland , EH9 3JL)
on November 25th, 2013

The “25 times more potent” figure for the ratio of warming relative to CO2 is based on integrating over 100 years.  Because of the short half life the immediate effect is much more.  In the first year after release it could be ten times greater.

Reply to this comment

By William Hughes-Games (Waipara New Zealand)
on January 22nd, 2014

A recent figure in the NSIDC web site suggested that the immediate green house potency of methane is 86 times as much as Carbon dioxide.  As you say, the 20 or 30 times figure is only true if methane is being released at the same rate from year to year since it disappears much faster than Carbon dioxide.  The present 1.8ppm atmospheric methane, if you use the X86 figure has the same effect as 155ppm Carbon dioxide.  Something strange is the recent flat lining of atmospheric methane.  Is there a sink somewhere there that we are not aware of.

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By Trucker Mark (Broomfield)
on November 25th, 2013

This is a really big problem and could lead to a phenomenon known as abrupt climate warming.

Just in September the IPCC raised to level of climate damage that methane releases can do from 25 times as bad as carbon dioxide to 86 times as bad.

http://arctic-news.blogspot.com/2013/10/abrupt-climate-change.html

How many of us know just how warm that it was in the Arctic this past summer?  In both Anchorage and Fairbanks it was the warmest summer on record, by far.

Fairbanks had 36 days of over 80 degrees including 5 days of over 90 degrees this past summer, as opposed to a normal of only 11 days per summer.

October, 2013 then saw 14 new record daily high temperatures in Fairbanks, half of them by more than 25 degrees above normal too. 

Both permafrost and shallow depth methyl hydrates melted in record amounts this past summer and continued melting well into the fall, releasing huge amounts of methane into the Arctic atmosphere.

For instance, the high temperature in Fairbanks was 53 degrees on October 28th, and to the southeast of town the high reached 62 degrees, as opposed to a normal of 19 degrees.

This link contains scientific information on the record amount of Arctic methane released even that late in the fall. 

http://arctic-news.blogspot.com/2013/11/locating-sources-of-worlds-highest-methane-levels.html

Just so that we are all aware, it will take about 6 months for the released methane to fully circulate through the atmosphere, so next spring and summer could be a lot warmer than normal too.

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By Dave (Basking Ridge, NJ 07920)
on November 25th, 2013

Shakhova - 17 Tg methane each year from the Arctic ocean seabed; “on par with emissions from the Arctic tundra.” thus making the current total Arctic methane emissions 34 Tg pa “likely on the conservative end”.

Over 100 years the global warming potential of 1 Tg methane is reported to be equivalent to about 25 Tg of CO2. 34 Tg of Arctic methane pa is therefore equivalent to about 0.85 GtCO2 pa.

Although this is clearly not - at least yet - the “methane bomb”, this is nevertheless no small amount.
For comparison the fossil fuel cap for 2C of GW is equivalent to total emissions remaining, over however long it takes to burn the fuels, of about 1000 GtCO2.

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By john harkness
on November 25th, 2013

Neven is now covering the seabed methane article on his Arctic Sea Ice blog: http://neven1.typepad.com/blog/2013/11/and-the-wind-cries-methane.html#more

Reply to this comment

By John B Davies (London UK WC1H 8BD)
on November 26th, 2013

I would like to know when the annual Methane emissions were 17 terragram per annum, was it in 2012 or 2013. this makes a huge difference in the rate of increase in emissions of Methane from Methane Hydrates.

Reply to this comment

By Brian Kahn
on November 26th, 2013

John Davies,

The 17 Tg number is based on storm data collected in 2009 and 2010, a sediment core obtained in 2011, and observations over the past 14 years so it’s not tied to one year. The paper doesn’t get into rates of change for this particular area.

Reply to this comment

By lifeisnotanerror (UK)
on November 28th, 2013

Ermm, Sam’s latest entry is even more worrying.

http://arctic-news.blogspot.co.uk/2013/11/arctic-methane-impact.html

Reply to this comment

By john harkness
on November 28th, 2013

A senior colleague of Shakhova, Semiletov, has been studying the area since the early 1990’s and reports no significant methane emissions observed from this area before about 2003. It would be good to know exactly what the rate of increase might be, though.

If storm waves have a significant effect, as the study suggests, one has to assume that there has been a big increase since sea ice extent at the end of the summer plunged over the last ten years or so. The dramatic warming and loss of spring snow cover in Siberia has also been a dramatic change over the same period that has had a significant warming effect on the waters flowing out of Siberian rivers into this area.

These are forces that are sure to accelerate over the coming years and decades, so we can certainly expect increased rates of methane release. But how fast the acceleration proceeds (if it even undergoes anything as ‘smooth’ as exponential increase, rather than the kind of catastrophic sudden release Shakhova describes), is hard to know.

So we are left to speculate. The 17 Tg figure is presented as conservative, so let’s round up to 20 Tg.

If amounts of methane coming out of the area in 2003 were a small fraction of a percentage of current amounts, say .02 Tg (though, this is just a randomly smallish number I randomly pulled out of my youknowwhat), then it would take a doubling every year to get to about current levels (unless my maths are wrong).

I’ll leave it to others to figure out where that rate of doubling would put us in ten years.

(Keep in mind that current annual emissions of CO2 from all anthropogenic sources is about 36 billion tonnes, a thousand Tg = one billion tonnes, and the short term global warming potential of methane is about 100 times that of CO2.)

Reply to this comment

By Bryan Bates (Burlington Ontario Canada L7M 1N4)
on December 2nd, 2013

You must that carbon is a metal and holds lots of power, when release it causes the worlds climate to change for the worst. When will people realize that carbon holds the power of the world. Carbon can change the batteries of today. If I had my way everything would run off carbon filled batteries. If one carbon battery hold up words of unlimited volts and hold up words of unlimited amps the would hold enough power for homes. It will happen with your support and thanks.

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