Arctic Atmospheric Methane Trends 2013

It's been a while since we've looked at methane trends in the Arctic atmosphere (just a little under a year in fact).  This important greenhouse gas has been on the rise over the past several decades, though that rise has not been nearly as steady as CO2. What's worrisome to those who follow methane is the return to higher growth rates of the gas over the past few years.  This chart shows the atmospheric measurement of methane at Point Barrow cover the last 2.5 years:

What I've highlighted here in red are a few interesting features of the methane levels that are worth mentioning.

First, the horizontal red bar shows the lowest boundary of the yearly methane measured a few weeks ago. Methane always hits a low annual concentration at Point Barrow around the middle of the year, usually in June as part the natural fluctuations.  This year we saw the highest low point ever recorded.  This is significant because it shows the underlying long-term growth rate.  If you compare this year's low point to last year's, you get a sense of the upward turn in the atmospheric methane concentrations.

At the top of this graphic in the large red circle are several "anomalous" readings that were recorded over Barrow last year just about the time that GAC-2012 was hitting.  These are huge outliers, but because there were several of them occurring all about the same time, we can also assume they were valid data in the sense that it was really being recorded properly.  In direct email discussions with staff at Barrow station at the time, they characterized these as "likely" local anthropogenic sources, i.e. outgassing from drilling rigs, etc.  Note the word "likely".  These samples are sent back to a lab for analysis that can better describe the sources.  My hunch, and again, this is only a hunch, is that GAC-2012 or simply the very low ice levels of last summer or some combination, may have brought up more methane and caused these very high anomalous readings. It is also important to note that all the data points in the graph that are orange have yet to be fully validated-- though they are in the vast majority of cases.

Finally, in the small red circle is one the latest readings from Barrow.  It continues to show the higher long-term upward trend is accelerating and also shows the remainder of 2013 should be interesting to watch, as it will likely show the strong growth rate of methane in the Arctic atmosphere. Though the level will oscillate up and down a bit between now and its annual peak in early 2014, we should monitor the rest of the summer Arctic melt season for the kinds of "anomalies" that we saw last year. I will especially look for a period of anomalously high levels should another large cyclone hit in August or even September when sea ice is at its lowest. 

The bottom line of all this is that methane levels remain an important metric to gauge both current and potential future changes in the Arctic climate, and the trends should be of great concern.

---

Addendum by Neven:

Thanks go out to R. Gates for his update on methane. I'm taking the opportunity to draw attention to this effort to get methane levels back to 1250 ppb, much like the 350 movement is doing for CO2: 1250now.org

There is also a very cool interactive website that allows one to track methane in the atmosphere everywhere on the planet: Methane Tracker. The site is still in the pre-alpha phase, but when it's finished, it'll be announced here in a separate blog post.

Comments

[dorlomin]

These sort of readings are quite common and once or twice a year one of them will cause a stir. I spotted one in about December of 2010 and sent an email off to the staff at the Zeppelin Station that the readings came from, they were kind enough to reply back telling me it was a instrument error.

I'd be very very cautious over this issue as there is a great deal of hype and our friends on the other side of the mirror are always sniffing for a slip up.

[R. Gates]

dorlomin, you make a good point. It is easy to get the label of "alarmist" by looking at methane levels, especially when focusing on outlier events. My point wasn't as much about the outliers, as about the record high low point and the indication of the overall long-term trend definitely taking a turn upward. It is interesting to note the outliers, especially if they begin to happen more frequently, especially during events like GAC-2012. But, just as with CO2, ocean heat content, tropospheric temperatures, sea ice, glaciers, and all the other metrics we use to measure the long-term direction of the climate, taking note of the trend and benchmarks (like a jump up in the season low point for methane concentration) is worth watching and noting, IMO.

[Apocalypse4Real]

Dorlomin,

I appreciate your concerns with the ground station readings, and at times Barrow and elsewhere have had errors or local sources.

We now have a new tool that is going to dramatically change how we are able to monitor CH4 - from a few data points, to a global 3-D perspective.

R Gates,

On the other hand, some of the ppb readings are definitely not errors or anomalies. I have followed the METOP 2 IASI CH4 imagery from the OSPO since December, 2012. I have posted a lot of that imagery through this website:

https://sites.google.com/site/apocalypse4real/home/2011-airs-ch4-359-hpa-vs-iasi-ch4-970-600-mb

My frustration was that I could only show 2 or three layers of methane at any time - not the whole 3-D spectrum globally. I posted some layers as displays using Google Earth to help us see how CH4 was distributed in the Arctic, but not globally, until I saw how much methane has concentrated in the Antarctic.

Through this year I have learned a lot about methane release, in atmospheric layers and locations that I did not expect - like the Sahara Desert!

Fortunately, someone with the passion for the issue of methane release and with the technical skills to take every layer of METOP 2 IASI output and display it in 3-D over time has taken up this project.

The new website is http://methanetracker.org

methanetracker.org makes it possible to track methane release above 1950 ppb at any hPa/mb that it occurs during - as short as a 12 hour period - to as long as YTD, 2013.

NOTE: methanetracker.org only works in Google Chrome.

There are two videos that Omar Cabrera, the developer, has made that provide insight into how powerful methanetracker is, and some of the things he and I have discovered as we discussed and worked through this project.

You will want to watch these videos (in consecutive order) first before using the website. The videos are introductory, and reveal some things we have observed from the imagery.

The You Tube links are:

Video 1: http://www.youtube.com/watch?v=E1OluDXNXJ4

Video 2: http://www.youtube.com/watch?v=j_xaifA5-wI

methanetracker.org is still a work in progress and is not fully documented or debugged. One reason we are not finished is that we want methanetracker.org to be able to model the entire ppb range. To do so requires it to migrate to VAPOR, a fully 3-D software product in the next few weeks.

We hope you will sign up, explore, discover and comment about the unseen spread of CH4 in our atmosphere at high levels.

Here is an example of the power of methanetracker.

From the using the individual (micro) layer mode, I observe that on July 9, 2013, from 0-12 hr Z, in the East Siberian Sea, between 71-76N and 154-160E there were numerous concentrations of methane above 1950 ppb between 918 mb (2,700 ft) to 650 mb (11,775 ft).

By adding the near real time sea ice layer, I can observe that the ice is melting and breaking up in the same area, likely having an impact on the release.

At the macro level, I can observe, that in February to April,2013 there was a massive release of methane with concentrations above 1950 ppbv that covered the Norwegian, Greenland, Barents and Kara seas, an area larger that the continental United States.

So we hope you'll watch the videos and start exploring near-real time 3-D methane release based upon some of the best satellite imaging available today.

As you will see, we are incredibly indebted to Omar for what he has created.

methanetracker.org has the potential for revolutionizing how we visualize the sources, movement, and impacts of global methane release - and more.

If its OK with Neven, we will explain more in a blog post.

Also, I have started a methanetracker.org thread on the Forum.

A4R

[Neven]

If its OK with Neven, we will explain more in a blog post.

This speaks for itself. I've added the link to Methane Tracker at the end of this blog post. Send me a text as soon as Omar has the site completely ready (it already looks great BTW) and I'll post it.

[Rob Dekker]

R Gates, thanks for your interesting post.

I have a question about the 'sort of' annual cycle. It seems from the NOAA graph that in winter methane concentrations at Barrow are higher than in summer, and specifically are highest in December and lowest in June.

What could be the cause of that ?
Are we maybe measuring methane leaks from heater systems in Barrow homes ?

[dorlomin]

"as about the record high low point and the indication of the overall long-term trend definitely taking a turn upward."

The long term trend is clearly upwards. Just their are some rather dodgy characters on the fringes of these debates who have used such spot anomalies to proclaim massive, civilisation destroying, volumes of methane are being released.

And if they get a bit of publicity it will be used as a club against us all by the other side of the mirror.

[dorlomin]

"At the macro level, I can observe, that in February to April,2013 there was a massive release of methane with concentrations above 1950 ppbv that covered the Norwegian, Greenland, Barents and Kara seas, an area larger that the continental United States."

How unusual is this? How many years of this tool do we have to look at.

This is an area that has long been of concern, for as long as I have been following the science.

[dorlomin]

" It seems from the NOAA graph that in winter methane concentrations at Barrow are higher than in summer, and specifically are highest in December and lowest in June."

http://www.newscientist.com/article/mg20026855.000-arctic-tundra-releases-annual-methane-burp.html

Some people believed that as the ground froze, it was forcing out methane that had been accumulated.

Perhaps other newer theories now exist.

[Climate Changes]

Good post R. Gates.

"It seems from the NOAA graph that in winter methane concentrations at Barrow are higher than in summer, and specifically are highest in December and lowest in June.
What could be the cause of that ?"

After gassing out from the Arctic ocean selves and permafrost, CH4 accumulates in the atmosphere during the polar night but as the Sun returns to the Arctic, UV + Hydroxil Radical convert atmospheric CH4 into CO2, H2O. See here: http://en.wikipedia.org/wiki/Hydroxyl_radical
The resulting H2O, after nucleation with cosmic dust, forms Noctilucent Clouds (NLC's) which are increasing in intensity and extent as more CH4 gasses out every year. Given the record amounts of CH4 seen last Winter I was able to predict with ease that NLC season would be pretty good... and proof's in the pudding :). http://spaceweather.com/gallery/index.php?title=nocti&title2=NLC

So to resume, CH4 decreases from Spring to Summer because it gets destroyed and converted to other gases. However, as more CH4 scapes (and there's no going back) more spectacular NLC displays are to be expected.

[Climate Changes]

where did my post go? :(

[It was in the spam bucket, sorry about that; N.]

[Martin Gisser]

Rob Dekker, the annual cycle is due to reactions with hydroxyl radicals, which is the dominant methane sink: The hydroxyl radical is produced in the atmosphere by sunlight, which explains the cycle. Hydroxyl eats methane in a complicated network of reactions ending in CO2 and H2O.

http://en.wikipedia.org/wiki/Atmospheric_methane#Removal_processes

[Clare]

Sorry OT
Are you following this Greenpeace demo of 6 women climbing the Shard (of ice) in London?
http://iceclimb.savethearctic.org/

[Werther]

Yes I do, Clare.
BTW I'm appalled by the hypocrite Shell-reaction "they (Shell; drilling OC) do it all on behalf of the consumers' interest" (part of their message IMOW).

[R. Gates]

Rob & Climate changes,

Thanks for the excellent summaries of the annual cycle of methane over the Arctic. I have been especially interested in the increase in NLC's as a result of the methane increase. Their long-term impacts on the upper atmosphere and climate in general are yet to be fully understood.

A4R,

A huge thanks to you for the heads up about methanetracker.org. This will be a fantastic tool and certainly Omar is to be highly commended for his work. Can't wait to use it.

[Apocalypse4Real]

dorlomin stated:

"At the macro level, I can observe, that in February to April,2013 there was a massive release of methane with concentrations above 1950 ppbv that covered the Norwegian, Greenland, Barents and Kara seas, an area larger that the continental United States."

How unusual is this? How many years of this tool do we have to look at?"

I hope the following will help answer your question.

The Barents, Kara, Norwegian Sea methane releases have been observed at 600 mb in the IASI imagery in 2012-2013, for which Dr. Yurganov created images.

He kindly gave permission for the this to be posted at Apocalypse4Real.

For the IASI 600 mb comparison of 2011-2013-2013 YTD, see:

https://sites.google.com/site/apocalypse4realmethane2013/home/iasi-2012-vs-2011-iasi-ch4-970-600-mb

For the IASI 600 mb CH4 comparison of 2008-2009-2010, see:

https://sites.google.com/site/apocalypse4realmethane2012/home/iasi-2008-2011-comparison-970-600-mb

For the IASI 600 mb CH4 comparison for 2010-2011-2012, see:

https://sites.google.com/site/apocalypse4realmethane2012/home/iasi-2012-vs-2011-iasi-ch4-970-600-mb

The AIRS 359 hPa/mb imagery has a longer comparison record, but unfortunately, the imagery is no longer accessible through Giovanni.

The AIRS 359 hPA/mb 2011-2012-2013 comparisons are posted at:

https://sites.google.com/site/apocalypse4realmethane2013/home/2012-vs-2011-airs-ch4-359-hpa

I downloaded the AIRS 359 hPa/mb imagery from Giovanni all the way back to 2002, but have not posted it.

One of my findings is that as Arctic Sea ice melt has increased, the CH4 levels in the atmosphere have continued to increase.

While the METOP 2 IASI imagery only became available in 2012, we now have a tool, with methanetracker.org to track changes globally into the future beginning January 1, 2013.

[Climate Changes]

"long-term impacts on the upper atmosphere and climate in general are yet to be fully understood."

One thing is for sure. During the Hydroxyl process some of the resulting Hydrogen will escape into space never to be seen again. The ice that forms NLC's is destroyed by the same process and the resulting H+H and O are free to recombine or, in the case of the lightest element, move out from this planet. At those stratospheric heights H has no problems dealing with earth's scape velocity, see here: http://en.wikipedia.org/wiki/Atmospheric_escape

Looking at Venus's atmospheric composition we find:

"Hydrogen is in relatively short supply in the Venusian atmosphere. A large amount of the planet's hydrogen is theorised to have been lost to space,[13] with the remainder being mostly bound up in sulfuric acid (H2SO4) and hydrogen sulfide (H2S). The loss of significant amounts of hydrogen is proved by a very high D/H ratio measured in the Venusian atmosphere.[3] The ratio is about 0.025, which is much higher than the terrestrial value of 1.6×10−4.[2] In addition, in the upper atmosphere of Venus D/H ratio is 1.5 higher than in the bulk atmosphere.[2]"

It is very feasable that, if AGW keeps unabated, earth may suffer the same fate as Venus,...

[dorlomin]

"It is very feasable that, if AGW keeps unabated, earth may suffer the same fate as Venus,..."

Don't be silly now.

[Richard Keeling]

It may sound silly, but the climate change that 'Climate Changes' describes is a serious potential scenario. The so-called "Venus Syndrome" is postulated by Dr. James Hansen in his book "Storms of My Grandchildren". There are sound scientific reasons to suggest this might happen. Let's hope they don't come to pass.

[Jai Mitchell]

Venus and AGW

it is a possibility that the earth may experience a runaway warming episode several hundred years from now.

if we do not produce signficant reductions of greenhouse gas emissions in the next 100 years or so it is much more probable that our current global cities will experience catastrophic failure due to sea level rise in the next 200 years.

if we do not produce signficant reductions of greenhouse gas emissions in the next 20 years or so, it is almost certain that our global food production capababilities will experience severe restrictions and this will will lead to significant increased social unrest and possibly societal collapse in the next 65 years.

--just some perspective

[jdallen_wa]

Run away greenhouse warming is highly improbable in less than geological timescales. Even with vastly increased greenhouse gasses, the solar energy budget isn't high enough yet. Ask again in a billion years.

That said, we could see Mesozoic heat levels again, quite easily. However, even with massive input of greenhouse gasses, the transition would take millennia. Far too much stuff to heat up fast, far to slow mechanisms of heat exchange with oceans, permafrost, ice caps, etc.

[dorlomin]

"It may sound silly, but the climate change that 'Climate Changes' describes is a serious potential scenario. "

"Thresholds of type II might be those that are linked directly to the key intrinsic processes of the climate system itself
(often non-linear) and might be related to maintaining stability of those processes or some of the elements of the
climate system discussed earlier. Some thresholds that all would consider dangerous have no support in the literature
as having a non-negligible chance of occurring. For instance, a “runaway greenhouse effect”—analogous to Venus--
appears to have virtually no chance of being induced by anthropogenic activities. "

http://www.ipcc.ch/meetings/session31/inf3.pdf

We can either stick to what is in the scientific literature and accepted, or play the amateur scientist and cherry pick non peer reviewed comments, single outlier studies and guesses from eye balling maps and the like.

I know which route the other side of the mirror use as a modus operandi.

I know which more boring route I will confine myself too.

[Apocalypse4Real]

While I have not read the paper, there is a new publication by James Hansen described in today's Guardian that proposes we are on track for runaway global warming.

See:
http://www.guardian.co.uk/environment/earth-insight/2013/jul/10/james-hansen-fossil-fuels-runaway-global-warming

[Jai Mitchell]

"The problem is that our current global emissions trajectory already commits us to a 2C rise anyway. Papers published by the Royal Society in 2011 showed that emissions pledges would still put the world on track for warming anywhere between 2.5C and 5C - and that a failure to deliver these pledges could see global temperatures rise by 7C by 2100."

http://www.guardian.co.uk/environment/earth-insight/2013/jul/10/james-hansen-fossil-fuels-runaway-global-warming

7C is above some of the estimations of Mesozoic temperatures.

[dorlomin]

"While I have not read the paper, there is a new publication by James Hansen described in today's Guardian that proposes we are on track for runaway global warming."

One single paper that has not been released yet against the vast numbers that have. Including Hansen Sato (2011)?

Hansen seems to be using a burn it all definition to get this. And by all he seems to be lumping in things like kerogen and tar sands. Kerogen is not yet economically viable while tar sands is only able to be produced slowly, we are talking about maybe 6 million barrels a day in around 2025. That rate will take centuries to burn it all.

Worst case fuel use (and astonishingly unlikely possibly impossible) and worst case sensitivity in an outlier paper?

Hmmmm. Things are bad enough without borrowing troubles.

[R. Gates]

While I think it valuable to talk about increases in the growth rates for methane as well as the causes and possible effects of this increase, when one steps into the area of "runaway global warming" and catastrophic sudden release of methane from permafrost and clathrate melt extreme care should be used. I go back to this discussion held on this topic at realclimate.org:

http://www.realclimate.org/index.php/archives/2012/01/an-arctic-methane-worst-case-scenario/

Now there are no doubt certainly unpredictable nonlinear effects that could come from rapid increases in methane releases, much like the nonlinearities we're seeing with the sea ice melt, but talking about runaway global warming and such (even if on the very very unlikely case being true), brings no benefit to trying to speak to the more likely and scientfically justifiable climate effects.

A Pliocene-like or Miocene-like climate is a more reasonable discussion than "we're all going to die as the Earth turns into Venus."

[Hans Gunnstaddar]

Sure, but even if the weather appreciably changes to become anything like the Pliocene or Miocene, does that allow for the type of agriculture and economic environment now supporting and feeding 7+ billion people, with projections of 9-10 billion by mid-century?

I can see how Hansen could get hyperbolic since discussions of climate change have apparently done very little so far to move the yardsticks. He probably feels desperate to describe worse case scenarios since then at least then he will have tried everything.

The frog in an ever increasing temperature pot of water is unaware of its impending plight, and so far the overall attitude of GW is well, sure we know it's probably a problem, but could it really get that bad? Yeah people, unless you want to play musical chairs to see who makes it through the bottle-neck, wake up and go real big on renewables and various forms of CO2 sequestration!

[R. Gates]

Hans,

The questions related to food supplies and general effects on agriculture and ocean food chains are valid when thinking about a potential Pliocene or Miocene-like climate. Certainly some species will benefit and some will not fare so well in a warmer world. Judging by the current rate of species extinction, your concerns are valid in feeding the billions of humans on this planet. There is more common ground that can be found in discussing, "how will we feed 7+ Billion of us." versus "we're all gonna burn up as the world turns into Venus."

[jdallen_wa]

Three big issues will face us:

1) more extreme weather events, with requisite destruction of infrastructure.

2) food shortages, and demand that drives destruction of ecosystems in a frienzy to increase land under cultivation to feed people.

3) massive water resource shortfalls, some persistent, some seasonal, which disrupt agriculture and lead to warfare.

The arctic is one of the first dominos. I am not optimistic. I fully expect the century to end with less than half the population we have currently.

[Superman]

R. Gates,

"Now there are no doubt certainly unpredictable nonlinear effects that could come from rapid increases in methane releases, much like the nonlinearities we're seeing with the sea ice melt, but talking about runaway global warming and such (even if on the very very unlikely case being true), brings no benefit to trying to speak to the more likely and scientfically justifiable climate effects."

I examined the RealClimate link provided, and was not all that re-assured after reading many of the comments. And, we should add to that the paper in December 2012 that announced finding clathrates at 290 M depth, very vulnerable to water temperature changes. If there are sufficient shallow clathrates, their release could trigger some of the other positive feedback mechanisms that are cross-coupled synergistically through temperature, with highly nonlinear impacts.

Think of the bigger picture here. All the credible governmental, intergovernmental, and industry projections of energy use have fossil use INCREASING over the next two-three decades. With business-as-usual, the global climate models predict ~5-6 C by the end of the century. Mark Lynas, in his book Six Degrees, predicts at those temperature levels many species go extinct, including ours. And, these global climate models don't include the major positive feedback mechanisms, so real-world effects will accelerate when we experience 5-6 C.

The point is, we don't need Venusian-style runaway global warming. A modest acceleration that brings 6 C within our children's or grandchildren's lifetime will be as effective as reaching Venusian conditions.

[dorlomin]

290 M depth, very vulnerable to water temperature changes

290 meters is an incredible amount of water to warm.

Only 100 000 years ago we were 1.5C warmer without a major calamity.

Past clatherate releases seem to take in the order of 1000s of years to respond to the warming.

You can make a case 'this time is different' but it has to built on sound numbers, properly modeled oceanography and so on.

The earth is huge, permafrost is very slow to defrost, oceans are deep and have enormous thermal inertia.

[BertocchiDanilo]

Hi dear All, I read the paper of Hansen. This reinforcing the opinion we are facing a major challenge. Randers, Steffen, Savory. Aleklett, are writing in the same direction. Holistic approach help to understand the present situation. We are completely locked. Demography is key. Global guidelines to make one child, especially in the rich world, setting renewable power plants in poor world would help.

[Hans Gunnstaddar]

R. Gates: There is more common ground that can be found in discussing, "how will we feed 7+ Billion of us." versus "we're all gonna burn up as the world turns into Venus."

Agreed. I do not adhere to the Venus bit either.

[Hans Gunnstaddar]

Superman, what about the idea that as fresh water melt increases reducing salinity, the THC can switch into an ice age?

[mabs]

Here is a link to Hansen's paper. I'm not sure how close it is to the version to be published in "Philosophical Transactions," but the summary in the Guardian fits... somewhat.

http://arxiv.org/ftp/arxiv/papers/1211/1211.4846.pdf

I'm not an expert on this topic, so some of the finer points might have gone over my head, but I don't think that the main point of the paper is to discuss the Venus effect, which he clearly states is not likely; not for a few billion years when the sun gets a lot brighter than today. He also dismisses the possibility that a mid-range runaway greenhouse effect, a.k.a "moist greenhouse," is possible.

"Similarly, a Venus-like baked-crust CO2 hothouse is far distant because it cannot occur until the ocean escapes to space. We calculate an escape time of order 10^8-10^9 years even with the increased stratospheric water vapor and temperature at 16×CO2. Given the transient nature of a fossil fuel CO2 injection, the continuing forcing needed to achieve a terminal Venus-like baked-crust CO2 hothouse must wait until the Sun's brightness has increased on the billion year time scale." (p. 17 - in the link)

Rather, the point of the paper is to get a more accurate estimate of climate sensitivity (he lost me here on a few things), with special consideration to how it may vary across climatic states.

Based on those estimates, and making a series of assumptions about CO2 levels, Hansen does say that a "low-end greenhouse effect," which, as far as we are concerned, would render the planet mostly uninhabitable.

"On the other hand, conceivable levels of human-made climate forcing could yield the low-end runaway greenhouse. A forcing of 12-16 W/m2, which would require CO2 increase by a factor of 8-16 times, if the forcing were due only to CO2 change, would raise global mean temperature by 16-24°C with much larger polar warming. Surely that would melt all the ice on the planet, and likely thaw methane hydrates and scorch carbon from global peat deposits and tropical forests. This forcing would not produce the extreme Venus-like baked-crust greenhouse state, which cannot be reached until the ocean is lost to space. Warming of 16-24°C produces a moderately moist greenhouse, with water vapor increasing to about 1% of the atmosphere's mass, thus increasing the rate of hydrogen escape to space. However, if the forcing is by fossil fuel CO2 the weathering process would remove the excess atmospheric CO2 on a time scale of 104-105 years, well before the ocean is significantly depleted. (p. 24; my emphasis)

What is interesting (if I understood his point correctly) is that, within the model's parameters, it is not necessary to burn all remaining fossil fuels to get a low-end runaway greenhouse effect.

[Jai Mitchell]

Thanks Mabs

He says explicitly that we will have to wait a billion years for the runaway venus effect (warmer sun). He then goes on to say that,

"The airborne fraction, observed to have been 55% since 1950 (IPCC, 2007a), should increase because of well-known non-linearity in ocean chemistry and saturation of carbon sinks, implying that the airborne fraction probably will be closer to two-thirds rather than one-third, at least for a century or more. Thus the fossil fuel source required to yield 9 W/m2 forcing may be closer to 5,000 GtC, rather than 10,000 GtC."

Which means, basically that the amount of natural sequestration of carbon will reduce so that an additional 11% of annual human emissions will remain in the atmosphere each year within the next few decades.

This is just one of may feedbacks that are likely to occur.

in the end he says basically, that it will only take about half as much additional fossil fuel sourced CO2 (5,000GTC) to produce catastrophic warming of up to 9'C (due to permafrost and clathrate feedbacks)

[Superman]

Hans,

"Superman, what about the idea that as fresh water melt increases reducing salinity, the THC can switch into an ice age?" Some researchers have viewed that as a possibility, with colder temperatures coming to North America and Europe. I haven't examined that effect sufficiently to comment further.

[dorlomin]

Superman, what about the idea that as fresh water melt increases reducing salinity, the THC can switch into an ice age?

The idea comes from Wally Broecker, one of the true giants in the field, as an explanation for an extreme short sharp cooling at the end of the last ice age called the Younger Dryas. But that required a huge lake bursting through its ice damn.
http://www.ldeo.columbia.edu/res/div/ocp/gs/pubs/broecker_science.pdf

It is possible but worth remembering that the 'prevailing westerlies' wind pattern is also partially responsible.

So far as I have seen the current thinking is that this will not be a big problem over the medium term as there is unlikely to be a big enough surge of fresh water.

[Apocalypse4Real]

methanetracker is revealing significant releases of methane in the East Siberian Sea as the sea ice melts and releases high concentrations of methane, likely from clathrates, that was trapped beneath the ice.

There is a methane release above 1950 ppbv in the East Siberian Sea that has persisted as the sea ice has melted or moved over the last three days.

Beginning 7 July 2013 pm it developed across the area between 150-165E and 71 30 and 76 N. There is a major burst on July 9-10, between 151-156 E and 71 15 - 72 45 N or an area approximately 75x100 miles that persists for 36 hours, which seems like clathrate methane release by melting ice.

I used the methanetracker unified layers set for two days and SSMIS sea ice layer to follow the changes in methanetracker.org.

[Hans Gunnstaddar]

Apocalypse4Real, I found these links on an oil drum.com post today:

Here are two must see Youtube videos by Omar Cabrera on methane releasing via methanetracker.org

1) http://www.youtube.com/watch?v=E1OluDXNXJ4

2) http://www.youtube.com/watch?v=j_xaifA5-wI

Watch them in order and what you’ll see is large plumes of methane releasing off the coast of Norway over to Greenland and in Siberia, but also later in the Sahara and Gobi desert plus a desert in Chile. Then in the 2nd video it shows huge plumes rising from Antarctica. The question is has this level of methane always been releasing or is more releasing in recent years?

I'm also wondering why methane would release from deserts?

[Rob Dekker]

I did a quick back-of-the-envelope calculation of the radiative forcing variation of methane concentration between summer and winter.

Bare with me here.

Methane (CH4) has a 72x greenhouse potential versus CO2, by mass.
By volume that is a factor of 16/48 x 72 = 24x.

Using 3.7 W/m^2 forcing per doubling of CO2, a change of 1 % is methane by volume should thus result in about 0.9 W/m^2 forcing.

Now, the NOAA graph shows methane variation over the Arctic in winter of about 1920 ppb, and in summer of about 1860. That is a 3.2 % variation.

That suggests that the greenhouse forcing in winter is about 2.8 W/m^2 larger than in summer (and maybe even more amount above global averages).

That's quite substantial !

Since greenhouse gas forcing in winter drives up winter freezing temps, and thus determines ice thickness for the next melting season, I wonder if GCMs include this effect in their modeling of Arctic sea ice projections....

[Rob Dekker]

Continuing on that line of thought, global average methane concentration in the atmosphere is about 1790 ppb or so.

Compared with the winter Arctic methane concentration of 1920 from NOAA, that represents a 7.3 % higher concentration of methane over the Arctic than the global average, and thus a 6.6 W/m^2 difference in forcing.

That is more than substantial, and I wonder if IPCC GCMs underestimates of Arctic ice loss take that effect into account...

[Kate]

Since I really like looking at data visually, can someone explain or debunk the idea that you can see concentrations of methane by a very light sky blue? I've heard somewhere that methane in high concentrations makes the sky very very light blue - is this right? Because you can see sometimes very light blues in the arctic webcams and from the Healy. Am I wrong to think this is methane?

[Kevin McKinney]

"At room temperature and standard pressure, methane is a colorless, odorless gas."

And concentrations are really low...

So, though I don't really know, I'm inclined to doubt that variations of a couple of hundred parts per billion have any effect at all on perceived sky color.

[dorlomin]

@Rob Dekker
By volume that is a factor of 16/48 x 72 = 24x.

I am sorry but what are you saying?

CO2 is about 390 ppm
CH4 is around 1.9ppm.
Where does 16/48 come from?

[dorlomin]

@Apocalypse4Real
methanetracker is revealing significant releases of methane in the East Siberian Sea as the sea ice melts and releases high concentrations of methane, likely from clathrates, that was trapped beneath the ice.

Do you have any evidence of this being trapped beneath sea ice?

Ice if full of cracks and holes and that much volume beneath the ice would have made it much more buoyant and it would be hard for any science expedition in the area to miss giant volumes of methane beneath ice.

[Apocalypse4Real]

Hi Rob,

Thanks for the mathematics on CH4 forcing, it is interesting to see. If you'd like a more detailed picture of variation from part of the Arctic at 600 mb, see the graphs posted at:

https://sites.google.com/site/apocalypse4realmethane2013/

It provides Dr. Yurganov's IASI measurements of regional methane concentrations in the Barents and Norwegian seas for parts of 2008-2013.

In regard to global methane average concentration, it depends on the layer in the atmosphere. For example, July 11 2013 12-24 hr Z at 206 mb the global methane mean was 1789 ppbv.

On the other hand, between approx. 400-766 mb, the methane mean was at or over 1800 ppb, with the highest being 1804 ppbv.

This spring, with the major releases in the Barents, Norwegian and Kara seas, with perhaps the high concentrations in Antarctica, the global mean went over 1800 ppbv for the first time. We will see if that holds through the year, as I anticipate it will.

So there is quite a bit of variation.

[Kevin McKinney]

"Do you have any evidence of this being trapped beneath sea ice?

"Ice if full of cracks and holes..."

I'd have thought that the fact that the sea ice forms an imperfect 'lid' does not negate the fact that it does form a 'lid'... IOW, surely some portion of any methane release from the sea water would be held under the ice?

On the other hand, I'd imagine that the warming of the sea water following upon ice melt and subsequent insolation should result in some outgassing of dissolved methane, too. And the sequence of events sounds suggestive, even if the old saw about 'correlation' still applies.

[dorlomin]

@Kevin McKinney
in some outgassing of dissolved methane

Many things are suggestive of many things. But given the volumes we are talking about here are they not going to be a bit more obvious than suggestive?

Has anyone actually observed this methane being trapped right under the sea ice?

[Kevin McKinney]

Appreciate the (real) skepticism, Dorlomin.

"But given the volumes we are talking about..."

What volumes are we talking about? Has anybody quantified this beyond "significant releases?"

(Goes off to actually look at methanetracker.)

[Apocalypse4Real]

Hans,

Its great that you appreciated Omar's videos about methanetracker.org and what we are finding in the imagery.

We have not had the METOP 2 IASI data availability before late 2012, and methanetracker.org is using data beginning January 1, 2013. So how the methane release globally compares at this level of detail is not yet known.

We do know from other studies and Dr. Yurganov's imagery that at either 350 mb for the AIRS images, and 600 mb for the METOP A IASI that the Arctic releases have been increasing since 2002.

In regard to high methane concentrations in desert areas in summer, I am still learning about this, since observing it in the METOP 2 IASI imagery. Once overlaid in Google Earth, some sources seem to be oil or natural gas extraction. However, much of it seems related to rainfall events that trigger release, perhaps from soils. This is something I am still working on. Once released, the concentrations are generally in the upper atmosphere.

Rob,

Thanks for the math on the CH4 radiative forcing, it was very interesting. There is significant variation in the global mean methane levels depending on the level in the atmosphere, and perhaps, time of year.

Right now, for example, the METOP 2 IASI imagery reveals a mean as high as 1800 ppbv from approx. 400 mb down to 766 mb, with it ranging as high as 1804 ppbv.

[Apocalypse4Real]

dorlomin,

Methane sourced from subsea clathrates has been documented being frozen in sea ice in the Laptev and elsewhere during the onset of winter.

Its release from the ice during thawing has been documented by HIAPER/HIPPO.

For a picture and comments by Semelitov, see: http://www.popsci.com/science/article/2010-03/vast-amounts-frozen-methane-escaping-atmosphere-leak-arctic-seafloor

For the HIPPO flight comments, see:

http://www.jpl.nasa.gov/news/news.php?release=2012-110

My observations are from use of methanetracker.org, on July 7-11, turning on multiple layers of CH4 while displaying the SSMIS sea ice layer changes.

As the sea ice melted, the methane levels went above 1950 ppbv in that area. I'd welcome your working with methanetracker.org to see for yourself. The possibilities seem to be sea ice melt, or methane generation by plankton, etc, for a short period of time during sea ice melt.

I'll post a photo from the 2007 ESAS expedition of the bubbles locked in sea ice in the Permafrost section of the Forum.

[Kevin McKinney]

No luck with methanetracker; the system I'm on right now is too old, I think.

But some searching found this paper, which is interesting, and partially relevant, as it concerns the permeability of sea ice (though it does not address methane per se.)

http://www.sciencedirect.com/science/article/pii/S0924796306001862

More recently, there was this review:

https://darchive.mblwhoilibrary.org/handle/1912/4916

Ah! The PDF is here:

https://darchive.mblwhoilibrary.org/bitstream/handle/1912/4916/24-3_loose.pdf?sequence=1

There's a lot of interesting stuff on CO2 fluxes within/across/to/from sea ice, but little about methane. However:

"...methane... is produced in anoxic sediments and is often found trapped in bubbles under sea ice (Kvenvolden et al., 1993; Shakhova et al., 2009.)"

So, yes, methane trapped under sea ice apparently has been observed. However, the assumption that it must be from clathrates is not necessarily correct; the methane may be biogenic instead.

[Tor Bejnar]

mabs quotes Hansen: "...if the forcing is by fossil fuel CO2 the weathering process would remove the excess atmospheric CO2 on a time scale of 104-105 years, well before the ocean is significantly depleted."

It took me a moment to figure out that "104-105 years" is 10^4 - 10^5 years, or 'on the order of tens of thousands to hundreds of thousands of years'

Richard Alley talks about this geological CO2 control in his 2009 lecture The Biggest Control Knob: http://www.agu.org/meetings/fm09/lectures/lecture_videos/A23A.shtml

[dorlomin]

@dorlomin
would have made it much more buoyant

Wrong. This seems to be a change of around 150 ppb in the atmosphere. The mass of the atmosphere is about 10 000kg per square meter. CH4 weighs less than O2 and N2 but within the same order of magnitude so I will assume equal mass per molecule and its about 1.5 grams per square meter.

A cubic meter of water is around 1 tonne so 1.5 grams is not going to affect buoyancy.

Silly me.

[mabs]

@Tor

Thanks for the correction. It looks like I missed that one.

[dorlomin]

@Apocalypse4Real
Methane sourced from subsea clathrates has been documented being frozen in sea ice in the Laptev and elsewhere during the onset of winter.

There is some but it is enough, where does it come from, how widespread is it, how long has this been happening, i.e. are we simply seeing something that has existed for many years?

As the sea ice melted, the methane levels went above 1950 ppbv in that area.

Sea ice melts from around April there. This is the time the whole region experiences its methane maximum for the year. Have you thought that these variations may be due to more regional factors rather than what is immediately below?

What you have is an interesting observation. Now you will have to do the hard yards to turn it into a hypothesis. That means lots of work to eliminate the alternatives and contextualise it (i.e. is this just something that has been happening for decades or centuries or is it new and if so why is it happening)?

I am not riding you hard to be a pain, but these are the sort of questions our 'friends' on the other side of the mirror will have for you in a much much more hostile fashion.

[D]

@ delormin. Rob was saying that by mass, CH4 has a GH potential effect that is 72 x greater than CO2 but by volume the effect is only 24. The molecular mass of CH4 is 16 and the mass of CO2 is 44 (@ Rob.... Did you make a typo by using 48? ) Since one mole of any gas will have a volume of 22.4 L @ STP, one needs to compare mole volumes and not mass. Rob's fraction of 16/48 (should be 16/44) gets you there.
Back to lurking for me.

Windchaser

[Rob Dekker]

Windchaser, dorlomin.
Sorry guys, I messed up. You are both right.
Let me try again, this time corrected :

CH4 by mass has a GH potential 72x greater than CO2. By volume (by mole, or molecule count), that GH potential is 72 * 16/44 = 26x, since we need to adjust for the molecular mass fraction between CH4 (16) and CO2 (44)

If a doubling of CO2 in the atmosphere will cause 3.7 W/m^2 forcing, a doubling of CH4 will cause 3.7 * 26 * 1.9/390 = 0.47 W/m^2 forcing, since we need to adjust for the volume fraction in the atmosphere between CH4 (1.9 ppmv) and CO2 (390 ppmv).

So forcing for a doubling of CH4 is only 0.47 W/m^2. Did I do that right now ?

If so then the variation of 3% CH4 over an annual cycle will thus cause a negligent variation in radiative forcing over the Arctic.

[Bdwo]

Natural marine seepage blowout: Contribution to atmospheric methane; Ira Leifer, Bruce P. Luyendyk, Jim Boles, and Jordan F. Clark doi:10.1029/2005GB002668.
http://www.geol.ucsb.edu/faculty/luyendyk/Luyendyk_pdf/Leifer_etal_GBC_06_SeepBoom.pdf - cool pictures; I think "SeepBoom" in the URL indicates the authors position on the wisdom of poking clathrates with rising CO2 emissions.
"On 8 March 2002, SCUBA divers were at Shane Seep to measure the bubble plume’s upwelling flow velocity, Vup, the velocity water moves vertically owing to the rising bubbles, by introducing fluorescein dye into the bubble stream at the seabed and measuring its time of arrival at the sea surface [Clark et al., 2003]. Video cameras were situated at the seabed and 5 m above, at the sea surface, and in an airplane. A test dye release at 0845 Local Time (LT) yielded a 50-s transit time, Vup
44 cm s1, comparable to previous values [Clark et al., 2003]. Ten minutes before the airplane’s arrival, divers reported that seabed seepage at the main HC volcano had virtually ceased (Figure 2a). At 0936 LT a large gas ejection occurred at the seabed (Figures 2b and 2c). Suddenly, three separate gas streams arose from the seabed, described by the divers as sounding like a freight train. The leading bubbles expanded very rapidly to several meters in diameter by 5 m above the seabed. Dye introduced into the bubble flow at the seabed a few seconds after the blowout (Figure 2d) first was observed at the sea surface
7 s later (Figure 2e), peak Vup
300 cm s1, while the main mass of dye arrived
10 s after dye injection, Vup
200 cm s1. Bubble plumes lift deeper, cooler water that forms a divergent outward flow of water at the sea surface. During the blowout, the area of outward flow expanded rapidly (Figure 2f). Overflight images showed the dyed bubble stream transversing the water column, tilted by the currents (Figures 2g and 2h)." Note that the dye arrives with the entrained water, not the first gas bubbles. My back of envelope calculations using 40 cm/sec indicate that a 100 meter diameter methane "fountain" entraining water 1 degree above melting(e.g., from the layer of Atlantic Water that penetrates the arctic below the fresher surface layer) could carry enough heat to melt an ~ 1 km diameter hole in 1 meter thick ice per month. Of course, what goes up must come down, and the turnover could transfer heat from solar warmed surface water back to the bottom as the melt season progresses.

Warming the fuel for the fire: Evidence for the thermal dissociation of methane hydrate during the Paleocene-Eocene thermal maximum; Thomas et al - doi: 10.1130/0091-7613(2002)​030<1067:WTFFTF>​2.0.CO;2 Geology, v. 30 no. 12 p. 1067-1070
http://geology.gsapubs.org/content/30/12/1067.abstract
"We present new high-resolution stable isotope records based on analyses of single planktonic and benthic foraminiferal shells from Ocean Drilling Program Site 690 (Weddell Sea, Southern Ocean), demonstrating that the initial carbon isotope excursion was geologically instantaneous and was preceded by a brief period of gradual surface-water warming. Both of these findings support the thermal dissociation of methane hydrate as the cause of the Paleocene-Eocene thermal maximum carbon isotope excursion. Furthermore, the data reveal that the methane-derived carbon was mixed from the surface ocean downward, suggesting that a significant fraction of the initial dissociated hydrate methane reached the atmosphere prior to oxidation."

An Ancient Carbon Mystery, Mark Pagani, Ken Caldeira, David Archer, James C. Zachos Science 8 December 2006: Vol. 314 no. 5805 pp. 1556-1557 DOI: 10.1126/science.1136110
http://www.sciencemag.org/content/314/5805/1556.full
"According to one hypothesis, the PETM was caused by the release of ∼2000 PgC from the destabilization of methane hydrates (which would subsequently oxidize to form CO2) (10). However, it is unlikely that methane was the sole source of warming. For example, the size of the methane hydrate reservoir at the end of the Paleocene was probably much smaller than it is today (11), and the magnitude of the sustained warming and the change in the carbonate compensation depth are compatible with a much greater mass of carbon than originally estimated (6). To account for larger carbon inputs, other sources have been invoked, including the oxidation of terrestrial (12) and marine (13) organic carbon and/or volcanic outgassing and thermal decomposition of organic matter (14). There is no single satisfactory explanation."

Will the current rapid warming as opposed to gradual PETM surface-water warming have a lower or higher threshold for triggering a "geologically instantaneous" release of CH4? Do the differences in seafloor configuration, ocean circulation, methane hydrate amounts, background CO2 levels, and other unknown unknowns raise or lower the threshold for triggering the clathrate gun? If you keep pushing on a trigger to find the force required, eventually you will reach it. Given the unknowns and uncertainty, we could get lucky. Being as this is a 1400 Gt Magnum, the most powerful GHGgun in the world, and would blow most everybodies head clean off, you've got to ask yourself one question: Do I feel lucky? Well, do ya, punks? (apologies to Clint Eastwood as Dirty Harry)

Dietary controls on extinction versus survival among avian megafauna in the late Pleistocene Geology, Kena Fox-Dobbs, Thomas A. Stidham, Gabriel J. Bowen, Steven D. Emslie, and Paul L. Koch August, 2006, v. 34, p. 685-688, doi:10.1130/G22571.1
http://geology.gsapubs.org/content/34/8/685.abstract
"The late Pleistocene extinction decimated terrestrial megafaunal communities in North America, but did not affect marine mammal populations. In coastal regions, marine megafauna may have provided a buffer that allowed some large predators or scavengers, such as California condors (Gymnogyps californianus), to survive into the Holocene."

Are homo (notso)sapiens megafauna? Will we come to regret so many seals were killed(reducing or eliminating populations) just to make fur coats instead of keeping them around for food?
What are we prepared to do if the scientists tell us "X was the clathrate gun trigger threshold that we have already passed"?

[Robertscribbler.wordpress.com]

We should find out if these are outliers over the next week or so. In any case, there are quite a few methane sources showing up in the Arctic these days. And it's not helping in the least that fracked wells are also leaking at rates of about 4-8 percent...

Methane's kick to warming is pretty strong and paleoclimate shows it's not really a beast you want to let loose.

[Hans Gunnstaddar]

Bdwo writes: "Being as this is a 1400 Gt Magnum, the most powerful GHGgun in the world, and would blow most everybodies head clean off, you've got to ask yourself one question: Do I feel lucky? Well, do ya, punks?"

Hans writes: "Could there be a connection between the spice (emitting carbon) and the worm (runaway GW)?"

"Ah, in spite of all the screaming and hollering (AGW debate) they come in and rip you to pieces (climate change consequences)."

"Oh Auntie Em, there's no place like Home!" (low amplification, 1939).

Bdwo asks: What are we prepared to do if the scientists tell us "X was the clathrate gun trigger threshold that we have already passed"?

Answer: Debate it to a stalemate, between a climatologist with a PHD and Masters degree against a high school drop out lawn furniture salesman.

[Wipneus]

" So forcing for a doubling of CH4 is only 0.47 W/m^2. Did I do that right now ? "

From a previous discussion:
http://neven1.typepad.com/blog/2011/12/arctic-methane-russian-researchers-report/comments/page/2/#comments

a link to RC:
http://www.realclimate.org/index.php/archives/2010/12/losing-time-not-buying-time/

You are getting closer, Raypierre gives a value of 0.8 W/m2 per doubling.

[Rob Dekker]

Thanks Wipneus, for digging up that RC reference.
Raypierre writes :

For example, doubling CO2 from 300 ppm to 600 ppm yields a clear-sky radiative forcing of 4.5 W/m2. Doubling methane from 1ppm to 2 ppm yields a radiative forcing of 0.8 W/m2, but since we started from such a low concentration of methane, it takes many fewer molecules of methane to double methane than to double CO2. Per molecule added, methane yields about 54 times as much radiative forcing as CO2.

Obviously now I'm interested why the estimates differ.

He uses 4.5 W/m^2 for CO2 (that is higher than my 3.7 because he uses clear sky forcing, while my 3.7 is the average for all weather all across the planet), so that difference is explainable.

But then he uses a multiplier of 54 per molecule (so that is by volume).
That would be 54 * 44/16 = 148.5 by mass, which sounds awefully high compared to my multiplier of 72 by mass.

Let's see if we can reproduce his number (0.8 W/m^2 for a doubling of methane) from the CO2 forcing, his CH4/CO2 GHG potential multiplier and the volume fraction of methane/CO2 in the atmosphere :

4.5 * 54 * 1.9/390 = 1.18 W/m^2.

Even if I lower CO2 forcing to 3.7, I still can't reproduce his 0.8 W/m^2 number.

Obviously there is something wrong with his multiplier, or my formula is still incorrect.

Darn. This is supposed to be simple. What am I doing wrong ?

[Wipneus]

Forcings are proportional to log(concentration), so a doubling of methane from 1->2 ppm, compared with CO2 concentration of 390->391 ppm gives a forcing ratio of:

(log(2)*.8)/(log(391/390)*4.5) = 48.1

close enough to 54?

[Yuha]

According to IPCC (Table 2.1, p. 141 in WG-1) the rise of methane levels from pre-industrial 715 ppb to 2005 level of 1774 ppb has had a radiative forcing of 0.48 W/m^2.
Based on that the radiative forcing of doubling methane level is:

0.48*ln(2)/ln(1774/715) = 0.366 W/m^2

The same calculation for CO2 gives:

1.66*ln(2)/ln(379/278) = 3.71 W/m^2

which agrees with Rob's 3.7.

[Yvan Dutil]

Yuha, your calculation is wrong. Ulike CO2, methane is only semi saturated. The forcing does not follow a logarithm, but some polynomial. Hence, the impact is larger than your calculation.

[dorlomin]

@Rob Dekker
If so then the variation of 3% CH4 over an annual cycle will thus cause a negligent variation in radiative forcing over the Arctic

Cheers for that Rob. I thought your original number was a bit off, guess we have all kind of reached about the same broad conclusion in the end.

[Jai Mitchell]

not sure where you get the 54 multiplier. The GWP of methane starts at 100 times (on a 5-year scale) and drops to 20 times on a 100 year time scale.

http://i245.photobucket.com/albums/gg46/SamCarana/5365879809.jpg

[Jai Mitchell]

sorry, meant to post this link: http://arctic-news.blogspot.com/p/arctic-methane-alarm.html

[Robertscribbler.wordpress.com]

To address the points about a runaway and Earth turning into Venus...

Hansen notes there are three levels of runaway.

1. A 'mini runaway' like the PETM that would result in temps 10-15 C hotter than now and, probably, a mass extinction in the oceans.

2. A moist stratosphere runaway that would result in temps around 25 C hotter than now, massive ozone depletion and the only habitable regions being the high mountains.

3. A Venus runaway where all the oceans evaporate and the crust bakes its carbon load out.

1&2 are reasonably possible given a large methane pulse and are almost certain to happen if we burn all the fossil fuels (Hansen). But such events are likely to come at the tail end of any AGW nightmare scenario. 3 is likely not possible except in the 100 million to 1 billion year timeframe.

The reason why added methane release from the Arctic is a concern is that the Arctic is now becoming a methane/carbon source that makes limiting warming in this century by 2 degrees C or less a very difficult proposition. Large pulses of methane are, therefore, a very dangerous amplifying feedback to human caused climate change. That such pulses may be happening on some scale now is definitely cause for very serious concern even though it's not likely to turn us into Venus anytime soon.

[Yuha]

Yvan, thanks for pointing out my error.

I found the correct formulas in IPCC 3rd assessment report (Table 6.2) and did some calculations and plots.

It turns out that the radiative forcing of methane is nearly linear in the range 1700-2200 ppb, approximately 0.35 W/m^2/ppm.

That is, each additional 100 ppb of methane increases radiative forcing by about 0.035 W/m^2.

[Ned Ward]

As I understand it, methane (at Barrow, and elsewhere) is increasing at around 0.3% per year. That's certainly faster than it was a few years ago, but it's nothing like the rates from the 1970s, when CH4 was increasing at about 1.7% per year.

[R. Gates]

Ned Ward,

You are right about the growth rate for methane coming down from where it was in the 70's. Back then, methane was flared off during oil extraction and not seen as commercially useful. Now of course, that has changed and the methane is captured, sold, and eventually burned and released into the atmosphere as CO2. Recently (as in the past few years) the growth rates for methane have started to inch back up, though they are still not at the levels seen before they stopped flaring methane off. Now, as discussed on the blog and in so many other places, it appears that the new uptick in methane growth could be related to a warming Arctic and the melting of permafrost, clathrates, etc. A good article on methane growth rates can be found here:

http://www.nature.com/scitable/knowledge/library/methane-hydrates-and-contemporary-climate-change-24314790

and here:

http://www.nasa.gov/topics/earth/features/earth20120828.html

[Steve Bloom]

Interesting times:

Title: Offshore permafrost decay and massive seabed methane escape in water depths >20 m at the South Kara Sea shelf

Abstract: Since the Last Glacial Maximum (~19 ka), coastal inundation from sea-level rise has been thawing thick subsea permafrost across the Arctic. Although subsea permafrost has been mapped on several Arctic continental shelves, permafrost distribution in the South Kara Sea and the extent to which it is acting as an impermeable seal to seabed methane escape remains poorly understood. Here we use >1300 km of high-resolution seismic (HRS) data to map hydroacoustic anomalies, interpreted to record seabed gas release, on the West Yamal shelf. Gas flares are widespread over an area of at least 7,500 km2 in water depths >20 m. We propose that continuous subsea permafrost extends to water depths of ~20 m offshore and creates a seal through which gas cannot migrate. This Arctic shelf region where seafloor gas release is widespread suggests that permafrost has degraded more significantly than previously thought. (Emphasis added.)

I haven't read the paper yet, but the apparent consistency of the effect relative to depth would seem to point the finger at warm water encroaching onto the shelf. That interpretation seems consistent with the supplemental map of the surveyed area, the legend for which reads:

Map showing the distribution of gas flares (yellow lines), neotectonic faults (black lines), and sands/silty sands at the seafloor (grey areas). There appears to be no correlation between the presence of flares and the occurrence of faults and/or coarse-grained sediments at the seafloor. In fact, the majority of flares occur in regions of the seafloor where sediments are comprised mostly of silts and clays. This suggests that there is a different geological control on the distribution of gas flares in the area.

[Hans Gunnstaddar]

http://www.npr.org/blogs/krulwich/2013/01/30/170661670/pale-blue-blobs-invade-freeze-then-vanish

Great pic of methane bubbles in lake ice.

[Boa05att]

Huge methane belch in Arctic could cost $60 trillion

http://www.newscientist.com/article/dn23923-huge-methane-belch-in-arctic-could-cost-60-trillion.html#.Ue_Owm0bjLo

Full paper here:
http://www.nature.com/nature/journal/v499/n7459/pdf/499401a.pdf?WT.mc_id=TWT_NatureClimate

[Boa05att]

Here's an interview with Prof. Wadhams about this new paper:

http://www.guardian.co.uk/environment/earth-insight/2013/jul/24/arctic-ice-free-methane-economy-catastrophe