Methane Bomb Squad Part 5: Shakhova, Schmidt

October 20, 2014

UPDATE: a reader sends a link to a more recent (june 2014) Shakhova interview. The sound quality not as good, which makes it difficult to follow, nevertheless,I am posting this in the interest of furthering the discussion.  This is a “part 1” of 3, the others being available at the you tube link.

In the past week, I’ve been posting a number of excerpted interviews relating to the topic of undersea methane releases in the arctic.
This has not actually been something I planned out just this way. The idea was, I wanted to interview as many folks behind the scenes and find out as much as I could, then synthesize everything into a nice tidy video, and release that. But events have kind of overtaken that.

In September, the Royal Society held an event in the UK which drew a number of experts on arctic ice and the rapid changes observed there. Among those was Dr. Gavin Schmidt, of NASA, one of the most highly respected experts on the planet in areas of global climate. Dr. Schmidt gave a well attended lecture on the issue of arctic methane, specifically to push back against what has become somewhat of a Youtube cottage industry, methane disaster porn.   It’s not hard to  find  material proclaiming the imminent extinction of humanity due to the massive release of methane from arctic ocean shelves – and I agree with Dr. Schmidt that this kind of material is irresponsible and divorced from reality.

The scientific source often cited (and then, I think, exaggerated) for such dire pronouncements is the work of Dr. Natalia Shakhova, the University of Alaska in Fairbanks, and her associate Dr. Igor Semilitov.  Short story, Shakhova et al were not at the UK shindig, leading to charges of conspiracy to exclude them from the discussion.  Since I started this series, I’ve even been getting emails darkly hinting that perhaps I was a tool of that conspiracy, as well.  I don’t think a preference to step carefully is indicative of a conspiracy, but never mind.

Among Dr. Schmidt’s strongest arguments are datasets that he says indicate little or no methane breakout in the relatively near paleo-record, from 2 previous eras.
First, the Holocene warm period, –  at about the time the planet was coming out of the last ice age, the arctic was warm, possibly warmer than today, for a period substantially longer than the current warmup.  The other period, known as the Eemian, was an interglacial, a temperate spell, like ours, just before the plunge in to the most recent ice age, about 120,000 or so years ago.  We know it was pretty warm for quite a while – thousands of years – because sea level was high – maybe 15, or 20 feet higher, and a substantial portion of the Greenland ice sheet seems to  have melted.
Yet, Schmidt says, we saw no methane breakout.
This paleo argument is compelling to me, as I have always considered the fossil record a powerful indicator of how the current climate will behave.

Could we have more of a buffer for big methane belches than we know?  Here are two slides from Schmidt’s lecture – which is not available to my knowledge online, although may be soon, at least in audio.

eemian

holocene

 

There’s a lot more material on this, much of which I have not digested myself, but I wanted to get as much of this under-seen and under-discussed material online where people can read it, and spark a tiny bit more informed discussion on the issue, something I am sure Dr. Schmidt, Dr. Shakhova, and all concerned, would like to see happen.  There are a lot more perspectives on this than what most people have heard, so now is as good a time as any to hear them.
Clearly this is an important discussion, and more information is needed. Happy to hear from anyone who has additional useful resources on this issue, and ideas about how to broaden the discussion.

RealClimate blog posted a review of the issue, I’m assuming by David Archer, about a year ago:

Methane from the Siberian continental shelf

The Siberian continental shelf is huge, comprising about 20% of the global area of continental shelf. Sea level dropped during the last glacial maximum, but there was no ice sheet in Siberia, so the surface was exposed to the really cold atmosphere, and the ground froze to a depth of ~1.5 km. When sea level rose, the permafrost layer came under attack by the relatively warm ocean water. The submerged permafrost has been melting for millennia, but warming of the waters on the continental shelf could accelerate the melting. In equilibrium there should be no permafrost underneath the ocean, because the ocean is unfrozen, and the sediment gets warmer with depth below that (the geothermal temperature gradient).

Ingredients of Shakhova et al (2013)

  1. There are lots of bubbles containing mostly methane coming up from the shallow sea floor in the East Siberian Arctic shelf. Bubbles like this have been seen elsewhere, off Spitzbergen for example (Shakhova et al (2013)). Most of the seep sites in the Siberian margin are relatively low flow but a few of them are much larger.shakhova
  2. The bubbles mostly dissolve in the water column, but when the methane flux gets really high the bubbles rise faster and reach the atmosphere better. When methane dissolves in the water column, some of it escapes to the atmosphere by evaporation before it gets oxidized to CO2. Storms seem to pull methane out of the water column, enhancing what oceanographers call “gas exchange” by making waves with whitecaps. Melting sea ice will also increase methane escape to the atmosphere by gas exchange. However, the concentration of methane in the water column is low enough that even with storms the gas exchange flux seems like it must be negligible compared with the bubble flux. In their calculation of the methane flux to the atmosphere, Shakhova et al focused on bubbles.
  3. Sediments that got flooded by rising sea level thousands of years ago are warmer than sediments still exposed to the colder atmosphere, down to a depth of ~50 meters. This information is not directly applied to the question of incremental melting by warming waters in the short-term future.
  4. The study derives an estimate of a total methane emission rate from the East Siberian Arctic shelf area based on the statistics of a very large number of observed bubble seeps.

Is the methane flux from the Arctic accelerating?

Shakhova et al (2013) argue that bottom water temperatures are increasing more than had been recognized, in particular in near-coastal (shallow) waters. Sea ice cover has certainly been decreasing. These factors will no doubt lead to an increase in methane flux to the atmosphere, but the question is how strong this increase will be and how fast. I’m not aware of any direct observation of methane emission increase itself. The intensity of this response is pretty much the issue of the dispute about the Arctic methane bomb (below).

What about the extremely high methane concentrations measured in Arctic airmasses?

Shakhova et al (2013) show shipboard measurements of methane concentrations in the air above the ESAS that are almost twice as high as the global average (which is already twice as high as preindustrial). Aircraft measurements published last year also showed plumes of high methane concentration over the Arctic ocean (Kort et al 2012), especially in the surface boundary layer. It’s not easy to interpret boundary-layer methane concentrations quantitatively, however, because the concentration in that layer depends on the thickness of the boundary layer and how isolated it is from the air above it. Certainly high methane concentrations indicate emission fluxes, but it’s not straightforward to know how significant that flux is in the global budget.

What about methane hydrates?

There are three possible sources of the methane in the bubbles rising out of the Siberian margin continental shelf:

  1. Decomposition (fermentation) of thawing organic carbon deposited with loess (windblown glacial flour) when the sediment was exposed to the atmosphere by low sea level during the last glacial time. Organic carbon deposits (called Yedoma) are the best-documented carbon reservoir in play in the Arctic.
  2. Methane gas that has been trapped by ice, now escaping. Shakhova et al (2013) figure that flaws in the permafrost called taliks, resulting from geologic faults or long-running rivers, might allow gas to escape through what would otherwise be impermeable ice. If there were a gas pocket of 50 Gt, it could conceivably escape quickly as a seal breached, but given that global gas reserves come to ~250 Gt, a 50 Gt gas bubble near the surface would be very large and obvious. There could be 50 Gt of small, disseminated bubbles distributed throughout the sediment column of the ESAS, but in that case I’m not sure where the short time scale for getting the gas to move comes from. I would think the gas would dribble out over the millennia as the permafrost melts.
  3. Decomposition (melting) of methane hydrates, a peculiar form of water ice cages that form in the presence of, and trap, methane.

Methane hydrate seems menacing as a source of gas that can spring aggressively from the solid phase like pop rocks (carbonated candies). But hydrate doesn’t just explode as soon as it crosses a temperature boundary. It takes heat to convert hydrate into fluid + gas, what is called latent heat, just like regular water ice. There could be a lot of hydrate in Arctic sediments (it’s not real well known how much there is), but there is also lot of carbon as organic matter frozen in the permafrost. Their time scales for mobilization are not really all that different, so I personally don’t see hydrates as scarier than frozen organic matter. I think it just seems scarier.

The other thing about hydrate is that at any given temperature, a minimum pressure is required for hydrate to be stable. If there is pure gas phase present, the dissolved methane concentration in the pore water, from Henry’s law, scales with pressure. At 0 degrees C, you need a pressure equivalent to ~250 meters of water depth to get enough dissolved methane for hydrate to form.

The scariest parts of the Siberian margin are the shallow parts, because this is where methane bubbles from the sea floor might reach the surface, and this is where the warming trend is observed most strongly. But methane hydrate can only form hundreds of meters below the sea floor in that setting, so thermodynamically, hydrate is not expected to be found at or near the sea floor. (Methane hydrate can be found close to the sediment surface in deeper water depth settings, as for example in the Gulf of Mexico or the Nankai trough). The implication is that it will take centuries or longer before heat diffusion through that sediment column can reach and destabilize methane hydrates.

More at RealClimate.

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34 Responses to “Methane Bomb Squad Part 5: Shakhova, Schmidt”


  1. Its valid to question why we did not see evidence of a methane spike in the geologic record even though temperatures were higher than todays. There is no conclusive evidence as yet, and the field is still making discoveries. Thats not a good time to be making projections. The answer is simply, we have no evidence to conclude that a runaway greenhouse is likely. We cannot say yes or no. We can say it bears careful consideration, monitoring, and further research. Here is a reference to Skeptical Science on the subject, for this with a taste for research.
    http://www.skepticalscience.com/toward-improved-discussions-methane.html

    • jimbills Says:

      Reposting the Ahmed article referred by redskylite. Please read:
      http://www.theguardian.com/environment/earth-insight/2013/aug/05/7-facts-need-to-know-arctic-methane-time-bomb

      I think a big reason why some are upset about this issue isn’t so much that they’re certain we’ll have a catastrophic release in a few decades (although some do think that). It’s that there seems to be a rush to dismiss or downplay those concerns, and in doing so ignoring the fact that we don’t know the issue for certain and employing much of the same language the deniers do when discussing it.

      One can say it’s wrong to claim certainty on a subject that is uncertain, but in doing so one can’t claim certainty themselves.

      The Skeptical Science article concludes, “There is no evidence that methane will run out of control and initiate any sudden, catastrophic effects.” That strongly implies certainty to me. Is that certainty justifiable?

      Additionally, I don’t see a big difference between timescales of a decades and timescales of centuries, and most of the research indicates the odds of catastrophic releases increase with added time. We just put weight on the short-term timeframe because we think we matter. We don’t, other than how we choose to react to the science, and the science suggests it’ll more likely happen later than sooner, but there’s a chance of it happening. And as it’s been pointed out, we thought the same about a number of other things once, too, like Arctic ice melt.

    • dumboldguy Says:

      Arcus appears again with a link to an article that he has not read or does not understand. Or perhaps he is just doing his “Mr. Bright-Sided thing” and refusing to acknowledge what the article concludes. It won’t go away, just as I won’t because Arcus refuses to answer my criticisms of his posts. He again seeks CONCLUSIVE evidence, and is hypocritical enough to say “Thats not a good time to be making projections” when he relies on PROJECTIONS for all of his arguments on grid, storage, solar, and renewables.

      Actually, it is probably more truthful to say “we have no evidence to conclude that a runaway greenhouse is definitely NOT likely”, and “We can say it bears careful consideration, monitoring, and further research” is what I say to myself when I notice some strange-looking new growth on my aging epidermis.

      For those with a taste for REALLY ANALYZING research, here are some direct quotes from the CONCLUSION of the cited Skeptical Science piece.

      “To be clear, CH4 is important as we go forward, and is already a key climate forcing agent behind CO2 (coming in at ~0.5 W/m2 radiative forcing since pre-industrial times). Additionally, methane is quite reactive in the atmosphere, and the effect of other things like tropospheric ozone, aerosols, or stratospheric water vapor are partly slaved to whatever is happening to methane (Shindell et al., 2009). This means methane emitted has a bigger collective impact on climate than if you just do the radiative forcing calculation by comparing methane concentration changes to what it was in 1750”.

      “Permafrost thawing is also going to be important in the coming century (this is a good paper), and the uncertainties pretty much go one way on this. There’s not much wiggle room to argue that permafrost will reduce CH4/CO2 concentrations in the future. This is also likely to be a sustained release rather than one big catastrophic event. For example, permafrost was not included in Lenton (2008) as a “tipping point” for precisely the reason that there’s no evidence for any “switch” of rapid behavior change. Much of the carbon is also likely to be in the form of CO2 to the atmosphere, and even implausible thought experiments of catastrophic methane release (see David Archer’s post at RealClimate) give you comparable results in the short-term as to what CO2 is going to do for a long time.

      Conclusion

      “The observed methane venting from the East Siberian shelf sea-floor to the atmosphere is probably not a new component of the Arctic methane budget. Furthermore, warming of the Arctic waters and sea ice decline will likely impact subsea permafrost on longer timescales, rather than the short term.

      “Methane feedbacks in the Arctic are going to be important for future climate change, just like the direct emissions from humans. This includes substantial regions of shallow permafrost in the Arctic, which is already undergoing appreciable change. Much larger changes involving hydrate may be important longer-term. Nonetheless, these feedbacks need to be kept in context and should be thought of as one of the many other carbon cycle feedbacks, and dynamic responses, that supplement the increasing anthropogenic CO2 burden to the atmosphere. There is no evidence that methane will run out of control and initiate any sudden, catastrophic effects. There’s certainly no runaway greenhouse. Instead, chronic methane releases will supplement the primary role of CO2. Eventually some of this methane oxidizes into CO2, so if the injection is large enough, it can add extra CO2 forcing onto the very long term evolution of global climate, over hundreds to thousands of years.

      Note the many inclusions of qualifying terms like “likely”, “going to be important”, “probably”, etc., and the kicker of “the very long term evolution of global climate, over hundreds to thousands of years”. The bright-sided among us insist on gleefully kicking the can down the road when they see that kind of statement. The realists among us say “hundreds to thousands of years” is an eye-blink in the history of the earth, and look at all the present evidence that says “not if, but when”. McPherson may be jumping the gun time-wise with 2030, just as Ehrlich did with Population Bomb, but their conclusions are NOT invalid.


      • Jimbills – read the comments section that echos the concerns and views expressed here. For the record, as far as sudden catastrophic methane release goes, I dont know. The scientists don’t seem to be of one opinion, and new details emerge. Some of the comments pointed to the PETM as a possible example. I recall flood basalts from the Siberian traps as a favored culprit. The PT extinction is pertinent. The mechanisms are not clear. Could the pyro clastic flow have acted to release methane or were the volcanic gases the culprit? The questions are so unsettled that some scientists still point to impact events as the cause. There certainly were major deadly atmospheric changes. We should find out. It’s certain that carbon dioxide will be a major threat. Methanes potential for disaster is huge. No one knows with certainty yet. Even if catastrophic methane appears unlikely, that’s no reason not to avoid it. We already have plenty of reasons to stop GW. We don’t know means we must find out. Discussion here , where many lack the background, will not settle the scientific matter. The posts at Skeptical Science are often by scientists in those particular fields. I don’t like to jump from not knowing to conjecture. It really doesn’t help. On the one hand, dismissing it could be dangerous, on the other, over reacting could stifle research and understanding. scientists must resist the urge to come to conclusions where none are warranted. I expect there to be a warm debate in scientific circles.

        • dumboldguy Says:

          Hmmmmm—-Arcus replies to a comment by DOG by appealing to Jimbills???? Or did he just “reply” in the wrong place and is again thinking I will go away and not point our his failures of fact and logic?

          I fear that he has shown us yet another area that he needs to bone up on a bit before making confusing comments on Crock—-volcanism.

          The gas released in volcanic eruptions is mostly water vapor, with CO2 making up most of the rest, followed by sulfur compounds—-methane is way down the list. Flood basalts are not explosive and typically do not show much evidence of pyroclastic flows—-the lava comes out of fissures in sheets and “floods” large areas and again, the gasses released contain little methane. The Siberian Traps were created 250 million years ago, and that’s “ancient history”. We don’t fully understand the PETM either, but it is much more relevant to what we face today.

          Arcus DOES say something I can agree with wholeheartedly. “I don’t like to jump from not knowing to conjecture. It really doesn’t help”. He should heed his own advice.

  2. redskylite Says:

    I see that Dr Shakhova has written a well mannered letter to the Royal Society, and agree that out of respect to over 20 years of research in the Arctic Dr. Natalia Shakhova, and her associate Dr. Igor Semilitov would have been ideal to talk on their specialist subject.

    October 4th, 2014
    By mail and email

    Dear Sir Paul Nurse,

    We are pleased that the Royal Society recognizes the value of Arctic science and hosted an important scientific meeting last week, organized by Dr D. Feltham, Dr S. Bacon, Dr M. Brandon, and Professor Emeritus J. Hunt (https://royalsociety.org/events/2014/arctic-sea-ice/

    ).

    Our colleagues and we have been studying the East Siberian Arctic Shelf (ESAS) for more than 20 years and have detailed observational knowledge of changes occurring in this region, as documented by publications in leading journals such as Science, Nature, and Nature Geosciences. During these years, we performed more than 20 all-seasonal expeditions that allowed us to accumulate a large and comprehensive data set consisting of hydrological, biogeochemical, and geophysical data and providing a quality of coverage that is hard to achieve, even in more accessible areas of the World Ocean.

    To date, we are the only scientists to have long-term observational data on methane in the ESAS. Despite peculiarities in regulation that limit access of foreign scientists to the Russian Exclusive Economic Zone, where the ESAS is located, over the years we have welcomed scientists from Sweden, the USA, The Netherlands, the UK, and other countries to work alongside us. A large international expedition performed in 2008 (ISSS-2008) was recognized as the best biogeochemical study of the IPY (2007-2008). The knowledge and experience we accumulated throughout these years of work laid the basis for an extensive Russian-Swedish expedition onboard I/B ODEN (SWERUS-3) that allowed more than 80 scientists from all over the world to collect more data from this unique area. The expedition was successfully concluded just a few days ago.

    To our dismay, we were not invited to present our data at the Royal Society meeting. Furthermore, this week we discovered, via a twitter Storify summary (circulated by Dr. Brandon), that Dr. G. Schmidt was instead invited to discuss the methane issue and explicitly attacked our work using the model of another scholar, whose modelling effort is based on theoretical, untested assumptions having nothing to do with observations in the ESAS. While Dr. Schmidt has expertise in climate modelling, he is an expert neither on methane, nor on this region of the Arctic. Both scientists therefore have no observational knowledge on methane and associated processes in this area. Let us recall that your motto “Nullus in verba” was chosen by the founders of the Royal Society to express their resistance to the domination of authority; the principle so expressed requires all claims to be supported by facts that have been established by experiment. In our opinion, not only the words but also the actions of the organizers deliberately betrayed the principles of the Royal Society as expressed by the words “Nullus in verba.”

    In addition, we would like to highlight the Anglo-American bias in the speaker list. It is worrisome that Russian scientific knowledge was missing, and therefore marginalized, despite a long history of outstanding Russian contributions to Arctic science. Being Russian scientists, we believe that prejudice against Russian science is currently growing due to political disagreements with the actions of the Russian government. This restricts our access to international scientific journals, which have become exceptionally demanding when it comes to publication of our work compared to the work of others on similar topics. We realize that the results of our work may interfere with the crucial interests of some powerful agencies and institutions; however, we believe that it was not the intent of the Royal Society to allow political considerations to override scientific integrity.

    We understand that there can be scientific debate on this crucial topic as it relates to climate. However, it is biased to present only one side of the debate, the side based on theoretical assumptions and modelling. In our opinion, it was unfair to prevent us from presenting our more-than-decadal data, given that more than 200 scientists were invited to participate in debates. Furthermore, we are concerned that the Royal Society proceedings from this scientific meeting will be unbalanced to an unacceptable degree (which is what has happened on social media).

    Consequently, we formally request the equal opportunity to present our data before you and other participants of this Royal Society meeting on the Arctic and that you as organizers refrain from producing any official proceedings before we are allowed to speak.

    Sincerely,
    On behalf of more than 30 scientists,
    Natalia Shakhova and Igor Semiletov


  3. I am agog and flummoxed.

    I sincerely respect Dr. Schmidt. However, I cannot abide the shortsightedness of his interpretation of the paleo data.

    1. Claim: No Holocene emissions.
    1. rebuttal: The inundation of the ESAS had only recently occurred. Of course there would be no signal, it would not be expected. The decomposition depth profile had not reached adequate depth. How can one miss this obvious modelling error?

    2. Claim: No Eemian peak CH4 spike (above Holocene)
    2. rebuttal: Of course there would be no spike in the ice core data, the CH4 signal is smoothed over 400 years in the record. In addition, claiming analogous warming profiles in the Eemian to RCP 8.5 is not technically accurate. While the Eemian was warmer than today, it likely took thousands of years to reach that warmer state from current temperatures. We would then expect a slower release mechanism. This slower release would fail to produce a significant spike in the ice-core data due to the smoothing of the signal described above and due to atmospheric decomposition.

    Summary: claiming that there is an analog in the 800Ka ice core record to the RCP 8.5 potential warming event is absolutely not technically accurate. Not including the effects of time-dependent heat/depth profiles and slower warming rates in the paleo record is poor science. Claiming that this somehow insulates us for the technical potential of an ESAS release under RCP 8.5 after an unprecedented (over the past 3.5 million years) jump in arctic temperatures is foolhardy, shortsighted and rash.


  4. Peter —

    If Gavin’s best defense is the Eemian, which Hansen suggests we’re already hotter than, then we may have more reason to be concerned than your article suggests.

    It’s also worth noting that Gavin did not have the opportunity to debate Shakhova, primarily due to the RS failure to invite her.

  5. indy222 Says:

    I’ve got a quantitative question – CH4 levels were fairly stable in the late 20th century, but took a sharp turn to a linear rise all during the 21st century so far. Question – can this plausibly be attributed to Arctic methane? David (Archer?) in Realclimate.org argues that methane primarily comes from the tropics, and the Arctic is a minor player. But I can’t find any actual numbers to this. Ballpark back-of-envelope might help us guess whether this is from leaks from the natural gas mining boom, or flooded lakes in the tropics from dam building, or the Arctic. This is a very important question.
    If anyone has come across a good discussion of this, beyond Archer’s in Realclimate, I’d love to see it.


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