Tuesday, December 27, 2011

Semiletov and Shakhova report



The methane researchers who disturbed our rest and inspired immediate, pre-communication debunking by Andrew Revkin, Semiletov and Shakhova, now explain their concerns to him based on the recent findings:
We would first note that we have never stated that the reason for the currently observed methane emissions were due to recent climate change. In fact, we explained in detail the mechanism of subsea permafrost destabilization as a result of inundation with seawater thousands of years ago. We have been working in this scientific field and this region for a decade. We understand its complexity more than anyone.  And like most scientists in our field, we have to deal with slowly improving understanding of ongoing processes that often incorporates different points of views expressed by different groups of researchers.
Yes, modeling is important. However, we know that modeling results cannot prove or disprove real observations because modeling always assumes significant simplification and should be validated with observational data, not vice versa. Much of our work includes this field validation. Last spring, we extracted a 53-meter long core sample from the East Siberian Arctic Shelf, to validate our conclusions about the current state of subsea permafrost. We found that the temperatures of the sediments were from 1.2 to 0.6 degrees below zero, Celsius, yet they were completely thawed. The model in the Dmitrenko paper [link] assumed a thaw point of zero degrees. Our observations show that the cornerstone assumption taken in their modeling was wrong. The rate at which the subsea permafrost is currently degrading largely depends on what state it was in when recent climate change appeared. It makes sense that modeling on an incorrect assumption about thaw point could create inaccurate results.
Observations are at the core of our work now. It is no surprise to us that others monitoring global methane have not found a signal from the Siberian Arctic or increase in global emissions. [This refers to the work of Ed Dlugokencky and others; see his comments in my Dot Earth post.] The number of stations monitoring atmospheric methane concentrations worldwide is very few. In the Arctic there are only three such stations — Barrow, Alert, Zeppelin — and all are far away from the Siberian Arctic. We are doing our multi-year observations, including year-round monitoring, in proximity to the source. In addition to measuring the amount of methane emitted from the area, we are trying to find out whether there is anything specific about those emissions that could distinguish them from other sources. It is incorrect to say that anyone is able to trace that signal yet.
All models must be validated by observations. New data obtained in our 2011 cruise and other unpublished data give us a clue to reevaluate if the scale of methane releases from the East Siberian Arctic Shelf seabed is assessed correctly (papers are now in preparation). This is how science works: step by step, from hypothesis based on limited data and logic to expanded observations in order to gain more facts that could equally prove or disprove the hypothesis. We would urge people to consider this process, not jump to conclusions and be open to the idea that new observations may significantly change what we understand about our world.
So what is the news here? The different thaw point result will need to be replicated. How far down the melt goes should be directly measured in as many locations as possible. Meanwhile, it should be trivial to do model runs at different thaw points and see what effect that might have.

10 comments:

  1. So OK, they got really clear marching orders to STFU until the pubs come out, other than the AGU poster. Interesting. Possibly Joye and Leifer, who were under intense media scrutiny just recently due to their leading role in gathering evidence on the Gulf BP spill, gave them a talking to.

    Just to note, although this may be redundant, the obs of expanding methane bubbling reported in the poster are not the same thing as evidence of atmospheric emissions. Most of that methane could be dissolving and getting eaten by microbes, although even if it is that leaves open the question of whether that will continue to be the case in the future. We shall see soon enough, apparently.

    You note that the core results should be replicated, which is fair enough, but a slightly more salient issue may be whether the model used by Dmitrenko et al. simply assumed the melting temperature (albeit from a calculation based on physical parameters) or based it directly on data.

    Elsewhere in the climate news, yet another cryosphere modeling projection bites the dust.

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  2. Steve, I would ask you why you don't have your own blog, but after dragging this one around like Marley's chain for the last year and a half, I have a very clear idea why a smart person might chose to abstain.

    If you ever have the desire to sound off above the fold, I'd be delighted to have you as a guest poster.

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  3. As chair of the Arctic Methane Emergency Group [1], I have spoken to both researchers Igor Semiletov and Natalia Shakhova at the AGU meeting, and have posted comment on Andy Revkin's articles. I would like to explain why our group considers the situation in the Arctic as a planetary emergency.

    There have been two major factors that have been drawn to our attention this year: (1) the astonishing decline in sea ice volume, as shown by the PIOMAS model [2] and trend curve drawn here [3]; and (2) the precarious state of methane-holding structures in the Arctic Ocean.

    The PIOMAS model, and the trend curve deduced from it, is supported by Prof Peter Wadhams, a leading expert on Arctic sea ice. The sea ice extent has been holding up since the remarkable record minimum in September 2007, but the ice has been steadily thinning, largely melting from below as the currents and rivers flowing into the Arctic have warmed. The thinning cannot continue without a collapse in extent, and this, according to the current trend, is most likely in summer 2014 or 2015 (about equally the most likely). According to this trend, there's a >5% chance of collapse in summer 2013.

    The only way to prevent a possible collapse so soon is by geoengineering to cool the Arctic. In theory the necessary cooling power can be produced by either of two techniques: reflecting aerosols (as produced by coal power stations and large volcanic eruptions) and cloud brightening.

    However, after the sea ice has collapsed in extent during one summer, so there is little ice left, it might prove impossible to subsequently cool the Arctic and reverse the retreat, however much geoengineering was attempted. Effectively such a collapse would be a point of no return.

    The implications of passing this point of no return would be that the Arctic would continue warming, and at a much faster rate. This would provide conditions for methane feedback, where methane would, through its initial warming effect (over 100 times that of CO2, weight for weight), warm the Arctic such as to release more methane, in what is known as a positive feedback loop.

    One of the observations of Igor Semiletov is that the retreat of sea ice from the East Siberian Arctic Shelf (ESAS) has been an increase in storms and the churning of water to reach the seabed. Thus we have conditions for methane feedback to start.

    But if the Arctic is to continue warming, we could be getting methane feedback not only from ESAS, but from methane hydrates on shelf margins and from thawing terrestrial permafrost (where there is a vast amount of carbon locked up). This faster speed of Arctic warming, coupled with the absence of sea ice cover, would make methane feedback almost inevitable.

    Thus it is the significant possibility of passing a point of no return in the summer of 2013 which drives the conclusion of the Arctic Methane Emergency Group that we have a planetary emergency and to call for large-scale deployment of geoengineering techniques (preferably several in conjunction) by spring 2013.

    Kind regards,

    John Nissen
    Chair: Arctic Methane Emergency Group

    [1] www.arctic-methane-emergency-group.org

    [2] http://neven1.typepad.com/blog/2011/10/piomas-september-2011-volume-record-lower-still.html

    [3] http://neven1.typepad.com/.a/6a0133f03a1e37970b0153920ddd12970b-pi

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  4. "However, after the sea ice has collapsed in extent during one summer, so there is little ice left, it might prove impossible to subsequently cool the Arctic and reverse the retreat, however much geoengineering was attempted. Effectively such a collapse would be a point of no return."

    Hmmm. Isn't there modelling that suggests that a sudden collapse in ice volume/extent would be quickly followed by a return to the baseline (which is, of course, a rapid decline?) Let me see if I can find the link . . .

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  5. Those studies basically took away all the ice and looked at what would happen under current conditions. It returned, of course, but at the least it seems that the loss isn't self-persistent. However, the actual situation we're faced with is quite different, i.e. a loss as a consequence of warming with the latter trend continuing. Very likely natural variabilty will be sufficient to result in some subsequent years that aren't ice-free (noting that this doesn't mean entirely ice-free, but rather below some minimum that accounts for the persistence of ice in sheltered spots along the coast), but those won't be much of a comfort since they'll occur even as the ice-free period lengthens on average.

    I'll have to think about whether the concept of emergency geoengineering scares me more than AGW itself. Maybe.

    A related thought I've had is that the idea of the first ice-free summer period has been talked about so much that it really won't have much of an impact when it finally happens. Those unprojected consequences that we've started to see may be doing us a big favor.

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  6. Tracker,

    I know it's a bit late but I'm reading up on CH4 and stumbled on this post.

    The study you're probably thinking of is Tietsche et al, they find that removal of sea-ice even in future conditions is followed by recovery of sea-ice due to loss of IR and latent heat into the atmosphere from the ocean.

    Abbot et al 2011 consider this to be an issue with the model Tietsche et al use stating that the model appears to have no hysteresis. In the context of the Abbot et al paper this may be due to model parameters, Abbot et al find that differences between models is due to different parameters.

    Meanwhile back in the real world it's not known what the real parameters are. So it's hard to say how fast the transition to seasonally sea-ice free, and thence to perennially ice free, will be.

    I'm currently in the middle of Eisenman 2011 "Factors controlling the bifurcation structure of sea ice retreat." I haven't changed my opinion that we won't see a rapid transition to seasonally sea-ice free this decade.

    Abbot et al, 2011, Bifurcations leading to summer Arctic sea ice loss.

    Tietsche et al, 2011, Recovery mechanisms of Arctic summer sea ice.

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  7. Thanks Chris.

    I brought up the Pilocene in a discussion with Judith Curry -- i.e., doesn't a recent historical period with an identical CO2 burden and no Arctic sea ice seem to imply a tipping point somewhere?

    She thought the difference was down to geography, leading to different ocean currents and ice export. I went looking for a world map of the Pilocene (surprisingly hard to find!) and it looks pretty similar to me.

    So I am actively confused as to what to expect. I'll check out those links. Your prediction for the coming decade is noted. Want to be bold and imagine the Arctic in 2050?

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  8. Well, hey, nobody found the tropical iris, why not postulate a polar ... um, block that metaphor.

    A polar cooling mechanism, that's it.

    Do the ideas for possible recovery of sea ice factor in the colder stratosphere that's making the arctic ozone hole worse?

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  9. You got confused talking to Judith Curry? Really?

    Ha Ha Ha Ha Ha

    No surprise there. ;)

    My prediction for this decade? Would that be my post about not expecting a rapid transition this decade? Made me rather unpopular with quite a few people that one did.

    Arctic in 2050? I suspect perennially sea-ice free with clathrates and permafrost stoking up what Archer terms a chronic release of CH4, but not a catastrophic one. That's just what I suspect, not a firm prediction, and I'm reading up on Arctic CH4 right now so could end up siding with the catastrophic camp on that. I did change sides on the drought driven catastrophe as you've seen.

    I've come across denialists who see changing stance as a weakness - says so much about them.

    Hank,
    You saw it in The Day After Tomorrow - frigid upper atmospheric air descending to plunge us into a new ice age. Works OK as long as you forget Charles' Law.

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