A methane scoping question

September 23, 2008 at 11:51 am | Posted in Climate change, Environment, Global warming | 5 Comments
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Can any climate scientist knowledgable on the significance of Arctic sub-sea methane release put today’s Independent Front Page ‘Exclusive: The methane time bomb‘ into context for me, please?  It is a perspective on the scale of today’s news that would be good to have.  Just because the intensity of release in certain areas is high and millions of tonnes of methane are being released, does not mean that this is as significant as implied by the article, nor that such releases have not already been catered for in model scenarios.  Although, when I read on RealClimate Ray Ladbury’s comment dated 18 May 2008:

There is evidence for positive feedback that is not in the models (e.g. outgassing from thawing permafrost, oceans, etc.)

it makes me wonder how to begin to quantify today’s news (while acknowledging this information has been released in mainstream media before preliminary findings are published in AGU literature).

Here are a couple of quotes:

Orjan Gustafsson of Stockholm University in Sweden, one of the leaders of the expedition, described the scale of the methane emissions in an email exchange sent from the Russian research ship Jacob Smirnitskyi.

“We had a hectic finishing of the sampling programme yesterday and this past night,” said Dr Gustafsson. “An extensive area of intense methane release was found. At earlier sites we had found elevated levels of dissolved methane. Yesterday, for the first time, we documented a field where the release was so intense that the methane did not have time to dissolve into the seawater but was rising as methane bubbles to the sea surface. These ‘methane chimneys’ were documented on echo sounder and with seismic [instruments].”

and

The preliminary findings of the International Siberian Shelf Study 2008, being prepared for publication by the American Geophysical Union, are being overseen by Igor Semiletov of the Far-Eastern branch of the Russian Academy of Sciences. Since 1994, he has led about 10 expeditions in the Laptev Sea but during the 1990s he did not detect any elevated levels of methane. However, since 2003 he reported a rising number of methane “hotspots”, which have now been confirmed using more sensitive instruments on board the Jacob Smirnitskyi.

Steve Connor did a parallel backgrounder here:

Steve Connor: The ultimate gas leak that scientists dreaded

Although I don’t like the use of ‘ultimate’—as it implies finality—nor am I keen on the überscary word ‘dreaded’ in the title, I accept, with a sigh, that headlines are written to grab attention in the hope that some people read beyond … 

Anyway, methane emissions are hardly on the radar screens of most policymakers or businessmen, as far as I am aware.  There is not a lot they can do about it, but with headline stories like this, if methane has the potential to wreak havoc on a large scale, and significant climate change seems inevitable, people will perhaps ask “Why bother trying to reduce carbon emissions?”  Context would help … ;-)

If radiative forcing is used to measure climate impacts of GHGs, the total methane contribution to warming to date appears to be less lethal compared with the total contribution from carbon dioxide, which accounts for three times the warming so far.  According to wiki, methane concentrations have increased 150% since industrial revolution, giving an RF of +0.48 W/m2, while carbon dioxide concentrations have increased 38% to give RF of +1.46 W/m2.

Steve Connor is underestimating the power of methane when he says it is about 20 times more potent than carbon dioxide as a greenhouse gas: it has a century-timescale global warming potential (GWP) of 23, but the relevant figure for its potency in the first 20 years after its release is 62, dropping to 23 over 100 years, and 7 over 500 years.

Some of that CH4 gets converted to CO2 along the way, but the point is that for the same mass of gas, methane packs 62 times the punch of carbon dioxide in the first two decades after its release into the atmosphere.  This is obviously not good if we consider targets for reducing CO2 emissions by 2020, 2030 or even all the way to 2050, as methane has the ability to increase the greenhouse effect dramatically sooner and add to the long-lasting carbon dioxide concentrations later.

I just wonder how climate scientists would frame an answer to members of the public who noticed the front page methane story in today’s Independent newspaper and who want to, somehow, gauge its significance.

P.S.  Two days later, and Steve Connor has another story about methane bubbles from the Arctic seabed, this time discovered by British research scientists near the Norwegian island, Svalbard:

Hundreds of methane ‘plumes’ discovered

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5 Comments »

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  1. As of this moment this isn’t in the models in a broad sense (and shouldn’t be since there’s no basis for predicting a major release in the coming century, although the new obs may change that thinking).
    .
    Here’s some background on the big risk. It doesn’t seem possible to trigger something like this with just the ESS clathrates, but many references will get made to it as the current story unfolds. (I like to use this link to respond to denialists who raise the “it’s been warmer due to natural variability” argument. Indeed it has.)
    .
    Interestingly there was an excellent Spiegel article (it and other info linked and discussed in this Hot Topic post) last spring that surprisingly resulted in absolutely nothing in the rest of the media.
    .
    As far as I can see, the immediate concern is that the same warming currents that seem to be the key added factor behind the sea ice loss may be capable of inducing a relatively quick melt of the clathrates. Bear in mind that the clathrates have survived prior deglacials, but then those currents (which come from the south) may not have been present then. I don’t know if anyone even knows the answer to that.
    .
    Anyway, Andy Revkin has the story now, so watch his blog for something soon.

  2. AR4 gives methane GWP as 72/20yrs, 25/100 years. So a bit worse… (See my comment at Stoat for more, and check the methane tag at my place for earlier refs).

  3. Thank you so much, Steve, for the background in Geoscientist and the Hot Topic post linking to the Spiegel article. I appreciate you treating my enquiry with respect, rather than dismissing it as an attempt at alarmism (which my post is not, but others seem to think so).
    .
    The approach to methane bubbles that Andy Revkin is taking sounds reasonable and helpful, and I will keep an eye on his Dot Earth blog.

  4. Hello Gareth, I just read From Russia, with love and am grateful for your input.
    .
    The Independent story was flagged to me by several friends, and it was front page exclusive headline so was designed to catch the eye of people in Britain. I drew attention to it because members of the public do not know how to gauge such news when it hits them in the face.
    .
    It seems to me an appropriate response to ‘responsible public wonderings’ ought to be more considered than dismissive. Unfortunately, some stories are immediately shrugged off as ‘sceptic drivel’ and others rejected as ‘alarmist twaddle’, when they do offer an opportunity for scientists to set the scene for mere mortals. Although I’m a firm advocate of not believing all we read, there is usually a driver behind the publication of articles, even if the trigger for news is not clear, and its significance is hard to justify, to readers.
    .
    P.S. Thanks for updating the 2001 TAR GWP figures I used (62-23-7) to 2007 AR4 GWP ones (72-25-7.6). That will teach me to pick a quiki from wiki before running to catch the train to Oxford, instead of referring to IPCC AR4 ;-)

  5. P.S. Two days later, and Steve Connor has another story about methane bubbles from the Arctic seabed, this time discovered by British research scientists near the Norwegian island, Svalbard:
    Hundreds of methane ‘plumes’ discovered
    .

    “The discovery of this system is important as its presence provides evidence that methane, which is a greenhouse gas, has been released in this climactically sensitive region since the last ice age,” Professor Westbrook said. …

    “We were very excited when we found these plumes because it was the first evidence there was an active gas system in this part of the world,” Professor Westbrook said after disembarking from the ship, which arrived back in Britain yesterday. “Now we know it’s there we know we have to very seriously consider its effect.”


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