Nature puts methane hydrate fears to rest – says it will be 1,000 years before they make any impact

Ruppel Banner

As the evidence for warming climate became better established in the latter part of the 20th century (IPCC 2001), some scientists raised the alarm that large quantities of methane (CH4) might be liberated by widespread destabilization of climate-sensitive gas hydrate deposits trapped in marine and permafrost-associated sediments (Bohannon 2008, Krey et al. 2009, Mascarelli 2009). Even if only a fraction of the liberated CH4 were to reach the atmosphere, the potency of CH4 as a greenhouse gas (GHG) and the persistence of its oxidative product (CO2) heightened concerns that gas hydrate dissociation could represent a slow tipping point (Archer et al. 2009) for Earth’s contemporary period of climate change.

WUWT reader “Jos” advises in Tips and Notes of this essay in Nature’s Knowledge Project. Excerpts follow:

Methane Hydrates and Contemporary Climate Change

Concern about the long-term stability of global gas hydrate deposits is rooted in the potential impact that a large CH4 release might have on global climate. CH4 is ~20 times more potent than CO2 as a GHG, but it oxidizes to CO2 after about a decade in the atmosphere. In recent models, the longer-lived CO2 oxidation product (Archer et al. 2009), not the CH4 itself (e.g., Harvey & Huang 1992), is credited with causing most of the excess atmospheric warming that would follow large-scale dissociation of methane hydrates.

The present-day concentration of CH4 in the atmosphere is ~200 times lower than that of CO2, but CH4 concentrations have risen by ~150% since pre-industrial times, compared to only ~40% for CO2 (IPCC 2001). Rising atmospheric CH4 concentrations lead to more rapid depletion of the hydroxyl radicals needed for oxidation, longer CH4 residence times, and thus increased CH4-induced warming (Lelieveld et al. 1998). Present-day CH4 emissions are dominated by wetlands, ruminants, fossil fuel production, and rice cultivation (IPCC 2001), sources that fluctuate with season, human behavior, and other factors. The IPCC (2001, 2007) relies on estimates and models (Fung et al. 1991, Lelieveld et al. 1998, Wang et al. 2004) to attribute ~3.75×10-4 Gt C (IPCC 2001), or ~1% of annual global CH4 emissions, to dissociating gas hydrates. This estimate has never been validated, nor do any observational data unequivocally link specific CH4 emissions or regionally integrated CH4 fluxes to dissociating gas hydrates. Against the backdrop of a well-mixed atmosphere, strong annual fluctuations, and a significant increase in CH4 concentrations over the 20th century, detecting a CH4 signal that is directly attributable to dissociating gas hydrates may always remain challenging.

Gas Hydrates and Past Warming Events

The geologic record is punctuated by warming events that may provide clues about future interactions between methane hydrates and climate change. The Paleocene-Eocene Thermal Maximum (PETM) at ~54.95 Ma is the most intensely studied of these hyperthermals (e.g., Dickens et al. 1995, Schmidt & Shindell 2003, Renssen et al. 2004, Zachos et al. 2001, 2005, Röhl et al. 2007). The large, negative carbon isotopic excursion (CIE) recorded in both marine and terrestrial sediments during the PETM has been interpreted as reflecting widespread release of isotopically-light (microbial) carbon from dissociating marine methane hydrates (e.g., Dickens et al. 1995, Zachos et al. 2005). This explanation is also invoked to explain CIEs in other deep-time warm periods (Hesselbo et al. 2000, Jiang et al. 2003). Negative CIEs also undergird the clathrate gun hypothesis (CGH), which postulates that repeated warming of intermediate ocean waters during the Late Quaternary (since 400 ka) triggered periodic dissociation events (Kennett et al. 2003).Ice core data (Sowers 2006) and geologic studies (Maslin et al. 2003) have challenged the CGH, while Bock et al. (2010) and Petrenko et al. (2009) question the role of gas hydrate dissociation in contributing to increased atmospheric CH4 during more recent warming events as well. Northern hemisphere wetlands, which may experience increased production of isotopically-light CH4 in response to local warming, appear to be the key culprit in enhancing atmospheric CH4 concentrations during several Pleistocene (~2.6 Ma to 10 ka) and Holocene (since 10 ka) warming events.

Conclusions:

Catastrophic, widespread dissociation of methane gas hydrates will not be triggered by continued climate warming at contemporary rates (0.2ºC per decade; IPCC 2007) over timescales of a few hundred years. Most of Earth’s gas hydrates occur at low saturations and in sediments at such great depths below the seafloor or onshore permafrost that they will barely be affected by warming over even 10^3 yr. Even when CH4 is liberated from gas hydrates, oxidative and physical processes may greatly reduce the amount that reaches the atmosphere as CH4. The CO2 produced by oxidation of CH4 released from dissociating gas hydrates will likely have a greater impact on the Earth system (e.g., on ocean chemistry and atmospheric CO2 concentrations; Archer et al. 2009) than will the CH4 that remains after passing through various sinks.

Ruppel, C. D. (2011) Methane Hydrates and Contemporary Climate Change. Nature Education Knowledge 3(10):29

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

About these ads

27 thoughts on “Nature puts methane hydrate fears to rest – says it will be 1,000 years before they make any impact

  1. Donning my grammarian stickler’s hat I point out that “The present-day concentration of CH4 in the atmosphere is ~200 times lower than that of CO2″ is impossible (though the equivalent is to be found very widely). If anything becomes ONE times less, it vanishes, so 200 (or any other number greater than 1) times less is impossible. It must be inverted, with the concentration expressed as one-two-hundredth…. Yes, it is more of a mouthful, but we do endeavor to be scientifically correct, I believe.

    Ian

  2. “””””……Concern about the long-term stability of global gas hydrate deposits is rooted in the potential impact that a large CH4 release might have on global climate. CH4 is ~20 times more potent than CO2 as a GHG, but it oxidizes to CO2 after about a decade in the atmosphere. In recent models, the longer-lived CO2 oxidation product (Archer et al. 2009), not the CH4 itself (e.g., Harvey & Huang 1992), is credited with causing most of the excess atmospheric warming that would follow large-scale dissociation of methane hydrates…….””””””

    What exactly, means “”””””……~20 times more potent……””””””

    I just looked up the list of fundamental physical quantities in my handbook of Physics, and there was no mention of “potent” or “potency”.. I thought those were Biology terms, relating to Viagra or Cialis and the like.
    Couldn’t find “forcings” either; nor the NIST recommended value of “Climate Sensitivity”.

    So a logical explanation of “20 times more potent” in GHG terms, would mean that a single (additional) molecule of CH4 in the atmosphere will absorb 20 times the number of Joules of LWIR radiant energy, that would be absorbed by a single (additional) molecule of CO2; IN THE SAME AMOUNT OF TIME.

    Now I have seen a good many purported atmospheric absorption spectra that include the claimed absorption bands due to H2O, CO2, O3, and CH4, and I don’t recall seeing any such graph, that shows CH4 taking any great swath through the appropriate wavelength range of interest, which I would put at say 0.1 micron wavelength, up to 100 microns wavelength.

    Down at the 0.1 micron end, would be the extreme of the incoming solar spectrum, that likely can split O2 into O, to create O3, and anything that absorbs any solar spectrum, is a cooling influence on earth, since that solar spectrum energy will never reach and be stored in the ocean depths.

    And the earth’s average LWIR thermal emission spectrum reaches from about 5.0 microns up to about 80.0 microns, there being about 98% of the emission in that range. So just where is CH4 wreaking all this havoc.

    And incidently; that CH4 into CO2 morphology, which the clay modeling experts (Archer etal 2009) say is the sneak path to CH4 disaster; just HOW MUCH of the current 399.77 ppm of atmospheric CO2 (Anthony Watts World Climate Widget May 2013) is a direct contribution from the CH4 oxidation pathway; and what fraction of the 1~2 ppm annual increase, and the ~6ppm p-p annual cyclic amplitude does it contribute ???

  3. @2klbofun: I can’t find the reference at the moment, but I recall reading about a Japanese project to do just that.

  4. 2klbofun says:
    July 16, 2013 at 2:02 pm

    Hmmm… if we could just tap those hydrates and use them for cheap fuel…

    It has already begun! PS When do you think we will hit Peak Methane? Greenies are frothing at the mouth.

    BBC – 12 March 2013
    Japan extracts gas from methane hydrate in world first
    Japan says it has successfully extracted natural gas from frozen methane hydrate off its central coast, in a world first……
    _______________________________________
    National Geographic – 27 March 2013
    Pictures: Unlocking Icy Methane Hydrates, a Vast Energy Store
    Japan’s Burning Hope for New Energy

    A flame ripples from a burner on the back of a deepwater drilling rig in the Pacific Ocean off the southern coast of Japan, heralding an energy breakthrough for a power-starved nation……

  5. Ohh they worked it out by simulation on MODELS ……… Well it is obviously completely true and correct, weez all knowz about the models!

  6. “Most of Earth’s gas hydrates occur at low saturations and in sediments at such great depths below the seafloor or onshore permafrost that they will barely be affected by warming over even 10^3 yr.”

    Aaawwww. I was counting on a methane-heated atmosphere to warm my poor chilled bones during my declining years. Now we see it’ll have no more effect than that disappointingly wimpy CO2.

    Those global warming alarmists are such teases!

  7. Actually, the sea floor methane hydrates is what we should be worried about. If the core is being heated and the heat is disseminating outward not from the top down, then hydrates are a concern. It all goes back to the sun’s failure to timely reverse. The shape of the heliosheath has changed, imbuing all bodies with stronger cosmic rays for 100% time coverage. We should worry about the coming big punch not the big bang.

  8. This is great stuff.
    The rabid greenies love screaming about a coming “Methane Armageddon” when you point out the current warming plateau.
    They use methane like some sort of alarmist version of a ‘get out of sceptical jail free’ card. Now I can throw this study back in their faces to shut them up!

  9. So the methane hydrates are not gonna get us, and children in the UK saw lots and lots of snow this year. Now I can go to sleep peacefully, tonight.

  10. The absence of risk of catastrophic clathrate dissociation is not news. The scientists who actually study hydrates have known for years that the risk from any plausible global warming scenario is virtually nonexistent.
    It’s very interesting that Carolyn Ruppel has gone on record saying “never mind”, though. I’ve dealt with her in a professional context, including as co-author. She is a very, very good scientist who has contributed a great deal to the fundamental understanding of stability of methane hydrates.

  11. The CO2 produced by oxidation of CH4 released from dissociating gas hydrates will likely have a greater impact on the Earth system (e.g., on ocean chemistry and atmospheric CO2 concentrations; Archer et al. 2009) than will the CH4 that remains after passing through various sinks.

    De facto translation: The negative effects of CH4 will be less than zero. Which is positive, by the double-negative rule. >;)

  12. Ian L. McQueen says:
    July 16, 2013 at 1:53 pm

    Donning my grammarian stickler’s hat I point out that “The present-day concentration of CH4 in the atmosphere is ~200 times lower than that of CO2″ is impossible (though the equivalent is to be found very widely). If anything becomes ONE times less, it vanishes, so 200 (or any other number greater than 1) times less is impossible. It must be inverted, with the concentration expressed as one-two-hundredth…. Yes, it is more of a mouthful, but we do endeavor to be scientifically correct, I believe.

    Ian

    That’s actually a grammar Nazi’s hat you have there, Ian, and sadly, you follow in their usual path. You argue against what is widespread, common, and perfectly clear usage because it is not logical. Here’s a tip for the interested—English isn’t logical.

    For example, googling the phrase “times lower than” reveals about 14 million instances of things like “Windows 7’s Infection Rates Five Times Lower Than Prior Systems” and “Jobless Claims Four Times Lower Than Expected”.

    And a search for “times smaller than”, which suffers from the same logical flaw, gives us about the same number of occurrences, and lines like “New IBM Microscope Technique Has Resolution 100 Times Smaller Than An Atom”.

    Here’s the thing, Ian. Statements like”ten times lower than” or “ten times smaller than” are understood by everyone, even kids, as meaning “divided by ten”. Nobody sees a headline saying “Jobless Claims Four Times Lower Than Expected” without knowing that they mean a quarter as many claims.

    English doesn’t work because it is logical. It works despite being highly illogical, with many things making no sense at all. Why is it that unravel and ravel come to mean the same thing, when they used to be opposites? But we don’t mind that, because so much of language is metaphorical rather than logical.

    For example, when we say “he lost his head”, even grammar Nazis don’t jump up to say “no he didn’t, he still knows where his head is”, because reasonable people don’t expect the language to be logical.

    Language has one over-riding requirement. It has to be clear. If people don’t understand a construction, it doesn’t get used no matter how logical it is.

    It has a second requirement, only slightly less important. It has to be economical. If it takes a dozen words to say something common, we’ll figure a way to use three words.

    So when we say that diarrhea rates are “six times lower in Togo than in Timbuktu”, everyone knows what that means, and it only takes three words to do it.

    And since everyone does understand it, then it doesn’t make the slightest difference that it’s totally illogical.

    Here’s the problem. Thirteen million people are using “times lower than”. You object. Thirteen million to one … do you expect, not to win, but to make even the slightest dent in that? It’s the futility of the grammar Nazi effort that always surprises me.

    w.

  13. george e smith, thanks for the real science and not the climate science spouted by some.

    ”it takes years for the CH4 to dissociate to CO2 and H2O” where does that figure come from? If the IPCC it is wrong. They have the CO2 residence time as 200 years but it has been measured at below 7. I would guess that high in the troposphere dissociation would take but a few hours with all that UV to power the process.

  14. Willis Eschenbach says:

    July 16, 2013 at 10:45 pm

    Why is it that unravel and ravel come to mean the same thing, when they used to be opposites?

    My personal favorite of these types of words is cleave. Cleave can be removing meat from bone. Or it can be an man shall cleave to his wife. Exact opposite in meaning. Love the language.

  15. 2klbofun says:

    July 16, 2013 at 2:02 pm

    Hmmm… if we could just tap those hydrates and use them for cheap fuel…
    ===========================================================

    It would convert all those highly toxic warming gases to much less dangerous carbon oxygen combinations. I know they say it’s stable, but let’s not forget the precautionary principle that greens love.

  16. I have to agree with Ian McQueen. Poor usage is to be avoided and it does not mean that one is a fascist-type in pointing out what is poor usage and what is correct. Up with good grammar. There are persons who will take note and benefit from such corrections. Then there are those who will not or cannot.

  17. Well, I am not sure how the Google search isolated poor Ian, but I can confirm it is at least 13 million to two.

    It is not too difficult to say diahrrea rates in Togo are one-sixth those of Timbuktu.

    James

  18. “””””……mkelly says:

    July 17, 2013 at 7:06 am

    Willis Eschenbach says:

    July 16, 2013 at 10:45 pm

    Why is it that unravel and ravel come to mean the same thing, when they used to be opposites?…..”””””

    Well people who think they are sophisticated, usually are; they just never looked up sophistry, in a dictionary.

    Sometimes, English gets confused by geography. Americans will say; “Professor Einstein will be with us momentarily.” instead of he’ll be here soon. To Brits, (and colonials), that does not mean Einstein will be here IN a moment; it means Einstein will be here FOR a moment.

    I go with the “soon”, as more concise and clearer too.

  19. ‘200 times lower’ has a journalistic punch, a way of (over) emphasizing (depending on your viewpoint). One two hundredth, tho’ accurate doesn’t quite convey the journalistic punch. Often I think it is the punch that is aimed for, and not the ease of expression as someone suggested. Either way, let’s stick to the truth. That 13 000 000 to one just turned 4 333 333 to one on record here. That is some change! ? !

  20. If these things are going to be so dangerous a millenium from now, obviously the only thing to do is to harvest them and burn them so they convert to less harmful CO2. It’s for the children you know.

  21. If anyone is here for a moment then he is here for a short time not in a short time as soon means. Come on, get it right ( meaning correct). OK george e Smith?

  22. If methane would normally need ten years to degrade to the less-warming CO2 and H20, then of course we should be oxidizing the methane as soon as we have access to it. It would be more environmentally friendly than carbon capture and sequestration.
    If we continue to draw off the methane as it reaches large volumes and oxidize it rapidly, we should be averting a real climate catastrophe.
    And if we happen to oxidize it right below a tank of water and then use the byproduct to spin a magnet inside some wires, we could all read about it on the Internet.

Comments are closed.