Petm

Discussion in 'Earth Science' started by Andre, Jun 3, 2006.

  1. Andre Registered Senior Member

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    889
    Silkworm posted this link somewhere:

    http://news.yahoo.com/s/ap/20060601/ap_on_sc/hot_arctic_7

    I think it's worth it's own thread.

    The current difference between the Arctic -20 -40 Celsius and the tropics +35 +45 C roughly 60-70 degrees C. If the Arctic was 20+ degrees, were the tropics boiling?

    So what happened and why was Earth not turned into Venus at that point?

    (like this: http://www.spacetoday.org/SolSys/Venus/VenusPlanet.html )
     
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  3. Andre Registered Senior Member

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    Nobody interested in the solution of the Paleaocene Eocene Thermal Maximum and the enigmatic tropical swimming paradice in the Arctic sea??

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    Perhaps it helps to have a good look at the Arctic Ocean and think, the solution is staring at your face:

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    It's really not that complicated, just a trick of mother Earth, now where would that warm pool be coming from and what has clathrate to do with that?

    How could I have overlooked this so long?

    This is how the PETM started:

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  5. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Very interesting Andre. For others as ignorant about clathrates as I was, I suggest reading:

    http://ethomas.web.wesleyan.edu/ees123/clathrate.htm

    I have always wondered about how the Earth escapes from ice ages. The high albedo of ice and snow seems to make this impossible. There is the "snowball Earth" explanation (Completely iced over Earth can not get rid of green house gases that Volcanoes emit by absorbing them into the oceans.) but I do not buy that one. Now a new idea seems possible to me and as others posting here know much more than I do in this area, I want their comments.

    First I note a fact, I learned from the work I have done in the geothermal energy area. Everyone associates geothermal energy with magna near the surface, but we were investigating the more generally available low grade heat (for cleaning bottles, processing chickens, etc., not electric power) available on the Eastern shore of Maryland - There the sediment is 5000 or more feet thick and serves as a "blanket" to keep the deeper layers hot (well at least, quite warm). I am way out of my field and as far as I know this low grade heat is not used. Perhaps other areas are more attractive, but we were restricted to look in Maryland by our funding.

    I also think Ice Ages tend to end rather quickly (Is that correct?)

    Now for my idea (perhaps Andre already has it also):

    If the deep parts of the ocean form solid clathrates that contain a large volume of green house gases, and accumulate for 10s of thousands of years during an ice age, perhaps this solid layer on ocean floor acts like a blanket (same as the terrestrial sediment on Md's Eastern shore). Being solid it will certainly stop the normal convective cooling that quickly transports heat to the ocean surface. At some condition of clathrate layer thickness the temperature at the bottom of the layer will make the clathrate decompose, despite the pressure. Convection will then be possible and rapidly "eat away" at the solid clathrate layer still above (and at lesser pressure). When, this covering cap of solid clathrate is destroyed, a gigantic "burp" of green house gases* occurs and the ice age rapidly ends, despite the high albedo of the ice.

    What do you think of this idea?
    -------------------------------------------
    *and of course a rapid and very significant positive step in the surface temperature of the ocean in general as this hot, previously confined bottom water rises and spreads out on the surface. Note there may be little mixing of it with the cold water it is rising thru - It will come up as "fingers" driven by the "Taylor Instability" that it is. More on this and a "variable sun" idea for ending ice ages in my book Dark Visitor - see site unde my name for how to read for free.
     
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  7. Andre Registered Senior Member

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    I think you are very close and some mechanism like that could act to sustain a clathrate decompostion event. So once it started it will not stop until the last clathrate has gone. And it may have assisted in ending ice ages like the last one by sending huge amounts of warm surface waters into the Arctic. This has most likely happened 14-13,000 years ago, by the amazone fan and somewhere between 11,600 and 8200 years ago, by the Storegga slide, causing huge climate changes (paper about that is in review).

    But the PETM event 55 million years ago was something else, a couple of orders of magnitudes more intens than those burbs that ended the last ice age, with the Arctic changing into a warm swimming pool? ...or?

    But what triggered that event? I think the catastrophic filling of the empty Arctic Ocean basin, after slowly forming due to the receding continents via the obvious vore between Svalbard and Greenland, lowering sea levels perhaps a few dozen meters within a very short period, which appeared to be enough pressure relief to trigger the clathrate to become unstable on a world wide scale.

    Thus several million cubic kilometers of warm surface waters plunged into the basin, including their (tropic) biota, completely fooling the researchers 55 million years later.

    But there is more. Would this explain the sudden greenhouse gas increase? and how?
     
  8. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Glad you think my idea has some sense. Apparently it is not same as idea you were suggesting for PETM event. Is it an idea that you have not seen in the literature dozens of times?
    I like that - always good to remind Ph.D.s of how little we really know "for sure".

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    Geology is not my strong point, but I seem to recall reading about a dramatic emptying (or was it filling?) of area about size of Texas in US NW long ago. Your explanation for the PETM, which I had never even heard of before today, is of course a one time event. My idea for the ice age is an erratic period reoccurrence mechanism, which is what they have been. Both sides of the temperature variation have positive feed back - I have already explained the melting side. The ice forming side has initial cooling that permits the formation of the clathrate solid "film" on bottom that immediately reduces the escape of core heat slightly under the Earth that is ocean. This permits the cooling to accelerate - etc. positive feed back for both the ice age forming and ice age ending transitions.

    If you know of some prior publishing version of my idea , where is it?

    I do not read "ice age literature." (Too "old and cold" for me. I like "younger and hotter."

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    )
     
  9. Andre Registered Senior Member

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    889
    Billy, that PETM idea in my post was born this morning at 8.58 am. Before that and when I started this thread I was thinking of a Arctic ocean that was open to the other oceans, which required clathrate events as forces to propell the tropic waters towards the Arctic like in the last ice ages. But according to the Articles it was not, it was an isolated basin, that triggered the idea.

    We have a vivid discussion about the scenario here:

    http://www.ukweatherworld.co.uk/forum/forums/thread-view.asp?tid=1979&start=1

    The first notion about a possible relation between ice age climate shifts and clathrate comes from James Kennett, the Clathrate gun. Earlier this year Todd Sowers thought he had found proof against it, but he was a bit too quick, anyway a list of references here:

    Archer, D., 2006. Methane hydrates and anthropogenic climate change. Manuscript submitted 12-07-05. http://geosci.uchicago.edu/~archer/reprints/archer.ms.hydrate_rev.pdf

    Björck, S., Bennike O., Rosén P., Andresen C., Bohncke S., Kaas E., Conley D., 2002. Anomalously mild Younger Dryas summer conditions in southern Greenland. Geology May, v. 30; no. 5; pp. 427–430.

    Bouriak, S.,. Vanneste M, Saoutkine A., 2000. Inferred gas hydrates and clay diapirs near the storegga slide on the southern edge of the Vøring Plateau, offshore Norway. Marine Geology, 163, pp.125–148.

    Brook, E.J., Harder S., Severinghaus J., Steig E.J., Sucher C.M., 2000. On the origin and timing of rapid changes in atmospheric methane during the last glacial period. Global Biogeochemical Cycles, 14(2), pp. 559-572.

    Bryn, P., Berg K., Forsberg C.F., Solheim A., Kvalstad T.J., 2005. Explaining the Storegga Slide, Marine and Petroleum Geology, Volume 22, Issues 1-2 , January- February 2005, pp. 11-19.

    Buffett, B., Archer D., 2004. Global inventory of methane clathrate: Sensitivity to changes in the deep ocean. Earth and Planetary Science Letters 227, pp. 185-99.

    Bunz, S., Mienert J., Berndt C., 2003. Geological controls on the Storegga gas-hydrate system of the mid-Norwegian continental margin. Earth and Planetary Science Letters, 209, pp. 291–307.

    Chebykin, E.P., Edgington D.N., Grachev M.A., Zheleznyakova T.O., Vorobyova S.S., Kulikova N.S., Azarova I.N., Khlystova O.M., Goldberg E.L., 2002. Abrupt increase in precipitation and weathering of soils in East Siberia coincident with the end of the last glaciation (15 cal kyr BP). Earth and Planetary Science Letters, Volume 200, Issues 1-2, 20 June, pp. 167-175.

    Clark, J.F., Washburn L.,.Hornafius J.S, and Luyendyk B.P., 2000. Dissolved hydrocarbon flux from natural marine seeps to the southern California Bight. Journal of Geophysical Research-Oceans 105 (C5), pp. 11509-11522.

    Dickens, G., 2001. The fate of past gas: What happens to methane released from a bacterially mediated gas hydrate capacitor? Geochemistry Geophysics Geosystems Forum Volume 2, January 9.

    Evans D., Harrison Z., Shannon P.M., Laberg J.S., Nielsen T., Ayers S., Holmes R.,. Hoult R.J, Lindberg B., Haflidason H., Long D., Kuijpers A., Andersen E.S., Bryn P., 2005. Palaeoslides and other mass failures of Pliocene to Pleistocene age along the Atlantic continental margin of NW Europe. Marine and Petroleum Geology, Volume 22, Issues 9-10, November-December, pp. 1131-1148.

    Grant, N., Whiticar M., 2002. Stable carbon isotopic evidence for methane oxidation in plumes above Hydrate Ridge, Cascadia Oregon Margin. Global Biogeochemical Cycles, 16 (4). Grayson, D., Meltzer D., 2003. A requiem for North American overkill. Journal of Archaeological Science Volume 30, Issue 5, May, pp. 585-593.

    Heeschen, K.U., Collier R.W., de Angelis M.A., Suess E., Rehder G., Linke P.,
    Klinkhammer G.P, 2005. Methane sources, distributions, and fluxes from cold vent sites at Hydrate Ridge, Cascadia Margin. Global Biogeochemical Cycles, 19 (2).

    Hill, J.C., Driscoll N.W., Weissel J.K., and Goff J.A., 2004. Large-scale elongated gas blowouts along the US Atlantic margin. Journal of Geophysical Research-Solid Earth, 109 (B9). Hoehler, T.M., D.B. Albert, M.J. Alperin, and C.S. Martens, 1999. Acetogenesis from CO2 in an anoxic marine sediment. Limnology and Oceanography, 44 (3), pp. 662-667.

    Kennett, J.P., Cannariato K.G., Hendy I.L., and Behl R.J., 2000. Carbon isotopic evidence for methane hydrate instability during quaternary interstadials. Science, 288 (5463), pp. 128-133.

    Kennett, J.P., Cannariato K.G.,. Hendy I.L, and Behl R.J., 2003. Methane hydrates in Quaternary climate change: The clathrate gun hypothesis. Publisher, American Geophysical Union, Washington, DC.

    Maslin, M.A., C. Vilela, N. Mikkelsen and P. Grootes, 2005 “Causation of the Quaternary catastrophic failures of the Amazon Fan deduced from stratigraphy and benthic foraminiferal assemblages.” Quaternary Science Review, volume 24, Issue 20-21, 2180-2193 (2005).

    Maslin, M.A., Mikkelsen, N., Vilela, C., Haq, B., 1998. Sea-level– and gas hydrate– controlled catastrophic sediment failures of the Amazon Fan. Geology, v. 26, pp. 1107– 1110.

    Maslin, M., Owen M., Day S., Long D., 2004. Linking continental-slope failures and climate change: Testing the clathrate gun hypothesis. Geology, 32 (1), pp. 53-56.

    Mienert, J., Andreassen K., Posewang J., Lukas D., 2000. Changes of the hydrate stability zone of the Norwegian margin from glacial to interglacial times. Gas Hydrates: Challenges for the Future, pp. 200-210.

    Mienert, J., Vanneste M., Bunz S., Andreassen K., Haflidason H., and Sejrup H.P., 2005. Ocean warming and gas hydrate stability on the mid-Norwegian margin at the Storegga Slide. Marine and Petroleum Geology, 22 (1-2), pp. 233-244.

    Milkov, A.V., 2000. Worldwide distribution of submarine mud volcanoes and associated gas hydrates. Marine Geology, 167 (1-2), pp. 29-42.

    Rehder, G., Brewer P.W., Peltzer E.T., Friederich G., 2002. Enhanced lifetime of methane bubble streams within the deep ocean. Geophysical Research Letters, 29 (15).

    Rehder, G., Keir R.S., Suess E., Rhein M., 1999. Methane in the northern Atlantic controlled by microbial oxidation and atmospheric history. Geophysical Research Letters, 26 (5), pp. 587-590. Ritchie, J.C., 1987.

    Sowers, T., 2006. Late Quaternary Atmospheric CH4 Isotope Record Suggests Marine Clathrates Are Stable. Science, Vol. 311, 10 February, pp. 838-840.

    Thorpe, R.B., Pyle J.A, Nisbet E.G., 1998. What does the ice-core record imply concerning the maximum climatic impact of possible gas hydrate release at Termination 1A?, in: Henriet, J.-P., Mienert J., 1998. Gas hydrates: relevance to world margin stability and climate change. Geological Society Special Publication, 137: pp. 319-326.

    Valentine, D.L., Blanton D.C., Reeburgh W.S., and Kastner M., 2001. Water column methane oxidation adjacent to an area of active hydrate dissociation, Eel River Basin. Geochimica Et Cosmochimica Acta, 65 (16), pp. 2633-2640.

    Vogt, P.R., Jung W.-Y., 2002. Holocene mass wasting on upper non-polar continental slopes-due to post-glacial ocean warming and hydrate dissociation? Geophysical Research Letters, 29, 55.1–55.4
     
  10. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    23,198
    Andre:
    Thanks for the references. I visited the first. Looks like you are gaining on Peter.
    I will try to read the two papers by Kennet,JP and the one by Sowers in your long list first as they seem to be most directly related to my "positive feed-back, clathrate oscillator" theory that explains both of the greenhouse/icehouse transitions associated with ice age start and end. Perhaps Kennet has preceeded me, but he may not have mentioned my "clathrate blanket effect" and the importance of start of convection at the bottom of the clathrate layer as cause of the "big fart" and rapid end of the ice age.

    For me to read JPK, I think it is necessary to go to a university library, unless I can learn how to get these papers on line, or you have copies you can Email me.

    I will now begin to explore what I can do on line and check back here to tell if I got to read.

    Exciting times for both of us. (Million volt ideas etc.) If I turn up anything that helps your theory, I will send to you by PM. Do same for me.

    PS - Nice that these forums time stamp and record the develpment of ideas. - Science historians must love them.

    Edit up date 1:
    JPK's Science paper abstract contains:
    "...Gas hydrate stability was modulated by intermediate-water temperature changes induced by switches in thermohaline circulation. These oscillations were likely widespread along the California margin and elsewhere, affecting gas hydrate instability and contributing to millennial-scale atmospheric methane oscillations."
    Billy T comment:
    Thus it does not seem he is into the mechanistic details of my "positive feed-back, clathrate oscillator" I will look else where before buy this one.

    Edit up date 2:
    T. Sowers' Science paper abstract contains:
    "One explanation for the abrupt increases in atmospheric CH4, that occurred REPEATEDLY during the last glacial cycle involves clathrate destabalization events. Because marine clathrates have a distinct deuterium/hydrogen (D/H) isotope ratio, any such destabilization event should cause the D/H ratio of atmospheric CH4 ({delta}DCH4) to increase. Analyses of air trapped in the ice from the second Greenland ice sheet project show stable and/or decreasing {delta}DCH4 values during the end of the Younger and Older Dryas periods and one stadial period, suggesting that marine clathrates were stable during these abrupt warming episodes."
    Billy T comment:
    Part I made all caps or bold makes me think he is concern with lesser variations than onset and end of ice ages, not being due to clathrate destabalization. It true, it is unimportant for my theory of cause of end (and start) of ice ages. You know more than me. Do you agree? Thus not buying this one either, yet.
     
    Last edited by a moderator: Jun 8, 2006
  11. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    23,198
    Andre (see earlier post also)
    A google search of:
    "Methane hydrates in Quaternary climate change: The clathrate gun hypothesis. and American Geophysical Union"
    Turned up a gold mine of infro. I will read some and get back here. I will not modify prior post more as do not want to screw up time stamps by edit more than I already have.

    Just re-visited your first ref again. Contary to some recent posts there, I think the fresh water in artic basin at 50mybp supports both our theories. I.e. At 55mybp the salt water rushed in (your theory) and the clathrate gun fired (Kennet's theory) rapidly warming entire Earth via the greenhouse gas fart and this fart causing rapid melt of ice stored on land. This flood of fresh water converted the basin to fresh water, at least on top.

    But I suspect it was less than the 5mypb than 55-50 the new core data suggest. - How accurate is the timing of the core indicated events?

    At 50mybp the new connection you suggest to ocean is still very narrow. - No problem to maintain a salt gradient along it, especially with net fresh water flow into the N. Atlantic ocean.

    Edit 1:
    JPK's AGU book ( )summary contains:
    "Late Quaternary climate oscillations led to successive intervals of methane hydrate stability and accumulation during coolings, followed by hydrate dissociation and CH4 release during warmings. These changes occurred because of frequent, rapid temperature oscillations in upper intermediate waters over broad areas of the upper continental margins in the depth zone of potential hydrate instability. We present evidence suggesting that these temperature oscillations resulted from changes in the source of intermediate waters between low and high latitudes. Cool episodes were marked by increased equatorward expansion of cooler intermediate water from northern (North Pacific and North Atlantic Intermediate Waters) and southern latitudes (Antarctic Intermediate Water)."
    Billy T comment:
    Clearly he has a "top down" mechanism for hydrate dissociation in contrast to my "bottom up" (convection driven hydrate dissociation starts at bottom of hydrate layer) POV. He may well be correct, but as this alternative is my "bottom convection replacing conduction heat transfer accelerates the hydrate dissociation" idea, I intend to explore it farther.
    I am encouraged by the thick "clump of hydrate" I saw in photo at:

    http://communications.uvic.ca/releases/release.php?display=release&id=171

    That is exactly what I would expect as the residue of bottom layer hydrate dissociation. - I.e. pieces would be bypassed once the trapped, gas-rich water that was hydrate begins to escape upwards in Taylor instability fingers.

    I can almost see the Taylor instabilities fingers streaming upwards thru the cracks you see in this photo!

    I would not expect such clumps and cracks if the hydrate dissociation was by contact with a warmer water layer above it. In this case, any "hydrate finger" sticking up into the warmer water would be rapidly "eaten off" by the warm water, not left to appear as "hydrate clumps" do in the photo. Likewise it is hard to understand how warm water above the hydrate could have formed these cracks.

    Edit 2:
    JKP seems to be defending against the isotope attack; I can not read the reply in Nature. www.nature.com/news/2006/060206/full/060206-9.html
    Can you?
    In some ways I hope his "top down" model of hydrate dissociation does have problems as that opens the door wider to my "bottom up" model.
     
    Last edited by a moderator: Jun 8, 2006
  12. Andre Registered Senior Member

    Messages:
    889
    Hi Billy,

    Unfortunately I was rather tied up in my regular job today and yes that 50My fresh water flood is puzzling but as usual, there are conclusions there. One should only look at facts. There will be another brainwave in due time, it's getting to be a habit, which can be annoying actually because it causes me loads of work, studying and writing and a h..of a lot of energy to get the Peters of this world to listen. I was really not trying to "solve" the PETM. It just so happened.

    About clathrate triggering mechanism, I'm more with you and there is most definetly an irregural cycle, the Storegga are in 100ka, causing the big burps and the Amazon Fan in 10ka's causing multiple smaller burps. Important is to remember that Clathrate floats. When sediment is mixed within, the compostion may be heavier than water but a simple earthquake could disturb the balance, disrupting sediments. This may send clathrate rich chunks to the surface, then, after the destablisation would start during the ascend, the pressure above the clathrate field is released causing the chain reaction.

    I'll send you a paper that you will not find on the net. For the rest, got a few gig of pdf's here, collected in the course of the years, most actually by my buddy, Nilequeen. Many authors are happy to send them but unfortunately evade any serious discussion afterwards.

    The real key studies are:

    Evans D., Harrison Z., Shannon P.M., Laberg J.S., Nielsen T., Ayers S., Holmes R.,. Hoult R.J, Lindberg B., Haflidason H., Long D., Kuijpers A., Andersen E.S., Bryn P., 2005. Palaeoslides and other mass failures of Pliocene to Pleistocene age along the Atlantic continental margin of NW Europe. Marine and Petroleum Geology, Volume 22, Issues 9-10, November-December, pp. 1131-1148.

    Bryn, P., Berg K., Forsberg C.F., Solheim A., Kvalstad T.J., 2005. Explaining the Storegga Slide, Marine and Petroleum Geology, Volume 22, Issues 1-2 , January- February 2005, pp. 11-19.

    Maslin, M.A., C. Vilela, N. Mikkelsen and P. Grootes, 2005 “Causation of the Quaternary catastrophic failures of the Amazon Fan deduced from stratigraphy and benthic foraminiferal assemblages.” Quaternary Science Review, volume 24, Issue 20-21, 2180-2193 (2005).

    Mienert, J., Vanneste M., Bunz S., Andreassen K., Haflidason H., and Sejrup H.P., 2005. Ocean warming and gas hydrate stability on the mid-Norwegian margin at the Storegga Slide. Marine and Petroleum Geology, 22 (1-2), pp. 233-244.

    Looking forward to interesting times.
     
  13. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    23,198
    Hi Andre:

    Fortunately I retired 12+ years ago, so despite only being interested in this for two days i am learning fast. PS I know well what you mean by "...not trying to "solve" the PETM" problem. I was not trying to solve the Genuine Free Will problem (How GFW could be consistent with physics) when a solution "fell out" of my studies of vision. (I had struggled with that one for years and given up on it as a nut too tough to crack by humans.) I will not give referrence now as I think both you and I do not want to be diverted from these exciting developments.

    Based on following, I think JPK gets credit mainly for the clever phrase "clathrate gun" and credit for idea behind it belongs to Jerry Dickens of Rice Un.

    "... In the early 1990's, Jim Kennett of Scripps Institute of Oceanography and his colleagues noticed that during an extremely short amount of time (geologically speaking) at the transition between the Paleocene and Eocene epochs, carbon isotope ratios everywhere (the deep sea, on land, at the poles and in the tropics) suddenly changed to favour the lighter 12C isotope of carbon at the expense of 13C. ...
    In 1995, Jerry Dickens of Rice University suggested that the only conceivable perturbation to the global carbon cycle to fit these data was a massive input of light carbon that had been stored as methane clathrates, which are observed to be particularly high in 12C. Nothing else could be as fast-acting or have enough of the lighter isotope to have had the observed effects. Given that both CH4 and it's oxidization product CO2 are greenhouse gases, this might explain the global warming as well.
    Subsequent work, including atmospheric chemistry studies by myself and Drew Shindell of NASA GISS, have confirmed that this hypothesis is still the most likely candidate, although the initial triggering mechanism is unknown."

    From: www.giss.nasa.gov/research/features/methane/
    which is a good general overview for anyone following Andre and my exchanges.

    I especially like the last seven words, now bold above, as I think my idea may be the trigger. If I write a paper, perhaps I will call it "A Trigger for the Clathrate Gun"

    I am sure you know there is an omission above in: "...both CH4 and it's oxidization product CO2 are greenhouse gases." I.e. the other oxidation product, H2O, is a dam effective greenhouse gas also, and this is very important in the dry high atmosphere.
     
    Last edited by a moderator: Jun 8, 2006
  14. Andre Registered Senior Member

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    889
    The real trigger of the PETM Clathrate events, however is the global eustatic sea level lowering, during the catastrophic filling of the Arctic basin. Several studies indicate that without, knowing the cause.

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    . You will also see Maslin struggling to find the trigger for the 14-13Ka Amazon Fan event with quickly rising sea levels (melt water pulse 1A). That one really can only be tectonic.

    About all the global warming stuff, here is a lot of affirming the consequent fallacy here. It may be temperature but you can't thrust them when other things are going on
     
  15. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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  16. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    You may be correct, but I want to see a phase diagram that tells how much temperature reduction is required to compensate for a meter drop in the sea, etc.

    Insert by edit: I think I now have a source giving the "stability boundary" as fct of P and T for naturally formed methane hydrates at: www.searchanddiscovery.com/documents/abstracts/2004hedberg_vancouver/extended/wright/wright.htm
    but must stop working now after only skimming. (Prior to this edit, I had asked Andre for one at this point in post.) End of insert.

    For your one time event, probably both P and T changes worked together to make the world's biggest fart. I.e. if the artic basin was partially filled with hydrate on the bottom the inrush of warmer water dumped that methane too. - I have no view on quantity of water in it before your "Big Niagara." - You seem to think it was dry, but I am not persuaded of that yet.

    I tend to lean more to a brackish water inland lake, but admit it might be well below sea level. Rain and snow were not zero and at that latitude (if it was at high latitude back then) sun would not make evaporation rate high to dry it. As others will also need to be persuaded that there was a "Big Niagara," you must support the existence of a basin with elevation well below sea level, not an near sea level inland lake. I mention this to be helpful, not critical.
    --------------------------------------------------------------
    In: www.minsocam.org/MSA/AmMin/TOC/Abstracts/2004_Abstracts/AS04_Abstracts/Chakoumakos_p1153_04.pdf
    you will find following interesting (at least to me) statements:

    "As crystalline materials, clathrate hydrates have anomalously
    low thermal conductivity
    , approaching glass-like behavior at low
    temperatures."
    Billy T comment: "excellent blankets"
    and
    "Most physical property measurements are based on studies of laboratory-synthesized samples."
    Billy T comment: These lab samples float, you tell me, and I believe, but even the rather white, clean-looking, "hydrate glacier" 850 feet below the surface seen it the photo with cracks in it that I like does not float, even in sea water.
    I would expect that the organic matter that is the carbon food for the anaerobic bugs making the methane is usually mixed in "naturally formed" methane hydrates so fact that the pure, lab-made, hydrates float is not much of a reason to discard my "bottom up" trigger.
     
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  17. Andre Registered Senior Member

    Messages:
    889
    That's double the same. This is what we send to Sciencemag:

    Not that they publish things like this of course.
     
  18. Andre Registered Senior Member

    Messages:
    889
    Yes, I understand that. Well the deep Arctic basin is there, no doubt, and the currect plate tectonic suggest that the Arctic was isolated. That's also what the Nature publication suggests. The rest is hypothetical logic. If ... then ... and all available evidence explained. If not..... then not .... and nothing explained.

    While your mechanism may very well be a strong positive feedback, clathrate alone cannot explain the tropical swimming pool in the Arctic, because the (near) isolation of the basin. Greenhouse effect is not feasible here due to the saturation effect. Moreover the effect of CH4 is usually grossly exagarated.

    You can see in this table of modtran3 runs that CO2 is 2-5 times stronger at equal concentrations (last column).

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    and in the graph with logaritmic scales:

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    The world may have been several degrees warmer due to greenhouse effect but climates were also dramatically more moist according to several proxies, indicating more cloud cover, indicating less insolation. So no runway climates and no explanation of tropical Arctic swimming pools.
     
  19. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I agree. I did not intend to imply in anyway, that my idea was in contrast or challenge to your "Big Niagara." My Idea, I am coming to understand, is fully correct, but a bout 3 years too late to set the world on fire (well maybe just end and ice age

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    ) It is at most a minor correction to the mechanism by which the hydrate is decomposed.

    I am about equally glad I thought of it independantly and that I now know how ice ages can end - I have long recognized that prior theories ("Snowball Earth etc.) were silly and totally lackinng in the power to overcome the high albedo (~.85) of ice in ice age.
     
  20. Andre Registered Senior Member

    Messages:
    889
    Well the Big Niagara can still extinguish the fire that Sluis et al 2006 Moran K et al, 2006, Brinkhuis et al 2006 ignited in Science 1 June.

    The ending of the ice age BTW is not nearly settled yet. Looking at the Last Glacial Maximum, the initial melting is reporten around 26 ka in Alaska, around 19ka in the Southern hemisphere in general and the big Laurentide receded clearly around 17 ka but the first clathrate event, the Amazone fan ignited 14,600 ka and is seen in the ice cores of Greenland as Bolling Allerod event. The second ignition, the Preboreal, 11,662 years ago comes from the decomposition of the Storegga area
     
  21. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

    Messages:
    2,559
    Interesting topic.

    Methane hydrates are being looked at by some as an untapped energy reserve, and they want to 'mine' the seafloor for them.

    I've also read that sudden releases of methane can sink a ship that is sailing on the surface overhead, when the average density of the water drastically decreases from all the gas rising to the surface. I believe the "Bermuda Triangle" region has such methane hydrates, and this was hypotheszed as one of the explanations for some missing ships.

    I've also read that rising sea-level temperatures might unleash sudden releases of methane, increasing that particular 'greenhouse gas'.

    So what causes methane hydrates to form in the first place? Is this primordial methane, entrapped in the earth, that slowly leaks upwards and hydrates with the cold bottoms waters? Or is the methane of other origins - e.g. 'swamp-gas' type from rotting life-forms?

    Your thoughts on these topics would be appreciated.

    Also, on a similar vein, I've read that the Mediterranean was once ocean-blocked (at the Strait of Gibraltar), and it evaporated, leaving a thick layer of salt, which underlies the current bottom, after having been silted over for many millenia. I don't have the time frames on that, however. It then broke open to the sea again, with a waterfall lasting centuries, refilling the basin. And, the Black Sea also did the same, though that time only a few millenia ago, so it was recorded in history by the survivors, giving rise to several variations of the Noah story.

    Are their other areas besides the Arctic, and the ones I've mentioned, that underwent catastrophic filling by the sea?
     
  22. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Messages:
    23,198
    I am so new to all his that I do not know what you are referring to. I will venture an opinion on how ice ages end: It is caused by the hydrates decomposing, but perhaps need not be in the same century in both hemispheres as trans-equatorial mixing may be too slow. In my searches, however at least one paper I read disputes this as it claimed that the atmospheric change came after the ice had started to melt, not before or during the melting. Certainly, some additional increase must be expected because as the ice melts, the sea rises, and all that organic matter, from bird shit to trees, that was storing carbon on the exposed coastal shelf is now being flooded and decompsing anerobically in part. Thus,even if it is true that the peak of the greenhouse gases comes after the start of the melting, that seems possible/reasonable to me.
     
  23. Andre Registered Senior Member

    Messages:
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