You may want to read the paper that I send yesterday. Unraveling the ice ages needs a lot of interpretation of evidence, the affirming the consequent fallacy. For instance the dating of southern hemisphere warming is thought to be indicated with a stable isotope jump (dD, d18O) in the ice cores of the Antarctic (Vostok, Dome C etc). For instance, dating of low accumulation cores is very hard without annual stratification visual, so one is depending on estimating accumulation rate and compression rate between hard dating points. So the assumption is made that both temperature and precipitation (accumulation) and isotopes corrolate 100%, based on this the annual layering is reconstructed, and based on this ,the dating is reconstructed. It seems that there is no hard dating point between some 11000 years ago and 28000 years but the assumed warming point 17000 years is somewhere in the middle and hence highly subceptible to errors. In this PhD thesis, here you can see the potential error with that assumption: http://www.phys.uu.nl/~helsen/PDF/thesis.pdf The big problem is that the sudden (clathrate induced) isotope / precipitation spike goes way outside of the parameter range and hence gives a false dating conclusion. The Greenland ice cores have a much higher accumulation rate and consequently are much better datable. But the result is that the dating of warming get's more and more enigmatic (28 - 19 - 17 - 14.6 thousend years ) Take your pick. These problems are all caused by not considering the clathrate events in the equation. For a complete overview of all this research perhaps check the mega work of Spence Weart: http://www.aip.org/history/climate/ However, without Clathrate, all conclusions are worthless/ We have to get back to the basics.
I think we found our Niagara here: http://www.agu.org/cgi-bin/agubooks...tro=OSGM1494149&order=&book=&topic=OS&search= Smoking gun?
New abstract Andre et al, (2006) Understanding the Paleocene Eocene Thermal Maximum, a reconstruction Keywords: Paleocene Eocene Thermal Maximum, clathrate, Laurasia, Turgay strait Abstract The Paleocene Eocene Thermal Maximum is characterized by enigmatic proxy evidence suggesting warm climates, and, as inferred by numerous publications, massive marine methane hydrate (clathrate) destabilization events. The recent discovery of a near tropical Arctic ocean however requires revisiting existing hypotheses, including greenhouse forcing, about the trigger and the cause of events of the PETM. Here we propose that alternately the same proxy evidence, all combined, could have been caused by another mechanism. After the breakup of the Pangea supercontinent some 200 Mya, North America moved in a semicircle clockwise towards the north, hinging around the Greenland - Svalbard area until Alaska and Beringia made contact. Thus the Arctic see became isolated and had no longer contact with open oceans. Then the evaporation of the Arctic inner sea exceeded accumulation for a prolonged period causing a significant sea level lowering in comparison with the rest of the oceans. Furthermore, the tectonic movements of the plates may have enlarged the Arctic basin as North America continued to move progressively to the south west, lowering the sea levels further. At the start of the Eocene, 55Ma ago the Turgay Strait, splitting up Siberia from North to South, made contact between the virtually empty Arctic basin and the near tropical Thetys sea and the Arctic basin started to fill rapidly with warm surface waters of the Thetys sea, not only transporting alien biota towards the Arctic but also warming up the area. The resulting abrupt sea level drop of some 15-30 meters in a very short time caused a secular destabilization of the marine methane hydrates, which explains the remaining proxy evidence pertaining isotope excursions. Hence the empty-Arctic-basin-hypothesis appears to be firmly backed by all available evidence, significantly weakening the case for the Palaeocene Eocene Thermal Maximum to be explained as an enhanced Greenhouse forcing scenario. We propose some further research to test this hypothesis.
To Andre: Thanks for the copy of paper. I have read it now, but not too carefully. I am falling behind as there is too much for me to quickly assimilate. For example. I don’t know what ‘roiling water is. First time I saw it in your paper I thought it a typo for “boiling” but not now that I has been repeated - It must have something to do with lots of rising bubbles. I happen to know that the breaking of bubble is what give a running stream the sound than people like to hear. Perhaps the methane bubbles rising in such quantity over a large area make the water “roar” and look like it is boiling, hence “rioling water”? Any way you will enjoy learning what the Wooly Mammoth reported to the Wooly Hippo when he struggled back thru the mud: Wooly Manmoth: “You were right. - All these recent rains are because of that new lake of warm water and the vapors rising from it. That roar is from a huge water fall. There seems to be an inexhaustible supply of water for that water fall and the lake is still rising. We better get to higher ground.” Wooly Hippo replied: “You told me to wait here and I did. My legs are now stuck in the mud and I can’t move. You go on without me. I will be OK, the lake will not come this high and when the rain stops, I will get free.” Wooly Mammoth: “OK. But, it is so slippery even on this small grade, that I can’t go any higher. Woops, I am sliding backwards, down towards the lake! You are lucky to be stuck in the mud.- I fear I am a goner - I can‘t swim like you can.”
roiling adj : (of a liquid) agitated vigorously; in a state of turbulence; "the river's roiling current"; "turbulent rapids" [syn: churning, roiled, roily, turbulent] Quite a story of the mammoth and the lake but think for a "warm lake" a warm Arctic ocean. See especially MacDonald et al: which was caused by the Storegga clathrate event, propelling the surface waters to the North That made it a whole lot easier to understand the PETM.
So if all this was confusing, let's complicate things a wee bit more, the fresh water arctic. Remember that one of the articles in Nature was about fresh water? Azola ferns (duckweed) in the Arctic around 49Million years, 6 million years after the Paleocene Eocene Thermal Maximum the arctic ocean appeared to be fresh water. I knew that it would happen, there would be an idea in due time. Due time is now (fortunately, this time it's somebody else with an unusual idea, Malcolm McKenna): http://www.agiweb.org/geotimes/oct03/WebExtra102403.html#arctica and http://www.coloscisoc.org/news/2004/newsletter.0401.pdf No things do not add up for the PETM itself. Doesn't explain the tropical swimming pool, so the andre-hypothesis remains superior. However, it's an excellent explanation for the Arctic to become fresh after the opening of the Turgay(i) strait, when the clathrate events caused a world wide warm and humid climate, enhancing river outflow into the Arctic lake significantly causing it to become fresh in due time (millions of years).
It was the new Arctic ocean the wooly was speaking of - he had never seen anything but lakes before, so he called it that.
I went there and found: "..."Then, as the North Atlantic seafloor spread rapidly, within a million years or so after the Icelandic bridge formed, it broke apart again," McKenna says, "and Iceland could no longer choke the whole area." The flood of relatively fresh water southward when the {land} bridge broke would have resulted in biological as well as geochemical upheaval. The rejoined Arctic and Atlantic oceans would have had odd isotopic signatures, as colder freshwater and warmer saline water mixed. Also, "deep warm water flooding into the Arctic would have disturbed methane clathrates, ..." I do not know for sure, but it seems to me that both of us are about three years late. I.e. McMenna seems to have your "million volt idea" (Ocean dumping in to below sea level arctic basin, triggering calthrate gun.) and is destroying my "bottom up" Clathrite destruction detail. I.e. A flood of ocean salty water entering the Arctic basin would certainly mix some but also tend, I think, to flow into the arctic depression mainly on the deeper layers under the fresh water and the clathrate heating / decomposition (sadly for me) would be "top down". I do not think I will try to follow this much more. I did think of trying to make my idea more quantative along the following lines: (1) get some data on the average rate of Earth core heat transport to the bottom of the sea, say relatively deep but still only on the continental shelf. (2) Use the thermal conductivity data I found on calthrate to calculate the thermal gradient across a meter of the clathrate, stuck to the bottom by the weight of the included dirt.(3)Assume the temperature at the top of clathrate / ocean water interface is 4 degrees C (approximately the densest ocean water) (4) using the density of clathrate, compute the increase in both pressure and temperature one meter below the ocean /top of clathrate interface. (5) then look at the stability curves I found to see if the increase in pressure one meter down was or was not able to compensate for the slightly higher temperature on meter down from the top /ocean interface. This procedure will tell if the clathrate is destroyed from the bottom up or the top down, as most (except me) seem to be assuming.* I abandon this calculations for two reasons (1)I am lazy, retired, and with no professional interest to even be a footnote in the new end of ice age mechanism story. (2)My approach is basically and equilibrium approach - not at all applicable if there is a sudden over flow of warm water. I.e. it takes time for the warm water heat to get to the bottom and before it does the top clathrate is decomposing. ------------------------------------ *I have the impression that most think the decompsition is triggered by a drop in pressure which is cause by a drop in ocean levels, and I think this correct for the PETM warming, but perhaps My idea is the correct one to give the long term oscillations in and out of ice ages. I.e. the clathrate layer slowing grows during th ice and sea level stable period until the "blanket effect" of the growing clathrate layer raises the temperature of the BOTTOM of the clathrate layer above the stability point and them convective heat transport in the bottom liquid, still trapped under the clathrate, rapidly eat away at the bottom of the clathrate until one day (figuratively speaking) 100,000 years of accumulated methane breaks free thru the cap of clathrate and you have your "roiling ocean" and the start of the global warming that ends the ice age despite the 0.85 albedo of ice. I.e. my idea is a plausible mechanism for ending the ice ages, all ice ages, not just a one time event like PETM. One aspect of my idea I like a lot is that it is a long period clock, but a low quality one in the sense that factor of two variation in the duration of the ice ages is very reasonable (and I think consistent with the data) as the time to build up to the critical clathrate thickness (for start of thermal decomposition at the bottom of the clathrate) is variable. Do you think I should try to test numerically in the 5 step plan above or has it been done?
Not really, he is only making the Arctic a fresh water basin, he does not lower the sea level in the Arctic and he does not explain why the clathrate goes unstable when the fresh water meets the salt water. But there are more clues, the Paleocene climate was warm and not particulary moist, which does not give the Arctic a reason to act differently than the Mediteranian in similar geographic condition. This sea gets saltier, not more fresh because evaporation exceeds fresh water inflow. On the other hand the Eocene climate was very moist and warm, providing conditions for the Arctic to get fresh. Actually the whole PETM sequence is complicated but can be decribed in six distinct steps and two additional to get the Arctic fress as well as the run of channels: 1. Complete hydrological isolation of the Arctic ocean after the break up of Pangea before the PETM 2. Considerable local sea level lowering in the isolation phase due to evaporation and/or tectonic volume changes 3. Opening of one of the water gateways reconnecting the global ocean to the Arctic, most likely the Turgai strait 4. Refilling of the Arctic basin with warm waters with alien biota 5. Eustatic sea level lowering triggering global-scale clathrate destabilization 6. Strongly enhanced ocean currents, propelled by the methane gas bubble streams, changed climates transporting equatorial warmth to colder latitudes causing a moist warm climate. Here the PETM ended but now we can add McKenna's idea: 7. The climate changes cause a net outflow of the salty Arctic waters, to be replaced by fresh water run off of the continents in a very moist climate, causing the Arctic to change into a fresh inner sea with duckweed. between 55ma and 49Ma 8. The opening of the Atlantic passages between Svalbard and Greenland and the Labrador passage causes the inflow of fresh Arctic waters complete with the pondweed of Henk Brinkhuis (Nature article). somewhere after that Phase one was worth one page for describing and twelve references. The re-opening of the Arctic about double that size, including the discussion if it was the Turgai Strait or the Fram Strait (between Greenland and Svalbard). I do think that you have a point with the bottom up approach, perhaps focus on the Amazon fan and talk to Mark Maslin, who has no idea how the clathrate could have been triggered against the countering sea level rise, but I have some ideas too. BTW The 4 degrees for fresh water is definitely correct however, Bottom sea water temps tend to be around 0-2 degrees C, as the temperature - density relationship of salt water is different. I have not seen any publication doing that but there are a lot of things unpublished as I here from a acquitance with hands on expericience. He is convinced that a large part of the clathrate is not of biotic origine but petrogenic, seeping out of fissures but this is not published anywhere.
I will get to your numbered points soon, I hope, but I do not understand this because, to quote him more fully with some bold added by me: "McKenna discussed a dry land corridor, formed by a proto-Iceland, joining the North American and Eurasian continents and separating the Arctic Ocean from the Atlantic. The net effect is "Lake Arctica," the opening of which would have been catastrophic. According to McKenna's scenario, the only outflow from the Arctic at the time was through the Turgai Straits, a relatively thin but long body of water extending south, along the eastern side of the Ural Mountains of Russia. The only water flowing into the Arctic were from freshwater rivers on the continents. "If runoff from the continents was about 2,500 cubic kilometers per year," as it is today, McKenna says, in less than 100,000 years and as little as 50,000, that input could have turned the Arctic Ocean into freshwater, as other researchers have shown. With the only exit south, and no warm water TRAVELING NORTH to the Arctic, the ocean probably dumped cooler brackish water (or possibly freshwater) down the Turgai Straits. Then, as the North Atlantic seafloor spread rapidly, "within a million years or so after the Icelandic bridge formed, it broke apart again," McKenna says, "and Iceland could no longer choke the whole area." Yes, in first two paragraphs above he is "making the Arctic a fresh water lake and also in first paragraph above, noting that there would be great change if it became connected to the Atlantic ocean (my bold in that paragraph) His third paragraph above seems to support the idea that if any thing "lake Arctica" was above ocean level with flow out into the ocean along the channel just east of the Urals ("down the Turgai Strait") Perhaps if that Strait was deep enough and Lake Arctica was not too much higher than the ocean, there may have been some bottom flow of salty ocean water into the lower layers of Lake Arctica. When he states: "...the ocean probably dumped cooler brackish water (or possibly freshwater) down the Turgai Straits." I am 99% sure he is speaking of he Arctic Ocean or Lake Arctica as in prio sentence he was clearly speaking of the Arctic Ocean, but not sure if it was pure fresh water or brackish. (Probably he also considered that salt water might be flowing into the Arctic Ocean while the fresher (brackish) water was flowing out alone the surface. (When there is no wind, I think this happens in the lower reaches of the Chesepeak Bay today. - much like a cold front is tilted as it slips under warm air and we at ground level only see the cold front advancing on us with rain soon to come as the moist warm air is raised and adibatically cooled.) You state, in support of yours being a different idea: "...he does not explain why the clathrate goes unstable when the fresh water meets the salt water." I have two reactions to this: (1)I am not sure he is stating this meeting of waters is the cause/ trigger of the clathrate decomposition, but if he is: (2)perhaps the clathrate that is going to be decomposed was on the bottom of Lake Arctica. If it was filled by land run off at that near polar latitude, then prior to the influx of warmer salt water on the bottom, the clathrate might have been thick (despite my "bottom up mechanism") and stable, but start to rapidly decompose with contact with the warmer salt water FROM THE SOUTH. (Note the TRAVELING NORTH with in the bold section of his text.) Also, there would be some reduction of pressure, if Lake Arctica were slightly above the more southern ocean prior to the start of bi directional flow in the Turgai Strait. You are, if I understand you correctly, very convinced that the Arctic basin was well below the level of the southern oceans. I am not. He seems to think that it was at least slightly higher than the more southern oceans and I have no problem with that. Thus a big burden on you required to support your "big Niagara" when the southern ocean water falls into the basin and in such quantity that the level of the southern oceans is lowered to make the clathrate on their continental shelfs decompose is to give creditable argument that the Arctic basin was dry or at leas a relative low Arctic Lake /Ocean, with surface well below the "southern oceans." One essential thing for you to persuade me of this is that the solar energy absorbed by a Arctic lake/ocean could evaporate more than his estimated "2,500 cubic kilometers per year" - Remember that sunlight is incident at shallow angle, and for approximately 6 months every year of zero intensity! Surely the surface, prior to the clathrate induced warming, is frozen. Thus, at most, probably less at low angle of incidence, 15% is absorbed. 2,500x10^9 m^3 = 2.5x10^18 cubic cm or grams. At (80+540)cal/ gram (I still remember these two heats of water's phase changes!) that is net gain, despite the radiation to space during the 6 month long night!, or 2.48x10^21 calories or with 4.186joules/ cal (amazing what I still remember!) 10.38x10^21joules. Now considering a low-incidence-angle albedo of 0.9 that is 10^23joules of NET sun shining on the ice surface of Lake Arctica in a year. I will let you take it from here as I do not know what annual-average LOW ANGLE PROJECTED area you want to assume for Lake Arctica, but note that when calculating the half hemisphere radiation into space you need a coefficient of emissivity of more than 0.1, perhaps 0.2, since you must be conservative to be convincing. Although your radiative surface is never hotter than 273degree K, it is radiating all 24x(365+) hours and sun is heating always at shallow angle for only 12x(365+)hours even though it is up for 24 in summer. Can you rise to this challenge? I.e. plausibly argue for a "big Niagara" when the southern ocean is connected? I am betting McKenna's "Lake Arctica is slightly higher than the southern ocean is correct, until you can. (I made that guess earlier, before reading him, if you recall.) - Lake Arctica is not where the Dead Sea is, with sun every day and nearly directly overhead on some. Perhaps you may want to work calculation backwards. I.e. note that today's 2.5 cubic kilometers per year is "way too much" for the rivers of cold continents to supply and then calculate what mass of winter ice the sun could "burn off" to make Lake Arctica only appear briefly in the spring thaw and dry up by end of summer. Good luck, but I think (may be wrong) 10^23J is a hell of a lot of solar energy falling on ice covered Lake Arctica, especially if it is low and small as you hope. You may want to think about Mars also. - The atmosphere there is not so thick, but I seem to recall that the CO2 content may make it a better blanket. Perhaps fact there is no ice-covered lake in the craters there may help you. PS -by edit. Just started to read your numbered points - It is (2) I am having the above trouble to swallow. Edit 2: If we grant (2) or you prove it reasonable, I still have slight problem only with (6), but do not think it too important that the warm water flow driven by the "bubble pump" goes far north as the methane in the atmosphere surely does. I think the bubble pump flow id more like a Taylor instability thunderstorm cloud - relatively local with center up and perimeter down flows on very small scale compared to Earth radius. Edit 3: After reading (7) I understand that the freshwater inflow is well after your "big Niagara" fills the basin, caused global temp rise, and the melting ice converts new arctic ocean to nearly fresh water ocean. I was confused on the sequence before - thought it all sort of one event. thanks for giving the sequence so clearly. In spite of this confusion, you still need to argue for / explain why a nearly dry basin. PS 4: I did my undergrad work at Cornell. Lake Cayuga is deep and bottom is 4 degrees even in summer as I recall. Sometimes bottom warms and as a result, details I once knew but forget just now, the lake "turns over." You probably know all about that, but if you don't you should so I mention it. Edit 5: I think your friend may have a good point. Thomas Gold thought all hydrocarbons were a-biotic. However if they are, they should be "miles thick" on the deep ocean floor even if the had to "roll there" from vent forming them elsewhere, I think. I also think, for similar reasons, or perhaps because the ocean trenches are good vents, that despite their youth and possible greater entering thermal flux, the trenches should be "full of clathrate" EXCEPT FOR MY BOTTOM UP ARGUMENT. I do not know much about this either but think the deep ocean and trenches have little clathrate. Perhaps you friend and I should join forces -If he is correct about the origin of the methane and it is true that the deep trenches are clathrate free, it seems very strong proof of my "bottom up" idea. What does friend say about this? If he is correct I bet the deep ocean trenches are relatively short period oscillators, compared to the longer term oscillators that drive the ice age cycles/ clock. Finding a trench with Clathrate in it would be nice. One with your roiling water and methane bubbles if they do not "instantly dissolve" under the extreme pressure in it would be even nicer. Has anyone looked at the dissolved methane content of deep trench water?
Well we have done some thinking too. First about the evaporation of the Arctic ocean and the climate. Typing over a passage from an older study of Ellismere Island (High Arctic Canada) about fauna in the Paleocene: I have had a Metasequoia in my garden, Azolla is duckweed. Those are very rare nowadays on Ellismere Island. Now there are several possibilities. Either the world had contempt for the current climatologic basis of lower temperatures of higher latitudes or there is an incredible greenhouse gas effect (with a 5% fainter sun in that time) or the paleomagnetologists made a small error in their presumption of fixing all the paleomagnetic poles on the geographic pole for the tectonic movement reconstructions. They claim that this is backed by paleontologic and palynologic evidence. Well, not really, as Ellismere Island tells us. Moreover the magnetic pole is a real swerver and every time when lava gets below the curie point, the pole is somewhere else. You just cannot base paleo-geography on that. So, it’s likely that the assumption about a fixed pole is not entirely correct. I spoke with a young PhD whose thesis was about True Polar Wander, when the inertia tensor of the Earth is not aligned with the spin axis a wandering movement of the poles of a few centimetres per year is possible (max 50cm) So in the 150 million years that it took to change Pangea into the PETM the orientation of the poles could have walked around randomly for 1500 kilometers for every centimetre per year. So despite current paradigms the North may have not exactly been the North 60 million years ago and the area may have been on moderate latitudes. Another factor, how much time do we get to evaporate the ocean? The Beringia bridge closed early in the Tertiary say 120 Million years ago. The Western American passage dried up half way to the Paleogene. The Atlantic remained closed by the De Geer Land Bridge and probably by the Thulean land bridge between Iceland and Europe. There are multiple signs of migration across the Turgai strait in the Paleocene. So when was isolation 100%? 80 - 65 – 50 million years ago? How many million years do you need to lower sea levels around one kilometre? One millimetre a year would be one million years. But I have a few dozen million years available. But the Azolla (Duckweed) on the Lomonosov Ridge 49 Million years ago still provides an essential key for the PETM. (The Brinkhuis study in Nature) Look here for the Lomonosov Ridge: http://www.ecord.org/exp/acex/prel14.html Duckweed does not grow in salt water and on large fresh water surfaces. You will not find it on larger lakes only on still ponds. If those are really in situ as the authors claim, then there is only one logical explanation. The Lomonosov Ridge was emerged above sea level 49 million years ago to have some still ponds where duckweed can thrive. So goodbye Malcolm McKenna, we don't need a fresh water Lake Arctica, only an emerged Lomonosov Ridge. But the tectonic movements have probably been very complicated before and after the PETM, I can imagine a scenario with compression, subduction and uplift and rifting that made the Lomonosov ridge make some strong vertical movements in the course of those two hundred million years. But I think we need a tectonic expert to discuss the feasibility of that solution. Finally, we can disagree about what has happened but is clear that the many data and inputs are so complex and contradictory that it’s an excellent opportunity to unleash the scientific method in its purest form. Formulate and test the hypothesis by logical predictions. That’s a very rare thing in geology. We will modify the steps and it will probably not be the last time.
One more thing about: But the essential thing is to explain the new facts, unknown at that time, that is tropical algaes in the sediment core of the Arctic. Now if we don't believe the vision in Nature that the Arctic was a tropical swimming pool once we need to find a common down to earth mechanisms, to challenge that. So the basic assumption is strong inflow of tropical waters to the Arctic to explain that. A flow the other way around would not help unexplaining the tropical swimming paradise, obviously.
here are 10 new steps: 1. At the break up of the PETM 200 million years ago the North American continent starts to move and rotate away from Europa, Alaska moving towards Beringia in Asia, Labrador and Greenland stay connected to Europe via the Van Geer bridge in the North. 2. The rotation causes compression strain on the deep Arctic basin which causes the Lomonosov Ridge to form as a wrinkling up. 3. Eventually a complete hydrological isolation of the Arctic Ocean occurs after the break up of Pangaea before the PETM somewhere around the Cretaceous 80-120 million years ago, the Lomonosov ridge is now close to the maximum height, perhaps just below global sea level. 4. Considerable local sea level lowering in the Arctic in the isolation phase due to evaporation and/or tectonic volume changes until the end of the Paleocene, 55 Million years ago. 5. Breaching of one of the water channels reconnecting the global ocean to the Arctic at the onset of the PETM event, triggering the chain of events 6. Refilling of the Arctic basin with warm ocean water along with alien biota (Apectodinium) however at this point the Lomonosov ridge remains above sea level. 7. The transport of water to the Arctic causes sea level lowering, triggering global-scale clathrate destabilization. But perhaps not Eustatic (world wide) perhaps only the Tethys sea initially (was it isolated?) 8. Strongly enhanced ocean currents, propelled by the methane gas bubble streams, changed climate, transporting equatorial warmth to colder latitudes causing a moist warm climate. 9 The Lomonosov landbridge ridge thrives and produces lots of Duckweed. 10 The tectonic break up and spreading of the Atlantic causes heavy rifting in the Arctic and the Lomonosov ridge subiding quickly to the present depth Nobody said that it was going to be easy and I wonder about Occam Razor
For the record (and for Andre if he looks here before checking his Emails): A few minutes ago I mailed to Andre's friend (and Andre) the following summary of my "bottom up" idea as the "trigger for the clathrate gun." (However here, by edit, I have corrected a few very minor typos, and may correct more if I notice them.) My “Bottom Up” idea, and its physics: Thermal conductivity of clathrate is remarkable low for a crystal. There is net heat flux outward from Earth‘s interior. Deep ocean water is normally two, or less, degrees Celsius, but if a “clathrate blanket” is on the bottom, there must be a higher temperature, T, at the dirt/clathrate interface to make a thermal gradient required to transport this “internal source heat” thru the clathrate blanket. Thus, at some thickness of that blanket, the Clathrate at the dirt/clathrate interface will be come unstable. When this happens the newly formed water, probably with dissolved methane, not bubbles, because of the pressure, will have drastically increased heat transport ability because the dominate heat transport process is now convection. The interface between this “just formed” bottom water and the still crystalline clathrate blanket above it is at slightly less pressure than the clathrate that has just decomposed to form this bottom water. Hence it is less stable and essentially at temperature T also, so it rapidly decomposes also. I.e. Once it starts at the very bottom of the clathrate blanket, convective heat transport rapidly eats away the bottom of the clathrate blanket, until this warmer* bottom water breaks thru the blanket. This bottom water, which was trapped by the blanket may not be quite as hot as T, when it breaks thru the blanket, but is should be warmer* than the bottom water that was on top of the blanket, so a Taylor instability rapidly transports the methane rich bottom water to the ocean surface / atmosphere with little time for the methane to diffuse/dissolve in other ocean water. You know the rest of the climate change story, much better than I do. I am only filling in a mechanistic detail of how sudden drastic global warming starts and continues globally due to the positive feed back**. I.e. I think I have discovered the trigger of the “clathrate gun.” I do want to note that this mechanism is effectively a long-period clock, which sets the period between ice ages. It is not a very good clock with a constant “tick period,” but that is what is observed for the interval between ice ages. Until now, I never accepted any of the explanations for how the Earth escapes from an ice age when the albedo of ice and snow is so high. I think I know how now. Ironically, a couple of years ago I wrote a book called Dark Visitor with subtitle “the coming ice age," but the ice age of that book has a unique cause, which is physically possible, but very unlikely. I wrote book because of my concern that too few westerner students are interested in science and the West will lose scientific leadership to the Orient during the coming generation. More information about that at www.DarkVisitor.com if you are interested. Please let me know what you think of my “bottom up” idea and keep Andre in the Email loop. Thanks {real name given here}, alias “Billy T” at www.sciforums.com where I met Andre and as book’s author. ------------------------------------------------- *I do not know the heat of fusion of clathrate or the time scale of the “eat thru” process during which more heat from the dirt enters the newly formed bottom water. Perhaps the convection even agitates the dirt and exposes hotter dirt. These details would be complex, but I am reasonable confident that the Taylor instability will develop, and accelerate as some of the methane comes out of solution making bubbles. **Here I am referring not only to the general global warming by greenhouse effect of the released methane, but perhaps more importantly, and certainly more rapidly, to the fact that the rapidly rising column of water with methane bubbles in it is a “pump” driving convective cells in the ocean that may bring warmer than 2 degree water in contact with the top of the clathrate blanket in other locations, perhaps even physically transporting other clathrate to locations where it too is unstable.
Except for the fact that it may have been moved around some, I think there is good data on the orientation of the Earth’s magnetic field vs. time (many reversals) recorded in the rocks of the mid-Atlantic spreading. This data is to the tectonic plate theory the same way that the cosmic microwave background radiation data is to the big bang theory. I.e. in both cases, despite T. Kuhn’s observations, the new data caused a rapid transformation in the accepted scientific model. (People posting here who want to replace the existing models please note that doing so is possible, but reproducible data, not pet ideas, is required.) Perhaps the temporal resolution of this data is not adequate to give details on what happened during the last 60million years. I am very confused about the various times things happened once you start talking about any thing before two days ago. Please Register or Log in to view the hidden image! (and all the names you historical geologists / biological paleontologists invent does not help me straighten it all out, even if I were to try. For example, I half understood your paragraph that led to the Lomonosov Ridge, but by then I was totally lost.) Please Register or Log in to view the hidden image! I too do not believe that solar heating made a "tropical swimming pool" near the spin axis pole (assuming it was near there back then) so I think that your point here is well taken; however, the low angle of incidence and long period of total absence of sunlight at and near the polar spin axis both helps and hurts your Big Niagara theory. What you note here is the "help." What I noted as objection to a "dry basin" for Big Niagara to fall into is the “hurt.” Perhaps an alternative to consider, if the circum-polar atmospheric currents did keep the polar air mass distinct, is that prior to "Big Niagara" there was a large cold Lake Arctica with a mile or so thick clathrate on the bottom (despite my bottom up mechanism)* and then "large", but not "big," Niagara happened with the connection of the higher ocean to the lower Lake Arctica. The influx bringing the tropical biota and starting a "top down" self accelerating release of methane, which remained relatively polar because of the circum-polar currents? Note that methane may absorbe sunlight passing over the pole and reradiate it downward much better than linear symetric molecules like oxygen and nitrogen. (I think methane is non polar, unlike CO2 which is polar, so perhaps only its extra vibrational modes is why it is a more effective green house gas - I.e. this "methane downwards radiation may not be significant, except for the sun's IR radiation.) (I am also just guessing that CO2 is not linear as O-C-O because the diamond and graphite structures indicate that the "binding orbitals" L. Pauling described are not at 180 degrees to each other. Once I knew the facts about all this, but that was long ago.) My bottom up mechanism could not play any role in this because of the increased pressure of the "Large Niagara" water on top. That pressure makes even a "top down" triggered decomposition very questionable, but as the influx is salty it may have been more dense despite its higher temperature and spread out on top of the "mile thick" clathrate. - All just wild guessing for you to think about. Also if there was only "large niagara" you may need to accept part of the (I think) more standard explanation for the tropical biota found in the arctic cores. I.e. agree that ocean currents, such as the gulf stream, do transport this biota north of it origins before it decomposes, but only to high latitudes. I.e claim that "large Niagra" drops this biota into the below sea level polar basin lake. I will read your “ten new steps” post and get back to you with comments, if I have any, after posting this. ------------------------------------- *I know nothing about it, perhaps no one does, but I bet some oil searchers do, but I can easilly accept as true the idea that the iron core etc is much more non spherical than the surface of the Earth due to the spin of the Earth. Hence the bottom up heat flux may be much less at the spin poles than at the equator.
Ok - I have now read your new 10. Not much to say except you seem to be drifting to what I called "large" but not "big" Niagara now. On (7): Hell, lets go for "Eustatic." (I did not even know that word five minutes ago, but it has a nice ring to it.) Why? Here is why: Your (and others) drop in surface levels of "southern oceans" triggers "top down" and general volumetric* decomposition. Your "large" Niagara in flux with my observation that this inflow of salty warmer water may be dense enough to "bottom flow" can decompose the clathrate on the bottom of Lake Arctia. ------------------- *aided by the thermal gradient of my "bottom up" mechanism.
I've looked over the shoulders of the people who invented those theories long enough to recognize the begging-the-question and affirming-the-consequent fallacies. Sediment cores are measured exactly on three-dimensional magnetic susceptibility. The horizontal direction obviously points towards the magnetic pole, the angle of incidence says something about the distance to the pole. Moreover if you have more proxies you can construct the triangle and find the pole. This is however depending on a lot of assumptions. 1: as said the magnetic pole to be identical to the geographic pole 2: declination zero but you can see here the large excursion changing on centennial scale. 3. No change in orientation of the sample between magnetic registration and recovery. But sediments twist, turn, tilt, fold etc adding a multitude of unknown variables. So the best you could say that paleomagnetic reconstruction is our best guess about the tectonic movements but there must be margins for improvements should more data become available to cross check. So if the paleo magnetic reconstruction puts Antarctica on the South Pole some 66 Mya: Please Register or Log in to view the hidden image! but at the same time there have been forests over there: http://www.aad.gov.au/default.asp?casid=1680 Francis, J.E. 1991. The palaeoclimatic significance of Cretaceous and Tertiary fossil forests of the Antarctic Peninsula. In: Thomson, M.R.A., Crame, J.A. and Thomson, J.W. Geological Evolution of Antarctica, Cambridge University Press. 623-628. then you might wonder if this is a case of magic or some all to inaccurate assumptions. As for greenhouse effect or not, it’s very hard to believe that there could be forests on a ice cap free South Pole even if the temperatures were 10 or 20 degrees higher. So it appear that there is little incentive to really really test paleo magnetic tectotonic assumptions to hard geologic proxy evidence. Anyway I guess we still have to destabilize the clathrate in the big ocean to give Antarctica what it had: a extreme warming at the PETM: http://geology.geoscienceworld.org/cgi/content/abstract/22/3/211 Not me, I’m a retired fighter pilot Please Register or Log in to view the hidden image! But I think you’d really need to read and understand the three Nature studies Here is one of them: http://www.es.ucl.ac.uk/people/m-kaminski/reprints-pdfs/nature04800.pdf You’ll get the other two eventually of Henk Brinkhuis et al (duckweed) and Appy Sluijs (tropical algae)
Thanks again for the reference. I have only started (couple of pages) to read the one of three you recommend I should read, but it is good and I will get back to it. I know very little about paleomagnitism*, but recall seeing a symetrical reversl pattern of roughly equal width strip on both sides of the Mid Atlantic spreading zone that gave me the impression that not too much "twisting and turning" had occured. I would not but too much faith in the weak field records of sediments, but the fileds recorded (in rocks?) cooling below their curry point seem to me to be reasionably valid records of the field strength, if not the direction at time material became magnetic again. I do not even know what "chemical residue magnitic records are. Do you? I.e. do some chemical compounds only form in magnetic fields of some strength or what? Not much on point but there is a worm that lives in the bottom mud of the ocean floor that has magnetic field sense (built on magnitite incorporated in its body I think) They use this information to quickly swim back into the saftey of the mud when some fish has stired it up trying to eat them. The ones in the N. hemisphere swim in the opposite direction along the field lines than those in the southern hemisphere. In a lab dish with coil around it you can you can make them swim up or down by reversing the current. Perhaps some one should look for their fossils? or deposites of their magnitite? - I think not as once safe back inside the mud, they probably do not care about keeping field alignement. I am sort of losing interest in my "bottom up" idea,because I now think that photo of white clathrate I saw is atypical. I think most is mixed in with the silt and may not serve as a blanket any more that the silt does, may not be a well defined interface between clathrate and bottom dirt etc. but now I am mildly interested in PETM and very happy to know at least roughly how the ice ages can end. That question is now on my "who cares" list instead of my "Damned if I know" mystery list. Please Register or Log in to view the hidden image! -------------------------------------------- *I also recal reading that the last fires some primitive people made helped record the magnetic fields at their locations as they cooled.
About the sea floor spreeading and magnetic orientation strips, it appears that an insider here has some considerations. http://www.scientificexploration.org/jse/articles/pdf/15.4_smoot.pdf But I can't reallly judge it's merits. Nevertheless it appears quite impossible for me to have warm polar regions in the polar areas during the paleocene and that a circular reasoning can be identified: we assume that the poles were on the poles .... consequently the poles are on the poles. An alternative of course is an extreme obliquity of the spin axis, causing warm summers but also very cold winters. But how feasible would that be?
