I have nothing to apologize for, you're the one making the wrong assertions.
A Note: Global Warming Threads
- Thread starter Tristan
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I have nothing to apologize for, you're the one making the wrong assertions.
Why yes the links DO support it.
Source IPCC TAR WG1
So the IPCC says even if it gets far warmer than any plausible sceneario of climate change, there will STILL be ice in Antarctica for the next 10,000+ years, then CLEARLY there is ZERO PROBABILITY of us reaching Venus like conditions in the next several hundred years.
ZERO.
Indeed we DO have some various numbers that would help us prove that, and one of them is that over the last ~40 years, the oceans have warmed ~0.04 C, on average from 0 to 3,000 meters.
When you try to figure out how much additional heating will be needed to boil the oceans just consider that ~90% of the total volume of ocean is between 0-3 degrees Celsius.
But I'm willing to be reasonable.
Simply find ONE reputable scientific publication that states that we could become somewhat like Venus in any time frame less than 10,000 years and I'll admit that you are right.
Yes because if you claim this massive disaster is going to happen and you are proved wrong then people are likely not to pay attention to other bad, but more reasonable, predictions.
Irony.
If you admit the Clathrate Gun Hypothesis.
And if you admit the Clathrate Gun Hypothesis as the cause of the extinction at the end of the Permian.
Then you must also admit that the catastrophic release of clathrate is incapable of pushing the Earth into a Venus like state.
The proof is obvious.
If you admit the Clathrate Gun Hypothesis.
And if you admit the Clathrate Gun Hypothesis as the cause of the extinction at the end of the Permian.
Then you must also admit that the catastrophic release of clathrate is incapable of pushing the Earth into a Venus like state.
The proof is obvious.
Find one post from me in which I argue for that, or even sillier claim it is "going to happen", and I will reevaluate my assessment of your agenda here as primarily deceptive;adoucette said:
with consistency: misreading and misattributing me and everyone you respond to here in a pattern.
(btw: anyone focused on intellectual dishonesty would of course have picked up on that immediately - many pages ago. And responded appropriately.)
Meanwhile, the issue of a potential positive methane feedback loop touched off by CO2 warming at high latitudes - the issue I've been posting about the last few pages here - any thoughts?
Another cryptic post, apparently responding but to nobody visible.trippy said:
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Certainly it is obvious that in the past the Earth has not switched to its hot STABLE state. Thus, if it were to do so, it would be because something is happing which has never happened before. Significantly higher than present levels of CO2 have existed in the past so that alone will not cause the switch. The only thing that is "first time ever" is the rate of CO2 increase caused by man's burning of fossil fuels.
The rate of CO2 release being more than every before means the rate of global warming is greater than ever before and that in turn means the rate of CH4 release from land based stores, at least, is greater than ever before. There is also strong indication (in the bubbling up of CH4 in shallow Arctic waters) that in these shallow waters there is CH4 being released into the atmosphere which was not occurring a decade ago - USSR's sub were based there as it was from there they would fire ICBMs over Canada at the US in their part of MAD policy of the time. Only in the last decade have the CH4 bubble clouds made it difficult or impossible for their sonars to work.
Whether or not these "never happened before" phenomena do make (or lead to) a positive feedback system with loop gain greater than 1 so it feeds on its self and grows until some saturation effect reduces the loop gain to unity is a question that CAN NOT BE ANSWERED BY APPEALS TO HISTORY as it has never happened before. Thinking that it can be dismissed by "well it did not happen before" is wishful thinking not a scientific approach.
To answer the question, one must build some models that include these new (less than decade old) phenomena. Thus appeals to models that do not for example consider that the more rapid CH4 release may reduce the tropospheric, especially in the lower levels,* concentration of OH radical and thus increase the half life against destruction of CH4 are also useless wishful thinking and not a scientific approach.
AFAIK, there is no model that does consider any mechanism in which the life time of CH4 is a variable that is increasing as the OH radical concentration in the lower troposphere is reduced (four OHs converted to H2O for every extra CH4 introduced into the lower troposphere with tiny increase in the life time of other CH4s by the removal of those four OHs.)
It seems essential to me, if one want to be scientific, to build such a model, even a crude one is better than none. It seems, however, many posting here would rather stick with "wishful thinking" and "It has not happened before" than a scientific attempt to answer what MAY be a very important question.
I suggested part of such a model in post 658 asking for comments etc. but there seems to be no interest in the type of model needed - "Wishful Thinking" and "It never happened before." is much easier and more satisfying.
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*As the OH radical is only formed high in the stratosphere by harsh UV splitting of H2O, any reduction in OH concentrations will be most pronounced in the lower levels of the troposphere first. The crude model I suggested in post 658 starts with a linear decrease in OH concentrations from a maximum at the top of the troposphere down to zero at the surface. Then as the surface release of CH4 increases from that of the assumed to be in dynamic equilibrium of the 2000/2005 era, the altitude of the zero OH concentration level moves up from the surface, so there is no destruction of CH4 in the levels below that zero OH level, but a constant CH4 (concentration ?) or at least a constant flux up below that zero OH level, which of course returns more of the IR trying to escape back to the Earth. That leads to greater CH4 release rate from the surface. It is this feedback, which AFAIK is totally absent in the IPCC and other existing models.
I have not had time to read link below, but quick scan of it show is has some useful information, so am now simply recorded it:
http://books.google.com/books?id=Sp...ge&q=the sun is 100 percent efficient&f=false
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I was specifically responding to this post where you claimed that it WAS possible by including in your ending that says the "outside chance" is "still worrying"
iceaura said:
I don't think I misread that.
It seems pretty clear even when re-reading this post that you are in fact claiming that the odds are not zero of a Venusian Catastrophe occuring to the earth because of methane feedback and that this catastrophe could possibly occur within the next couple of hundred years.
To which I responded that over that timeframe it was zero simply because if Antarctica is still going to be around for 10,000 years, in far higher warming conditions anticipated in any scenario of climate change then it is obvious that that kind of change in that kind of time frame is impossible. In a later post, to add substance to that evaluation I gave the amount of actual heating of the oceans over the last ~40 years to put the amount of energy it would take to raise the oceans even ~16 d C in perspective and show that it is something which doesn't have even an outside chance of occurring over those kind of time frames.
iceaura said:
But ice that reply was in response to a totally different question.
You ASKED
iceaura said:
And so in the context of THAT specific question I was answering in general about why hyped up scare stories don't help.
Which is how I read this comment by you: "This extra methane risk is one of them, and maybe the possibility of a Venusian catastrophe makes a reasonable if dramatic touchstone for considering it", "it" being the greenhouse effects of the ongoing CO2 buildup
So yes, given your multiple statements, it certainly appears that you have been saying that a Venus Catastrophe is a possibility, and even as soon as the next couple of hundred years, even if you couch that by saying you think the odds are low.
Which is why I gave you the chance to prove I'm wrong simply by finding a scientific reference from a mainstream source that suggests that we could suffer a Venus like Catastrophe within 10,000 years and if so, then I'd be willing to concede the point.
iceaura said:
Yes, read Trippy's recent links on the subject, the ones I quoted from earlier, they seem to be the most germaine (unfortunately you have to buy what appears to be the most recent on the subject, something that I'm not willing to do)
Arthur
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Which ones?
These ones are all free:
http://geosci.uchicago.edu/~archer/reprints/archer.2007.hydrate_rev.pdf
http://pangea.stanford.edu/research/Oceans/GES205/methaneGeology.pdf
http://geosci.uchicago.edu/~archer/reprints/archer.2008.tail_implications.pdf
http://geosci.uchicago.edu/~archer/reprints/montenegro.2007.fate_CO2.pdf
This one has some links of interest, including to an interactive climate model:
http://geoflop.uchicago.edu/forecast/docs/
Neither is this a scientific approach, Billy.
Have you bothered to look at any of the links i've posted?
Wrong. Models do take it into account.
http://downloads.climatescience.gov/sap/sap3-4/sap3-4-final-report-ch5.pdf
Up until recently, measurements of atmospheric Hydroxyl variablity have been highly variable. They've been highly variable because they've used a proxy - Cholormethane (IIRC), so there's been some uncertainty whether the variability in chloromethane was because of variability in manufacture rates or destruction rates, however, with the institution of the Montreal protocol production has dropped to zero, and it turns out that the variability in the levels of hydroxyl radicals in the atmospher is a lot less than previously indicated.
http://newscenter.lbl.gov/feature-s...s-on-the-threshold-of-abrupt-climate-changes/
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Oh yeah.
And this is blatantly wrong as well.
The Chemistry actually looks like this:
CH[sub]4[/sub] + HO[sup].[/sup] -> H[sub]3[/sub]C[sup].[/sup] + H[sub]2[/sub]O
H[sub]3[/sub]C[sup].[/sup] + O[sub]2[/sub] -> H[sub]3[/sub]COO[sup].[/sup]
From there there are several possible reactions that result in the production of Formaldehyde, which oxidizes to Carbon Dioxide after about 5-8 hours in sunlight.
So does that mean that your concerns are now reduced by 75%?
Oh right.
http://downloads.climatescience.gov/sap/sap3-4/sap3-4-final-report-ch5.pdf
Probably has some (or many) of the same things to say.
Thanks for the link. I have not time to read it all now but the last of the summary "key findings" states:
"However, it is very likely that climate change will accelerate the pace of chronic emissions from both hydrate sources and wetlands. The magnitude of these releases is difficult to estimate with existing data. Methane release from the hydrate reservoir will likely have a significant influence on global warming over the next 1,000 to 100,000 years. ...''
I was not stating that CH4 release has not been considered nor that various FIXED rates for it have not been considered. I was asserting, mainly from a base of ignorant guessing about the models that they did not include the positive feedback in the model. I.e. that as the release increases the the lifetime of CH4, especially in the lower troposphere, there is more IR returned to the surface which then can increase the release rate of CH4.
If that is included in the model(s) your link is discussing and you know the page number were that is mentioned, please give it, and I will retract my statement that AFAIK no models include this positive feedback.
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I now have had time to skim your second post 670 link and find:
"The IMPACTS team will initially focus on four types of ACC:
1) instability among marine ice sheets, particularly the West Antarctic ice sheet;
2) positive feedback mechanisms in subarctic forests and arctic ecosystems, leading to rapid methane release or large-scale changes in the surface energy balance;
3) destabilization of methane hydrates (vast deposits of methane gas caged in water ice), particularly in the Arctic Ocean; and
4) feedback between biosphere and atmosphere that could lead to megadroughts in North America.
Only half joking, Collins refers to these as “the Four Horsemen of the Apocalypse.” ..."
So it does look like what I am concerned about WILL be considered. I.e.point (2) which I made bold.
BTW, I am not much concerned by point (3) as the methane hydrates are all below at least 300m of water which is at least 4C or colder. Points (1) and (4) could be hellishly hard on near sea level cities or farmers, even make mass starvations, but humanity would survive, which it would not if Earth were to become more Venus like.
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thanks again. Yes. My concerns were not very large to start with as currently only about 2% of the CH4 release is coming from cold storage CH4. Thus there would need to be a huge increase achieved by the positive feed back loop to drive the switch to the hot stable state. Positive feedback systems can do strange things, even from tiny starts* - that is why I think they need to be included in the models. To know what level they can grow to, you need to have some understanding of what causes their growth to cease - I.e. what is the saturation mechanism.* The obvious one in this case is that the cold stored CH4 is finite. One can not dump more than all of it.
Furthermore all of it has probably been dumped in the past but slowing enough that the destruction by chemistry you state keeps the CH4 atmospheric concentration relatively unimportant in the global warming picture. As I have made very clear in all my post on this remote possibility, it is the "first time ever" extremely rapid increase in CO2 released by fossil fuel use that is making the release of CH4 more rapid from cold storage than ever before, perhaps leading to an increase in CH4's atmospheric lifetime, which could be a feedback system with rapidly growing gain.
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* For example, as most have experienced, inaudible thermal noise can rapidly grow with positive feedback into an ear-splitting scream the volume of which is limited by the power of the audio amplifier – that is the “saturation limit" of this example.
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Just to dirve the point home a little more Billy, and Iceaura.
The (apparent) assumption that the rate of production of OH[sup}.[/sup] is constant is fundamentally flawed.
Hydroxyl radicals are not produced directly by the photolysis of water, they are instead produced by reactions between Ozone and water, so the rate of production of Hydroxyl radicals is dependent on the amount of water in the atmosphere - which will increase with increasing temperature, and the amount of Ozone in the atmosphere.
Also, I would like to point out that in some regards, some of the reactions of methane ion the atmosphere are catalytic WRT OH[sup].[/sup] production.
From: http://www.atmosp.physics.utoronto.ca/people/loic/chemistry.html
Which, incidentaly, provides a potential mechanism to explain Arthurs point regarding the apparent flatness of the Methane concentration graphs - namely that the above chemistry suggests some capacity for the atmosphere to behave in a similar manner to a buffering solution and smooth out changes of methane on timescales longer than about a year or two, and in order for the bulk concentration to change, the amount added, or the rate at which it's being added have to exceed a certain threshold before any changes can occur (the threshold being sensitive to the reaction rates involving HO[sup].[/sup] and NO[sub]x[/sub] as well as competing reactions with other trace gasses).
The (apparent) assumption that the rate of production of OH[sup}.[/sup] is constant is fundamentally flawed.
Hydroxyl radicals are not produced directly by the photolysis of water, they are instead produced by reactions between Ozone and water, so the rate of production of Hydroxyl radicals is dependent on the amount of water in the atmosphere - which will increase with increasing temperature, and the amount of Ozone in the atmosphere.
Also, I would like to point out that in some regards, some of the reactions of methane ion the atmosphere are catalytic WRT OH[sup].[/sup] production.
From: http://www.atmosp.physics.utoronto.ca/people/loic/chemistry.html
Which, incidentaly, provides a potential mechanism to explain Arthurs point regarding the apparent flatness of the Methane concentration graphs - namely that the above chemistry suggests some capacity for the atmosphere to behave in a similar manner to a buffering solution and smooth out changes of methane on timescales longer than about a year or two, and in order for the bulk concentration to change, the amount added, or the rate at which it's being added have to exceed a certain threshold before any changes can occur (the threshold being sensitive to the reaction rates involving HO[sup].[/sup] and NO[sub]x[/sub] as well as competing reactions with other trace gasses).
I don't understand your chemistry so will not argue against it, but this "smooth out changes of methane on timescales longer than about a year or two," does seem strange (inconsistent?) with the very clear, regular, annual oscillations in the CH4 concentration curves. Are you saying that the amplitude of these oscillations would have been much greater, except for the effect you are describing?
No.
What I'm suggesting is that the buffering takes time because the methane reacts relatively slowly with the Hydroxyl radicals, and that because of this, the seasonal variability may be occuring on time scales quicker than the buffering provided by the atmosphere can adjust.
This is where the analogy with acid-base buffering falls over, because acid base chemistry is pretty much instant, where Methane has a half life measured in years.
I would wager looking at that graph, incidentaly, that seasonal variability of Methane may have more to do with Methane destruction, than Methane production.
Sure. So I pointed out the obvious (in the service of another claim entirely) and you responded with irrelevance - what does the lifespan of the Antarctic ice sheet have to do with it?adoucette said:
Your very own links are (admirably) specific in their reliance on various assumptions, which makes their conclusions probabilities. Now this is of course a meaningless truism in many cases - nothing is certain in the physical sciences, by definition - but in the case of the Venusian catastrophe the assumptions are actually uncertain. It is not at all certain, for example, that the entire ocean has to be heated uniformly to its nether depths in order to release enough methane to create that catastrophe. There are other factors involved - changes in currents, the exact geography of the deposits, release of ice pressure and isostatic rise, some possible but ordinary bad luck with volcanoes and earthquakes and even smaller meteors, etc, a fairly long list.adoucette said:
Which ordinary provision of small doubt is not my argument - merely my assumption, which I think is not genuinely arguable given the language of your links ("presumably would be gradual" about the melting due to gradual warming via CO2, etc).
My argument is that a shorter term (say ten years to a new equilibrium, methane's lifespan according to the links), plateaued, positive feedback "bump" in the methane concentration would be something that might easily happen, given what we can see from our discussion of the Venusian catastrophe if no other discussion is going to be recognized (the apparent case, for some reason), and something that might easily cause what ordinary people would term a "disaster" lasting centuries.
And - the main point - the factor creating the risk of touching this off would be the continuing and permitted anthro boosting of CO2 concentration.
Once again includign me in these conversations you are having with yourself?trippy said:
OK: your point there simply advances a mechanism by which the new plateau would be established - the oxidation of the methane itself producing some water at the appropriate altitudes and curbing its own further increase, etc.
But a methane greenhouse "disaster" - from the increased water vapor assumed, the extra CO2 produced, the boosted methane concentration established, and so forth - is a real and present concern: correct?
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The study showed two things:
How long it would take, at +20C to do away with the East Antactica Ice Sheet, 10,000+ years, so that gives us a reasonable scale of the amount of time that a HUGE amount of heating of the planet would take to just melt the existing ice on the planet.
And the reference that a global temp rise of +20C was far greater than any plausible climatic change.
So given both of those facts, the conclusion it quite simple, changes that would resemble in any way the Venusian Catastrophe, could not possibly happen in several hundred years.
As I said, find a reputable scientific study that shows it could occur in 10,000 years and I'll concede the point, otherwise, discussions of a potential Venusian Catastrophe on Earth happening within even a millenia, are not relevant to discussions of actual issues based on climate change.
Arthur