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Post by socold on Nov 26, 2010 1:03:27 GMT
Part of the myth of AGW is the failure to see the dynamic of a spinning globe alternately warming & cooling. GCMs have a spinning globe alternatively warming and cooling...
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Post by socold on Nov 26, 2010 1:09:02 GMT
I'm sure most climate scientists would take with a large pinch of salt any result from modelling of the earth with conditions so far out of anything we've measured. There's no religiously inspired *need* for CO2 to be all important. Then explain the bogus science article on how the greenhouse effect would collapse without non-condensating GHG? Because without non-condensating GHGs the atmosphere would be sufficiently cooler meaning the condensating greenhouse gas water vapor would also reduce. The atmsphere would be colder without CO2, CH4, etc. Cooler atmosphere, less water vapor. Less water vapor, cooler atmosphere still. You'd end up at a point with a much colder atmosphere than today with less water vapor than today, and ice covering much of the surface of the Earth.
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Post by af4ex on Nov 26, 2010 2:58:25 GMT
socold> 1) The atmsphere would be colder without CO2, CH4, etc. > 2) Cooler atmosphere, less water vapor. > 3) Less water vapor, cooler atmosphere still. Your third proposition seems to contradict the second. If less water vapor meaning less warming, then you acknowledge that water vapor warms the atmosphere. But if that's true then water vapor reverses the second proposition, preempting the "cooler atmosphere". This water vapor warming must be happening because the Mar Greenhouse shows that CO2 has very weak GH warming effect, nullifying your first proposition. CO2 seems to be the weak link here, because you "need" a significant GH warming effect to prime your positive water vapor feedback. But the evidence from Mars says the CO2 GH warming is weak.
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Post by steve on Nov 26, 2010 11:36:37 GMT
The weakness or strength of the link is irrelevant if there is a link.
There is perhaps a tipping point between there being enough warmth to maintain comfortable temperatures (ie. not snowball earth) and too little warmth such that water vapour condenses out and temperatures collapse resulting in much of the earth being ice covered. In such a scenario there is less water vapour but there is also less sunlight being absorbed.
If temperatures collapse, CO2 by itself needs to do a lot more work to lift temperatures to the tipping point where the hydrological cycle gets going. Once it gets going sufficiently then Whoomph! Water vapour-related and albedo related feedbacks rapidly warm to comfortable temperatures.
Fortunately, a frozen earth does not prevent volcanic emission of CO2, but does prevent CO2 being washed out of the atmosphere. So as long as the earth is volcanic, CO2 can act to keep earth from being permanently frozen because however "weak" the effect it can simply build up and build up to as many ppm as is necessary.
That CO2 causes less of the current greenhouse effect than water vapour is not in question. But it is not "bogus", as Icefisher suggests, to question whether and in what circumstances water vapour by itself could lift earth out of a deep freeze.
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Post by icefisher on Nov 26, 2010 14:50:41 GMT
Because without non-condensating GHGs the atmosphere would be sufficiently cooler meaning the condensating greenhouse gas water vapor would also reduce. The atmsphere would be colder without CO2, CH4, etc. Cooler atmosphere, less water vapor. Less water vapor, cooler atmosphere still. You'd end up at a point with a much colder atmosphere than today with less water vapor than today, and ice covering much of the surface of the Earth. That is just repeating the claim Socold without providing any form of explanation. It is reasonable to assume perhaps that it would be somewhat cooler but there is zero evidence that the greenhouse would collapse. So Socold you need to show us not tell us why the small amount of non-condensating GHG is important. Telling us the solution was run through a black box calculator will not be a satisfactory answer.
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Post by steve on Nov 26, 2010 16:05:48 GMT
Isn't the evidence for snowball earth periods non-zero evidence that the hydrological cycle could not prevent the planet from almost freezing?
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Post by icefisher on Nov 26, 2010 22:18:48 GMT
. The weakness or strength of the link is irrelevant if there is a link.
There is perhaps a tipping point between there being enough warmth to maintain comfortable temperatures (ie. not snowball earth) and too little warmth such that water vapour condenses out and temperatures collapse resulting in much of the earth being ice covered. In such a scenario there is less water vapour but there is also less sunlight being absorbed.Perhaps? Thats pure guessing Steve! More likely since regions of the earth straddle the line on how much sunlight is sufficient to melt ice without any greenhouse effect is a process that wind circulation patterns that cover sometimes more than a couple of thousand miles continually distributes water vapor across the entire globe. Upper air patterns are constantly moving up to 100 miles an hour and water vapor can stay aloft for days. This is a concept that strong positive feedback punches a bigger hole the theory. It is a lot less likely you could have a partial greenhouse collapse when you have high positive temperature feedbacks. Complete greenhouse collapse with high positive feedbacks is just completely irrational. If you have no clouds and no water vapor in the tropics evaporation is going to accelerate dramatically with triple feedbacks and circulation patterns are going to carry this moisture to the poles. Most like how Schmidt did it was parameterize a model with static clouds with insolation held at the level of present day cloud coverage and then subtract warming from CO2 with the assumption that high feedbacks from that controls most of the water vapor. Another Schmidt brain-dead thought experiment if you ask me and you gobble it up like a cod on a clam. If temperatures collapse, CO2 by itself needs to do a lot more work to lift temperatures to the tipping point where the hydrological cycle gets going. Once it gets going sufficiently then Whoomph! Water vapour-related and albedo related feedbacks rapidly warm to comfortable temperatures.
Fortunately, a frozen earth does not prevent volcanic emission of CO2, but does prevent CO2 being washed out of the atmosphere. So as long as the earth is volcanic, CO2 can act to keep earth from being permanently frozen because however "weak" the effect it can simply build up and build up to as many ppm as is necessary.
That CO2 causes less of the current greenhouse effect than water vapour is not in question. But it is not "bogus", as Icefisher suggests, to question whether and in what circumstances water vapour by itself could lift earth out of a deep freeze. I would suggest Steve that the loss of a global average cloud albedo all by itself would provide sufficient wattage to do a lot more than CO2 does. Where your model goes completely wrong is with a zero greenhouse effect ice will melt anywhere on earth that insolation is less than about 315watts. . . . which is nowhere full time. . . .and without moisture in the air there will be no way to maintain high albedos. Bottom line is the theory you need a non-condensing GHG to get water to evaporate is completely unsupported by any evidence what so ever. Sure you can make a model do it especially a model that holds net solar insolation to a static cloud figure as all the GCMs presently do. What will clouds be made of Steve in there is no water vapor in the sky? Clouds reflect 77 watts which is a lot more than the total of CO2 absorption.
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Post by socold on Nov 26, 2010 22:31:47 GMT
socold> 1) The atmsphere would be colder without CO2, CH4, etc. > 2) Cooler atmosphere, less water vapor. > 3) Less water vapor, cooler atmosphere still. Your third proposition seems to contradict the second. If less water vapor meaning less warming, then you acknowledge that water vapor warms the atmosphere. But if that's true then water vapor reverses the second proposition, preempting the "cooler atmosphere". That would only be true if I claimed water vapor was the only thing that warmed the atmosphere.
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Post by socold on Nov 26, 2010 22:35:53 GMT
Because without non-condensating GHGs the atmosphere would be sufficiently cooler meaning the condensating greenhouse gas water vapor would also reduce. The atmsphere would be colder without CO2, CH4, etc. Cooler atmosphere, less water vapor. Less water vapor, cooler atmosphere still. You'd end up at a point with a much colder atmosphere than today with less water vapor than today, and ice covering much of the surface of the Earth. That is just repeating the claim Socold without providing any form of explanation. It is an explaination. I explain why removal of non-condensing greenhouse gases would lead to additional warming from a subsequent fall in water vapor. Water vapor is a greenhouse gas. If water vapor levels fall, there is a cooling effect. It is a satisfactory answer, you are just in denial about it.
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Post by socold on Nov 26, 2010 22:43:24 GMT
If you have no clouds and no water vapor in the tropics evaporation is going to accelerate dramatically with triple feedbacks and circulation patterns are going to carry this moisture to the poles. Pfff what double standards you have. Here you run some ideas through a black box calculator in your head, which isn't half as good as running things through a numerical model, yet you expect everyone to treat it as fact, while at the same time you dismiss climate models.
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Post by magellan on Nov 26, 2010 23:04:07 GMT
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Post by icefisher on Nov 27, 2010 0:47:11 GMT
Isn't the evidence for snowball earth periods non-zero evidence that the hydrological cycle could not prevent the planet from almost freezing? No it does not provide any credible evidence. Evidence has to be at least likely before it can be considered non-zero. Evidence of snowball earths have not occurred recently enough to rule out unusual causes or misdirective markers (magnetic changes (used to locate glacially deposited rock), vulcanism, meteors, solar variation, and orbit change) to make it likely such an earth condition provides positive non-zero evidence of the power of the hyrological cycle.
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