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Post by steve on May 20, 2009 17:07:47 GMT
I think people in the AGW camp are missing a fundamental issue with ice albedo. Why do you think that? Is it a gut feeling? What would be the localised heating of the arctic ocean in summer with, say, 1 million sq km less ice (equivalent to about 10 years' loss at current rates)? Shouldn't be too hard to work out on the back of an envelop. You might think they stick their fingers into the air and make up numbers, but I expect those that have been asked to do it properly have tried to do a better estimate.
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Post by kiwistonewall on May 20, 2009 17:43:38 GMT
Steve, this has been thrashed out over & over. Low ice in summer doesn't effect albedo by more than a cat's whisker. Reason? Open water steams furiously in summer. When this was discovered, the research team removed their prelim results from the net (I saw them!) and I doubt it was published as too inconvenient.
But other's have reported this.
Result: ZERO. Even I can write zero on the back of a piece of paper.
(It might actually promote cooling, which is a negative feedback)
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Post by socold on May 20, 2009 19:03:11 GMT
Socold _you_ are the one talking about infinity - Hansen only talks about an unstoppable catastrophic runaway to a 'desolate planet'. Which is close to what I actually said that he was stating in my post. A key skeptic argument on this thread has been that if positive feedbacks existed they would cause temperature to continue rising indefinitely. For example when you said: "It doesn't matter how SMALL the positive feedback is - if there are no negative feedbacks the rise in temperature is now totally unstoppable. It will also accelerate on a compounding basis." This aint how it works and isn't what Hansen is saying. Hansen agrees with me that positive feedback in climate causes an amplification of the forcing. So for every 4wm-2 forcing you get about 3C temperature rise. That's it. Max. You don't get more unless you increase the forcing some more. The idea that positive feedback leads to temperature rising until negative feedback cuts in is not using the correct definition of feedback.
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Post by poitsplace on May 20, 2009 20:38:43 GMT
Socold _you_ are the one talking about infinity - Hansen only talks about an unstoppable catastrophic runaway to a 'desolate planet'. Which is close to what I actually said that he was stating in my post. A key skeptic argument on this thread has been that if positive feedbacks existed they would cause temperature to continue rising indefinitely. For example when you said: "It doesn't matter how SMALL the positive feedback is - if there are no negative feedbacks the rise in temperature is now totally unstoppable. It will also accelerate on a compounding basis." This aint how it works and isn't what Hansen is saying. Hansen agrees with me that positive feedback in climate causes an amplification of the forcing. So for every 4wm-2 forcing you get about 3C temperature rise. That's it. Max. You don't get more unless you increase the forcing some more. The idea that positive feedback leads to temperature rising until negative feedback cuts in is not using the correct definition of feedback. LOL, don't you find it odd that hansen's figure falls JUST AT THE EDGE of being possible even theoretically? We're stuck with the same problem though...there's not enough warming. There never has been. Heck, you can't even demonstrate that the warming we've had is from CO2. We REALLY aren't sure why the earth warmed. Also part of the problem with the feedbacks isn't so much that they'd run away forever but that they'd run away until they hit diminishing returns. This is why the concept of strongly positive feedbacks is unlikely. Now solar forcing SEEMS to have some sort of positive feedback but unlike AGW's feedbacks, we can observe that there really is a disproportionate response with solar forcing. The feedbacks proposed for AGW never have panned out. Here we are, we've had all this extra CO2 and the warming is actually coming up SHORT when we're pretty darned sure the earth was ALSO warming up on its own anyway. Sorry, the observations point to neutral to negative feedbacks.
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Post by nautonnier on May 21, 2009 12:26:47 GMT
Socold _you_ are the one talking about infinity - Hansen only talks about an unstoppable catastrophic runaway to a 'desolate planet'. Which is close to what I actually said that he was stating in my post. A key skeptic argument on this thread has been that if positive feedbacks existed they would cause temperature to continue rising indefinitely. For example when you said: "It doesn't matter how SMALL the positive feedback is - if there are no negative feedbacks the rise in temperature is now totally unstoppable. It will also accelerate on a compounding basis." This aint how it works and isn't what Hansen is saying. Hansen agrees with me that positive feedback in climate causes an amplification of the forcing. So for every 4wm-2 forcing you get about 3C temperature rise. That's it. Max. You don't get more unless you increase the forcing some more. The idea that positive feedback leads to temperature rising until negative feedback cuts in is not using the correct definition of feedback. SoCold you are missing the issue - CO 2 is not the only cause of warming by absorption in the atmosphere - in fact the 'feedback' that AGW relies on is water vapor that it is claimed will increase and amplify the 'greenhouse' (sic) effect. That is where you want to stop your argument. However, the water vapor is not sentient and doesn't realize that the warming it has caused is due to its own effect - so it goes on to evaporate more as the atmosphere is warmer causing more positive feedback - and so on - once you get to a certain point _ if there is NO NEGATIVE FEEDBACK_ water vapor could take over all on its own - after all it is hugely more effective as a greenhouse (sic) gas than CO 2 and there is LOTS more of it. Of course the reason this doesn't happen is that there ARE negative feedbacks - that you for some reason do not want to admit to.
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Post by steve on May 21, 2009 13:52:12 GMT
Steve, this has been thrashed out over & over. Low ice in summer doesn't effect albedo by more than a cat's whisker. Reason? Open water steams furiously in summer. When this was discovered, the research team removed their prelim results from the net (I saw them!) and I doubt it was published as too inconvenient. But other's have reported this. Result: ZERO. Even I can write zero on the back of a piece of paper. (It might actually promote cooling, which is a negative feedback) I was more interested in poitsplace *justifcation* for his claim that ice albedo feedback is overestimated, or whether it was just related to a belief that climate scientists don't think of the obvious. While the following abstract suggests that albedo is falling roughly at the same proportion as sea ice, further scanning of the literature is suggestive of an ongoing debate about various effects of reduced ice melt and changing cloud amount, which belies poitsplace assumption of a lack of inquiry by the scientists. alaska.usgs.gov/geography/conference/abstracts/tschudi_abstract.pdf
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Post by icefisher on May 21, 2009 17:24:08 GMT
But other's have reported this. I was more interested in poitsplace *justifcation* for his claim that ice albedo feedback is overestimated, or whether it was just related to a belief that climate scientists don't think of the obvious. Simply by that statement its obvious you haven't descended the steps of your ivory tower for a long long time. Absolutely they don't think of the obvious. It happens every day. I
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Post by socold on May 21, 2009 18:28:44 GMT
A key skeptic argument on this thread has been that if positive feedbacks existed they would cause temperature to continue rising indefinitely. For example when you said: "It doesn't matter how SMALL the positive feedback is - if there are no negative feedbacks the rise in temperature is now totally unstoppable. It will also accelerate on a compounding basis." This aint how it works and isn't what Hansen is saying. Hansen agrees with me that positive feedback in climate causes an amplification of the forcing. So for every 4wm-2 forcing you get about 3C temperature rise. That's it. Max. You don't get more unless you increase the forcing some more. The idea that positive feedback leads to temperature rising until negative feedback cuts in is not using the correct definition of feedback. SoCold you are missing the issue - CO 2 is not the only cause of warming by absorption in the atmosphere - in fact the 'feedback' that AGW relies on is water vapor that it is claimed will increase and amplify the 'greenhouse' (sic) effect. That is where you want to stop your argument. However, the water vapor is not sentient and doesn't realize that the warming it has caused is due to its own effect - so it goes on to evaporate more as the atmosphere is warmer causing more positive feedback But crucially it's less than the amount it takes to cause it to rise. 1C warming causes additional 0.5C warming from water vapor The additional 0.5C warming from water vapor causes an additional 0.25C warming from water vapor. The additional 0.25C warming from water vapor causes an additional 0.125C warming from water vapor. You can see it's getting smaller. It won't go to infinity as you propose (despite telling me last post that I was the only one talking about infinity)
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Post by magellan on May 22, 2009 1:22:09 GMT
SoCold you are missing the issue - CO 2 is not the only cause of warming by absorption in the atmosphere - in fact the 'feedback' that AGW relies on is water vapor that it is claimed will increase and amplify the 'greenhouse' (sic) effect. That is where you want to stop your argument. However, the water vapor is not sentient and doesn't realize that the warming it has caused is due to its own effect - so it goes on to evaporate more as the atmosphere is warmer causing more positive feedback But crucially it's less than the amount it takes to cause it to rise. 1C warming causes additional 0.5C warming from water vapor The additional 0.5C warming from water vapor causes an additional 0.25C warming from water vapor. The additional 0.25C warming from water vapor causes an additional 0.125C warming from water vapor. You can see it's getting smaller. It won't go to infinity as you propose (despite telling me last post that I was the only one talking about infinity) Once again, there isn't a shred of evidence to support such nonsense.
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Post by nautonnier on May 22, 2009 2:11:13 GMT
SoCold you are missing the issue - CO 2 is not the only cause of warming by absorption in the atmosphere - in fact the 'feedback' that AGW relies on is water vapor that it is claimed will increase and amplify the 'greenhouse' (sic) effect. That is where you want to stop your argument. However, the water vapor is not sentient and doesn't realize that the warming it has caused is due to its own effect - so it goes on to evaporate more as the atmosphere is warmer causing more positive feedback But crucially it's less than the amount it takes to cause it to rise. 1C warming causes additional 0.5C warming from water vapor The additional 0.5C warming from water vapor causes an additional 0.25C warming from water vapor. The additional 0.25C warming from water vapor causes an additional 0.125C warming from water vapor. You can see it's getting smaller. It won't go to infinity as you propose (despite telling me last post that I was the only one talking about infinity) Seems like a good disproof of the AGW claim that water vapor will cause the majority of the rise in temperature after its positive feedback is triggered by CO 2However, to satisfy the curious - please give citations for your claims of the geometric reduction in forcing.
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Post by poitsplace on May 22, 2009 4:30:12 GMT
I was more interested in poitsplace *justifcation* for his claim that ice albedo feedback is overestimated, or whether it was just related to a belief that climate scientists don't think of the obvious. While the following abstract suggests that albedo is falling roughly at the same proportion as sea ice, further scanning of the literature is suggestive of an ongoing debate about various effects of reduced ice melt and changing cloud amount, which belies poitsplace assumption of a lack of inquiry by the scientists. alaska.usgs.gov/geography/conference/abstracts/tschudi_abstract.pdfYou're right, the albedo is still the albedo. The EFFECTIVE albedo is what's being misunderstood. Nobody cares how much energy coming in from space, the moon or alpha centauri is reflected. The only albedo we care about is relative to sunlight. The effective albedo of open water at the north pole is surpisingly similar to the albedo of ice at the angles at which it receives sunlight.. Then, during the winter when there's more ice at lower latitudes, the ice and snow in the arctic circle isn't even exposed to the sun. The ice is simply filling in the areas that aren't getting much sun. We should expect amplification from this to be quite low.
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Post by jurinko on May 22, 2009 7:50:12 GMT
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Post by steve on May 22, 2009 10:30:33 GMT
I was more interested in poitsplace *justifcation* for his claim that ice albedo feedback is overestimated, or whether it was just related to a belief that climate scientists don't think of the obvious. While the following abstract suggests that albedo is falling roughly at the same proportion as sea ice, further scanning of the literature is suggestive of an ongoing debate about various effects of reduced ice melt and changing cloud amount, which belies poitsplace assumption of a lack of inquiry by the scientists. alaska.usgs.gov/geography/conference/abstracts/tschudi_abstract.pdfYou're right, the albedo is still the albedo. The EFFECTIVE albedo is what's being misunderstood. Nobody cares how much energy coming in from space, the moon or alpha centauri is reflected. The only albedo we care about is relative to sunlight. The effective albedo of open water at the north pole is surpisingly similar to the albedo of ice at the angles at which it receives sunlight.. Then, during the winter when there's more ice at lower latitudes, the ice and snow in the arctic circle isn't even exposed to the sun. The ice is simply filling in the areas that aren't getting much sun. We should expect amplification from this to be quite low. Do the maths then.
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Post by steve on May 22, 2009 10:33:11 GMT
But crucially it's less than the amount it takes to cause it to rise. 1C warming causes additional 0.5C warming from water vapor The additional 0.5C warming from water vapor causes an additional 0.25C warming from water vapor. The additional 0.25C warming from water vapor causes an additional 0.125C warming from water vapor. You can see it's getting smaller. It won't go to infinity as you propose (despite telling me last post that I was the only one talking about infinity) Seems like a good disproof of the AGW claim that water vapor will cause the majority of the rise in temperature after its positive feedback is triggered by CO 2However, to satisfy the curious - please give citations for your claims of the geometric reduction in forcing. It's notable that many "debunks" of agw rely on debunking the simplified explanations such as "the greenhouse effect is not the same as a greenhouse" and "if the water vapour feedback is positive, how come we've not had a runaway effect".
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Post by poitsplace on May 22, 2009 11:08:57 GMT
It's notable that many "debunks" of agw rely on debunking the simplified explanations such as "the greenhouse effect is not the same as a greenhouse" and "if the water vapour feedback is positive, how come we've not had a runaway effect". There's little else to debunk. The modelers flat out admit they don't know how the actual systems work or what the actual affects are for each proposed feedback. We "deniers" as we're called are horribly limited by the fact that the AGW camp doesn't actually have any evidence. The only REAL evidence all points to low or negative feedbacks, little to no sensitivity to CO2 in general and the climate operating in radically different ways than the modelers suggest.
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