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Post by socold on Jun 18, 2009 19:27:53 GMT
About 1C warming per co2 doubling So...since it is unreasonable to assume greater than a 1 to 1 feedback, you agree that the top end on the IPCC estimates MUST be wrong and that the actual figures lie somewhere under a maximum of a 2C increase...and more likely under the error bars of the models (which would be feedback of about .7 to 1). Right? Why is unreasonable to consider a greate than 1 to 1 feedback?
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Post by trbixler on Jun 19, 2009 2:14:13 GMT
Socold Even without a sign maybe you have invented either perpetual motion or maybe an infinite sink, cool or maybe hot can't tell yet. ;D
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Post by poitsplace on Jun 19, 2009 4:23:14 GMT
So...since it is unreasonable to assume greater than a 1 to 1 feedback, you agree that the top end on the IPCC estimates MUST be wrong and that the actual figures lie somewhere under a maximum of a 2C increase...and more likely under the error bars of the models (which would be feedback of about .7 to 1). Right? Why is unreasonable to consider a greate than 1 to 1 feedback? The fact that you would even consider a greater than 1 to 1 feedback shows a lack of any sort of functionality to your "understanding" of the concepts. The feedbacks cannot discriminate between their own output and that of what you (laughably) are considering the primary driver of climate. For an example let's look at... Volcanic eruption: A volcano goes off and reduces the temperature of the earth for several years. We'll say the initial forcing is capable of a .3C drop. Now the feedbacks kick in and the temperature drops an additional .4C. However, even after a complete recovery from the volcanic eruption (in terms of ash) the feedbacks are STILL in effect because they've over driven the original forcing by .1C (if not more driven by the .7C overall drop). BUT even that .1C is sufficient to drive the feedbacks and they'll STILL continue just fine on their own inertia. the .1C soon after would lead to .2C, the .2C would soon lead to .4C, the .4C to .9C (I'm rounding to make it quicker). Now this was a gross oversimplification. In reality the earth likely wouldn't have EVER recovered from the volcanic eruption for a start. And of course as you do seem to be aware the feedbacks would eventually hit a physical limit...like the earth being completely covered in ice or completely free of ice). Now SOME of the IPCC's high end estimates actually require feedbacks of greater than 2 to 1. These should never have been considered. ONLY a computer modeler would ever consider this because anyone with any practical experience would know that in systems with such incredibly high feedbacks the system would immediately force the entire system to the limits of the feedback. Interestingly enough we are actually quite close to the limits of the feedbacks here on earth. The HIGHEST temperature across the antarctic plateau is something like -28. That ice isn't going anywhere and there's nothing we can do about it. Even if it DID go somewhere it still wouldn't do as much warming as everyone thinks. Ice at the poles has extremely limited feedback potential because there's just not much sunlight hitting it. In fact, for half of the year there's NO SUNLIGHT hitting it. Ice albedo..the MAIN feedback..does indeed have potential for greater amplification but only as world temperatures FALL. Anyway, my point is that feedbacks greater than 1 to 1 would have already showed up. You'd expect to see WILD temperature fluctuations..far greater than the piddly amounts of noise we see now. The reasonably stable temperatures are themselves evidence that while strong feedbacks may exist...they're sure as heck not pushing anything significantly higher than current temperatures or lower than the ice-age temperatures.
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Post by socold on Jun 19, 2009 9:21:44 GMT
Why is unreasonable to consider a greate than 1 to 1 feedback? Now SOME of the IPCC's high end estimates actually require feedbacks of greater than 2 to 1. These should never have been considered. ONLY a computer modeler would ever consider this because anyone with any practical experience would know that in systems with such incredibly high feedbacks the system would immediately force the entire system to the limits of the feedback. The only reason you see a problem is because you are using a different definition of "1 to 1 feedback" than me. You are using it to mean for each 1C rise in temperature a 4wm-2 forcing will occur (this is far higher than what the IPCC reports), which will in turn cause 1C warming, which again due to "1 to 1" will cause 4wm-2 more forcing, etc to infinity. On the otherhand I take it that 1 to 1 feedback means in any temperature change half of the change is due to feedback (the other half the forcing). So what would have been 0.4C warming in a no feedback world would become 0.8C warming in a "1 to 1" feedback world. A no feedback world would have a feedback ratio of "0 to 1 " (ie all warming is from the forcing, none from feedback. "2 to 1" feedback would mean temperature response is trebled from what it would be in a none feedback world, the feedback accounting for 2/3 of the temperature response. "-0.5 to 1" feedback would mean temperature response was halved from what it would be in a none feedback world. So what would have been a 0.6C rise in a non feedback world would become a 0.3C rise in this negative feedback world. Negative feedback acts to stablize climate. Runaway warming would be "infinity to 1" feedback. Ie just about all of the warming would be due to the feedback. Under this definition the IPCC are not reporting feedbacks that lead to runaway. This makes sense because if proposed feedbacks lead to runaway noone would accept them. You should be suspicious that your argument makes no sense in this case as it is beyond reasonable to think that climate sensitivities of 2C per doubling of co2 have such a simple flaw. The IPCC report that feedbacks are strong enough so that what would have been a maximum temperature rise of 1C actually becomes a maximum temperature rise of about 3C. Ie that 3C is the total end effect of the feedback, or in other words every temperature change is two parts due to the feedback. To make all this clearer, it's easier to look at the proposed feedback in terms of actual physical units rather than just using "1 to 2" or "2:1" notation. This is close to what the IPCC are reporting on: 1) Each 4wm-2 forcing causes 1C temperature rise 2) Each 1C temperature rise causes a 2.66wm-2 forcing (this is the feedback), ie the feedback is 2.66wm-2/C (wm-2/C is a very good unit for feedback) This can be written out as an equation: TempRise = Forcing*0.25 + TempRise*Feedback*0.25Which in terms of TempRise gives: TempRise = (forcing * 0.25) / (1 - feedback*0.25)The climate sensitivity from models that gives a rough 3C warming per doubling of co2 are based on this: So, for 3C warming per doubling of co2, each 1C temperature rise must cause a 2.66wm-2 forcing: 3C = (4wm-2 * 0.25) / (1 - 2.66wm-2/C * 0.25)
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Post by trbixler on Jun 19, 2009 14:00:21 GMT
socold Now we have some signs and we just throw in a .25 factor. Maybe to make sure that it is not either under damped or over damped. But .25 is around 1 quater a nice AGW amount. Why?
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Post by socold on Jun 19, 2009 16:20:18 GMT
Sorry i didn't explain that. The 0.25 is for the amount of warming caused by 1wm-2 forcing - excluding feedbacks. I guess more accurately it should be 1C / 3.7wm-2
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Post by icefisher on Jun 19, 2009 17:32:26 GMT
The only reason you see a problem is because you are using a different definition of "1 to 1 feedback" than me. You are using it to mean for each 1C rise in temperature a 4wm-2 forcing will occur (this is far higher than what the IPCC reports), which will in turn cause 1C warming, which again due to "1 to 1" will cause 4wm-2 more forcing, etc to infinity. Trying to get a handle on this. So you are calling BS on Al Gore's tipping point right?
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Post by socold on Jun 19, 2009 21:52:51 GMT
Tipping point doesn't mean temperature rise to infinity, it means a point of no return (or little chance of return). Like for example if amazon rainforest dieback did occur it would be a tipping point because once gone the water cycle in the region would change so much it would prevent the rainforest from reestablishing.
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Post by trbixler on Jun 20, 2009 1:34:07 GMT
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Post by socold on Jun 20, 2009 1:57:36 GMT
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Post by poitsplace on Jun 20, 2009 3:56:39 GMT
Now SOME of the IPCC's high end estimates actually require feedbacks of greater than 2 to 1. These should never have been considered. ONLY a computer modeler would ever consider this because anyone with any practical experience would know that in systems with such incredibly high feedbacks the system would immediately force the entire system to the limits of the feedback. The only reason you see a problem is because you are using a different definition of "1 to 1 feedback" than me. You are using it to mean for each 1C rise in temperature a 4wm-2 forcing will occur (this is far higher than what the IPCC reports), which will in turn cause 1C warming, which again due to "1 to 1" will cause 4wm-2 more forcing, etc to infinity. Oh, sorry, if you'r egoing to define it so that 1 to 1 means double the initial forcing then you can't even have that. Please, mister wizard...explain to me the process by which the feedbacks discern their own warming from the "primary forcing" so they only amplify the primary forcing. Last time I checked water wasn't able to tell the difference between sources of (for example) a 2C increase in temperature so that it would melt/warm/evaporate faster with one than the other.
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Post by socold on Jun 20, 2009 5:05:26 GMT
Take this example:
1) 1C per 4wm-2 (this is the direct temperature response to forcing) 2) 2.66wm-2 per 1C (this is the feedback)
These two lead to total warming of 3C for a 4wm-2 forcing.
In other words instead of 1C warming without feedbacks, we have 3C warming with feedbacks. But this is not the feedback itself. This is not saying that each 1C warming will cause an additional 2C warming. It stops at 3C. No more.
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Post by trbixler on Jun 20, 2009 5:18:07 GMT
socold As usual no direct answer as to why there is no warming in the last 10 years, only picking different end points. You hide in obfuscation. Verbosity and willingness to prattle is no answer as to why the temperatures have not gone up, other than you have no idea or do not care to know.
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Post by socold on Jun 20, 2009 5:39:30 GMT
socold As usual no direct answer as to why there is no warming in the last 10 years, only picking different end points. You hide in obfuscation. Verbosity and willingness to prattle is no answer as to why the temperatures have not gone up, other than you have no idea or do not care to know. Warming in the past 10 years has probably been masked first by the recent descent into solar minimum and secondly by declining ENSO. The 10 years does start with a super el nino and ends with a la nina afterall. This is why I picked a different period to show that the rising trend can be masked over a decade. In that case again this coincided with a solar minimum and pinatubo. I have heard there is a detected 0.1C cycle in global temperature caused by the ~11 year solar cycle. If so then obviously a 10 year period that ends in the solar minimum will suffer a -0.1C/decade "bias" which will cancel out much of any warming trend.
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Post by trbixler on Jun 20, 2009 14:47:58 GMT
socold 1998 was near the peak of a solar maximum. As the sun reached its peak so did the temperatures (with some delay). We are currently in a minimum or possibly a grand minimum and the temperatures are falling. The value of the solar "forcing" is not known, so to attribute some value to the sun is just a guess and does not take all solar effects into account. In previous minimums the temperatures have declined beyond whatever guess has been made. In history the temperatures have gone above the 1998 temperatures, leading a rational person to believe that the sun is the driver of climate. Currently every metric shows declining temperatures as CO2 is increasing falsifying CO2 as the driving force greenhouse gas. If one were to pick a greenhouse gas that matches the characteristics of our current knowledge of climate it would be water vapor. Unfortunately there is no profit for government or corporations or action groups in picking water vapor.
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