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Post by icefisher on Jun 9, 2009 16:30:45 GMT
Stop pretending like you do. Not all scientists agree on the subject, so where does that place you?There are bits that all agree on. The fundamental physics which results in a forcing change of ~3.7 w/m2 per doubling of CO2 is sound. LOL! you are the one confused GLC! 3.7watts per what? Square meter of the earth's surface? You are trying to separate water from wetness when you try to separate forcing from sensitivity. Can't be done in the real world. It is also incorrect to say the concept of 3.7watts/m2 is based on sound physics. There is nothing sound about it. Its probably even the preferred theory. More correctly its probably accurate to say its built on physics sound enough for most commercial applications of the physics. This is more a measure of need. Some theories are accepted simply because there is no real commercial interest in highly accurate representations of certain processes. Rough approximations satisfy the commercial needs. . . .most likely because nobody is building and selling worlds yet. . . .except for a few snake oil salesmen.
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Post by icefisher on Jun 9, 2009 17:28:31 GMT
Yes I understand that is the only experiment you know of is somebody gazing at a spectra analysis having a eureka moment that CO2 has an effect on our atmosphere, at least the top layer anyway, and bought in wholesale hook, line, and sinker into somebody's GCM.What do you mean by the following 1. "bought in wholesale hook, line, and sinker into somebody's GCM" 2. "at least the top layer anyway" Your response suggests to me that you don't actually understand what information is provided by an emission spectrum graph. Well since you have not yet given me the spectrum analysis that caused you to arrive at your conclusion, you are right! I don't understand it.
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Post by dmapel on Jun 9, 2009 19:11:22 GMT
glc,
I have been reading the barrett website that you pointed to as a good reference. You are correct. It is very good. I find his position on AGW to be very well thought out with a good scientific foundation (as much as I am capable of judging his scientific knowledge). I think the following pretty well summarizes his opinion:
Barrett: "The IPCC claim that most of the warming that occurred in the 20th century was caused by the increase in the atmospheric concentration of CO2 and that the observed increase in temperature of the Earth’s surface of 0.7 ± 0.2̊C was understandable. Our criticism is that the calculations of the effect of the CO2 change depended upon a greater sensitivity of the atmosphere to such changes. The IPCC regard the effect of doubling the atmospheric concentration of CO2 from the pre-industrial value of 285 ppmv to be roughly four times larger than estimates made from real events such as the Mount Pinatubo volcanic eruption of 1991. They claim that the enhancement of the greenhouse effect due to fossil fuel burning is discernible because of their possible error in using a sensitivity value which is too large. If, on the other hand, the sensitivity is considerably lower than that used by the IPCC the effect would not be discernible amongst the ‘noisy’ temperature records that have been recorded.
Much discussion is given to the very recent observations of temperature, the ones since 1997 as shown in the diagram kept up-to-date on the Breaking News page.
The peak anomaly in February 1998 [0.752̊C] was thought to be due mainly to the severe El Niño Southern Oscillation of that year. Soon after, the temperature anomaly in June 1999 was -0.137̊C and in May 2008 it was -0.18̊C. Interestingly, the value for the anomaly in April 1979, in the first full year of satellite observations the anomaly was -0.166̊C. As they say in Lancashire: ‘providing there’s no change, things will stay just the same’! Considering that the global temperature anomaly has changed from a peak of +0.75̊C in 1998 to -0.18̊C in May 2008 makes the global temperature change as measured by the irregularly placed thermometers around the world of 0.7 ± 0.2̊C over the 20th century seem of little importance or significance.
Statistics of the monthly satellite temperature anomalies over 39 years show that their standard deviation is 0.21̊C. Regression analysis shows that the trend is ~0.13̊C per decade. The trend lacks significance. There is no sign of any continual upward warming from the fossil fuel burning, but if this is small it would not matter if the global temperature was showing an upward or downward trend or even showing no trend at all. It would not be evident in the ‘noise’ of the measurements. This does not discourage some critics who are now claiming that the global temperature is decreasing and therefore there cannot be any effect from fossil fuel burning. They are wrong. It does seem as though the potential warming is small, but according to physics, it can’t be zero. If the IPCC sensitivity value is anywhere near the correct value, then a factor is operating to more than cancel out the predicted warming that we really know nothing about. It might be that the fossil fuel burning signal will never be discerned."
This is the latest from his Breaking News page: " The global temperature has not exceeded the 1998 value since that year and the trend [from satellite and terrestrial data] is one of cooling." (includes temp anomalies through April, 2009)
This guy doesn't seem to be one of those crackpot Christians, who would immediately be dismissed by the soclod's. I guess he could be a tool of BIG OIL or BIG TOBACCO, but not having seen any evidence of that I will give him the benefit of the doubt. He seems to be unworried about the extent of possible AGW. His is a voice that should be heard, but the debate is closed. What a shame.
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Post by glc on Jun 9, 2009 23:25:51 GMT
glc,
I have been reading the barrett website that you pointed to as a good reference. You are correct. It is very good. I find his position on AGW to be very well thought out with a good scientific foundation (as much as I am capable of judging his scientific knowledge). I think the following pretty well summarizes his opinion:
On the anti-AGW side there are 2 groups. Jack Barrett falls into the group who understand that extra CO2 in the atmosphere is likley to result in warming, but argue that the warming will not be a problem. The second group simply deny anything that is pro-AGW. It's possible to find examples of this on this blog.
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Post by glc on Jun 9, 2009 23:28:48 GMT
3.7watts per what? Square meter of the earth's surface?
You are trying to separate water from wetness when you try to separate forcing from sensitivity. Can't be done in the real world.
It is also incorrect to say the concept of 3.7watts/m2 is based on sound physics. There is nothing sound about it. Its probably even the preferred theory.
More correctly its probably accurate to say its built on physics sound enough for most commercial applications of the physics. This is more a measure of need. Some theories are accepted simply because there is no real commercial interest in highly accurate representations of certain processes.
Rough approximations satisfy the commercial needs. . . .most likely because nobody is building and selling worlds yet. . . .except for a few snake oil salesmen.
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Post by glc on Jun 9, 2009 23:56:23 GMT
I can't believe I'm bothering to respond to this but - what the heck
3.7watts per what? Square meter of the earth's surface?
Err - yes. You should have made it clear some time back that you weren't familiar with the terminology. It would have saved me a lot of time and effort.
You are trying to separate water from wetness when you try to separate forcing from sensitivity. Can't be done in the real world.
Why can't it? Forcing is related to the extra amount of energy which is blocked by the increase in CO2. Climate Sensitivity is a measure of the temperature response to that forcing. So we might have 2 scientists (A & B) who both agree that the change in forcing due to doublimg the CO2 concentration is 4 w/m2. Scientist A, though, thinks there will be strong positive feedback to the forcing that will result in a climate sensitivity of 0.75 deg per w/m2 which will produce an increase in temperature of 3 deg (i.e. 4 x 0.75). Scientist B, on the other hand, thinks they'll be no feedback and he believes that climate sensitivity will only be 0.25 deg per w/m2 which means the warming will only be 1 deg (i.w. 4 x 0.25). This is what the main argument is about. There is broad agreement on the forcing, but considerable disagreement on the sensitivity.
It is also incorrect to say the concept of 3.7watts/m2 is based on sound physics. There is nothing sound about it. Its probably even the preferred theory.
I suppose this must mean something but I'm not prepared to analyse it too deeply. Suffice to say that the 3.7 w/m2 number is a calculation of the forcing due to a doubling of CO2 in the atmosphere. The method of calculation is built on 'sound' physics.
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Post by glc on Jun 10, 2009 0:01:58 GMT
Well since you have not yet given me the spectrum analysis that caused you to arrive at your conclusion, you are right! I don't understand it. Ok here's an example www.barrettbellamyclimate.com/page16.htmExplain what this means. Start by telling me what the "IR window" region is.
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Post by icefisher on Jun 10, 2009 1:12:07 GMT
Why can't it? Forcing is related to the extra amount of energy which is blocked by the increase in CO2. Climate Sensitivity is a measure of the temperature response to that forcing. Its easy to see why you are confused. According the definition given its not 3.7 watts/m2 at the surface of the earth but instead the net IR interacted with by CO2 at the tropopause. If you take the area in question and multiply it times 3.7 watts you get the total amount of energy. The total amount of energy in question isn't an issue. But when you start calling it a "forcing" or that is the amount of energy "blocked" you are beginning to imply characteristics that properly belong in the sensitivity discussion. Apparently even you have been deceived by the language as evidenced by your belief its an effect felt at the surface of the earth. Whether its felt at the surface of the earth is dependent upon all sorts of issues, from how the energy is disposed of to feedbacks. Scientists aren't quibbling over the words what they are quibbling over are the effects on the world by a certain amount of energy that needs to get through a cloud of CO2. There would be no problem with this confusion if you actually had the studies you have been asked for.
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Post by poitsplace on Jun 10, 2009 4:21:01 GMT
There are actually two issues here dealing with the limit of the radiation CO2 can stop. The first is that CO2 will always emit its own radiation due to thermal excitation. So since the coldest part of the atmosphere is 220k, the radiation it blocks won't ever drop below the levels of 220k black body radiation.
But then you need to ask yourself...what happens to the extra energy? See, the assumption is that a significant portion goes all the way to the ground. There's a problem with this though. First off, MOST of the atmosphere is below the bottleneck. It's almost certainly going to have to bang around quite a few times before it could possibly get to the ground.
But most of CO2's radiation has to run the water vapor gauntlet. Water vapor dominates the troposphere and is at such incredibly high quantities that it is sure to catch a disproportionate amount of CO2's radiation. At the same time, water vapor has a much larger spectrum.
Going down through the atmosphere MOST of CO2's "back radiation" is far more likely to hit water vapor than CO2. Water vapor has a greater capacity to emit that energy. Water vapor will tend to (more often than not) emit outside of CO2's much smaller spectrum). Water vapor has a far greater capacity to store the energy temporarily in a way that won't show up as heat OR radiation.
Do you see what happens when you use half of the physics or concentrate on one thing? The water vapor in the troposphere is an incredible, energy eliminating machine. However much energy is slowed by CO2...most will be eliminated by water vapor. Its an interplay between the two since they share the same emission frequencies...but water vapor holds the upper hand in ALL respects. Its frequencies are the most efficiently emitted at those temperatures. It emits in more bands. It's at far higher concentrations. It can store heat temporarily without increasing temperature.
Saying CO2 will cause X warming because of its X more absorption (even it's absorption adjusted to the minimum temperature) is like saying all cars should get the same mileage because the gas has the same energy content.
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Post by dmapel on Jun 10, 2009 4:25:45 GMT
glc: "On the anti-AGW side there are 2 groups. Jack Barrett falls into the group who understand that extra CO2 in the atmosphere is likley to result in warming, but argue that the warming will not be a problem. The second group simply deny anything that is pro-AGW. It's possible to find examples of this on this blog." Well, I am in the group that approaches complex scientific issues on a need to know basis. For example, I am not too concerned about whether the Universe began with a Big Bang!, or a little whimper. I know I am here, and I don't worry too much about the esoteric, and possibly unknowable details on how I got here. I only became concerned enough to pay close attention to this issue, when I learned the fancy school we send my 5 year old son to has been indoctrinating him with that hysterical catastrophic AGW BS. If someone says, "CO2 will definitely cause some warming", I say OK, "How much?" I sift through the various answers and other information on that, and if I decide the answer is "Not enough to worry about", then I am not going to fight about radiative forcing formulas. I don't really care if CO2 forcing can theoretically cause some warming, because I haven't seen even half-way convincing evidence that it has caused any significant warming, up to now. I am still waiting for some heat. I posted this because I thought it might interest those looking for a way to calculate CO2 radiative forcing that would give them a result different than the IPCC result. They don't seem to be interested. I am curious to know what you think about it, if you care to have a look: www.john-daly.com/forcing/moderr.htm“Radiative forcing The additional IR absorption (being evaluated here for CO2 doubling) is the energy source for global warming. HITRAN transmission spectra – the fringes being by no means saturated yet – can be used to compute this absorption, mostly occurring near ground. A simple radiative energy equilibrium model of the troposphere yields an IPCC-conforming radiative forcing which is here defined as the additional energy re-radiated to ground. Coping with water vapor overlap on the low frequency side of the 15 ?m band, the clear sky CO2 forcing is considerably reduced to 1.9 W/m². With vapor feedback and for cloudy sky the equilibrium ground warming will be about 0.4 to 0.6 ?C only – a factor 4 to 6 less than IPCC's 'best guess' for CO2 doubling.” And here, several alleged calculations of expected warming assuming that the IPCC forcing estimate is correct: www.junkscience.com/Greenhouse/What_Watt.html“What does this 3.7 Wm-2 mean?” Oh, and this is very interesting, from barrettbellamy, on calculating climate sensitivity based on the climate's reaction to the Mt. Pinatubo eruption: www.barrettbellamyclimate.com/page25.htm
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Post by glc on Jun 10, 2009 9:19:45 GMT
Its easy to see why you are confused. According the definition given its not 3.7 watts/m2 at the surface of the earth but instead the net IR interacted with by CO2 at the tropopause.
I am not confused. You clearly are. I asked you to explain what the IR window is. Start with that. Tell me what it means. Tell me what is implied by the different temperature bands.
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Post by glc on Jun 10, 2009 10:23:55 GMT
I posted this because I thought it might interest those looking for a way to calculate CO2 radiative forcing that would give them a result different than the IPCC result. They don't seem to be interested. I am curious to know what you think about it, if you care to have a look:Ok but I'll need a bit of time but here a re a few brief comments. www.john-daly.com/forcing/moderr.htmThis is Peter Dietze's article which I did read some time. I'll have to come back on that. And here, several alleged calculations of expected warming assuming that the IPCC forcing estimate is correct:I think these both give a figure that is too low (i.e. ~0.2 deg per w/m2). However, it should be noted that even this low figure gives a total warming of ~0.7 deg which is not a million miles from my ~1 deg estimate. www.junkscience.com/Greenhouse/What_Watt.html “What does this 3.7 Wm-2 mean?”Steve Milloy uses an invalid calculation. Basically he uses the the change in temperature due to the greenhouse effect (~33 deg) and divides it by the total ghg forcing (155 w/m2). On the face of it this seems quite reasonable, but things are not quite as simple as that. The key relationship is the change at the Top of the Atmosphere. I'll try and cobble together some simple numbers to demonstrate. Oh, and this is very interesting, from barrettbellamy, on calculating climate sensitivity based on the climate's reaction to the Mt. Pinatubo eruption:
www.barrettbellamyclimate.com/page25.htmI doubt if JB is putting this forward as a robust figure - more as an indicator that IPCC sensitivity is too high. The problem with using Pinatubo is the issue of equilibrium. Following the Pinatubo eruption millions of tons of aerosols were blasted into the stratosphere where it spread and covered the earth in a thin veil which reflected the sun's energy away from the earth causing temperatures to fall. After a few months the 'dust' began to clear and within 2-3 years it had completely gone. What would have happened, though, if the aerosols had remained in the stratosphere for 5 or 10 years or more. Let's say the peak negative forcing (-2.7 w/m2), rather than lasting a few months, had gone on for several years. Is it not likely that temperatures would have fallen still further. As an analogy consider this: Imagine it is -10 degrees outside. Now place a bucket of water in your garden. Five minutes later you go out to check. The water is still liquid. It is not yet frozen. Does this mean it's not really -10 degrees or water freezes at a much lower temperature. No it just means that the water and air are not "in equlibrium". The water is still losing heat.
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Post by magellan on Jun 10, 2009 14:11:16 GMT
I posted this because I thought it might interest those looking for a way to calculate CO2 radiative forcing that would give them a result different than the IPCC result. They don't seem to be interested. I am curious to know what you think about it, if you care to have a look:Ok but I'll need a bit of time but here a re a few brief comments. www.john-daly.com/forcing/moderr.htmThis is Peter Dietze's article which I did read some time. I'll have to come back on that. And here, several alleged calculations of expected warming assuming that the IPCC forcing estimate is correct:I think these both give a figure that is too low (i.e. ~0.2 deg per w/m2). However, it should be noted that even this low figure gives a total warming of ~0.7 deg which is not a million miles from my ~1 deg estimate. www.junkscience.com/Greenhouse/What_Watt.html “What does this 3.7 Wm-2 mean?”Steve Milloy uses an invalid calculation. Basically he uses the the change in temperature due to the greenhouse effect (~33 deg) and divides it by the total ghg forcing (155 w/m2). On the face of it this seems quite reasonable, but things are not quite as simple as that. The key relationship is the change at the Top of the Atmosphere. I'll try and cobble together some simple numbers to demonstrate. Oh, and this is very interesting, from barrettbellamy, on calculating climate sensitivity based on the climate's reaction to the Mt. Pinatubo eruption:
www.barrettbellamyclimate.com/page25.htmI doubt if JB is putting this forward as a robust figure - more as an indicator that IPCC sensitivity is too high. The problem with using Pinatubo is the issue of equilibrium. Following the Pinatubo eruption millions of tons of aerosols were blasted into the stratosphere where it spread and covered the earth in a thin veil which reflected the sun's energy away from the earth causing temperatures to fall. After a few months the 'dust' began to clear and within 2-3 years it had completely gone. What would have happened, though, if the aerosols had remained in the stratosphere for 5 or 10 years or more. Let's say the peak negative forcing (-2.7 w/m2), rather than lasting a few months, had gone on for several years. Is it not likely that temperatures would have fallen still further. As an analogy consider this: Imagine it is -10 degrees outside. Now place a bucket of water in your garden. Five minutes later you go out to check. The water is still liquid. It is not yet frozen. Does this mean it's not really -10 degrees or water freezes at a much lower temperature. No it just means that the water and air are not "in equlibrium". The water is still losing heat. Do I sense a bit more hubris in your musings as time goes on? On the subject of climate sensitivity, you have inferred to have it all figured out. Please, in your own words, analyze Lindzen's recent presentation based on observations vs models. I don't have the audio portion, but have posted the PPT where he states wattsupwiththat.files.wordpress.com/2009/06/richard-lindzen-3.pptWhat we see, then, is that the very foundation of the issue of global warming is wrong. You and steve concentrate heavily on theoretical aspects of specific components, but do not provide evidence of the net effect on the system as a whole. That is the crux of the matter, and one reason why warmers get gobsmackd in debates and can't provide real world evidence to support their argument. Compare John Christy to William Schlessinger in this debate as a prime example: penoflight.com/climatebuzz/?page_id=417That the first few meters of ocean contains more heat than the entire atmosphere seems to evade the discussion. I've yet to see a numerical explanation for how anything but short wave solar radiation can account for warming of the oceans. Do you have it by chance?
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Post by icefisher on Jun 10, 2009 15:51:32 GMT
Its easy to see why you are confused. According the definition given its not 3.7 watts/m2 at the surface of the earth but instead the net IR interacted with by CO2 at the tropopause.I am not confused. You clearly are. I asked you to explain what the IR window is. Start with that. Tell me what it means. Tell me what is implied by the different temperature bands. So you are saying the IPCC has the wrong definition of a forcing? Whose definition are you using? I will say you are correct that the 3.7watts/m2 is the least controversial part of the AGW theory. Thats because everybody agrees on the sign. Everybody agrees that more CO2 is a positive forcing on atmospheric temperature.
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Post by magellan on Jun 10, 2009 16:31:45 GMT
Its easy to see why you are confused. According the definition given its not 3.7 watts/m2 at the surface of the earth but instead the net IR interacted with by CO2 at the tropopause.I am not confused. You clearly are. I asked you to explain what the IR window is. Start with that. Tell me what it means. Tell me what is implied by the different temperature bands. So you are saying the IPCC has the wrong definition of a forcing? Whose definition are you using? I will say you are correct that the 3.7watts/m2 is the least controversial part of the AGW theory. Thats because everybody agrees on the sign. Everybody agrees that more CO2 is a positive forcing on atmospheric temperature. Please folks, humor me just for a moment. If AGW warms the oceans, how and how much? I only understand numbers. www.cdc.noaa.gov/people/gilbert.p.compo/CompoSardeshmukh2007a.pdf
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