|
Post by duwayne on Jun 8, 2009 11:12:24 GMT
So according to this, two-thirds of the possible CO2 absorption is already being captured by other GHGs, AND THE AUTHOR QUESTIONS WHETHER THE MODELS ADEQUATELY ACCOUNT FOR THE OVERLAP.Gosh - I hadn't spotted that. This completely demolishes my argument. Thank you, jtom, I am well aware there is an overlap in the CO2 and WV absorption bands. Even the IPCC and RC are aware of it. It doesn't alter the fact, though, that increasing CO2 will, as shown by well understood radiative transfer equations, impede the flow of outgoing LW radiation from the earth's atmosphere. Rest assured I choose my sources carefully. Jack Barrett is a leading climate sceptic (though on this blog he'd be considered a rampant warmista) who has argued for many years (since 1992 at least) with prominent figures in the IPCC. JB says pretty much what I'm saying here, i.e. doubling the concentration of CO2 in the atmosphere will raise global temperatures by about a degree. Icefisher (like a few others) does not accept the well established science put forward by Barrett (and Lindzen and Spencer and Christy ....) and instead appears to have developed his own theory on how various gas molecules interact with IR radiation. GLC, When you say "Jack Barrett is a leading climate sceptic", what is your definition of "climate sceptic" ?
|
|
|
Post by steve on Jun 8, 2009 11:17:37 GMT
You need to read this which compares a range of radiation models.
New estimates of radiative forcing due to well mixed greenhouse gases G Myhre, EJ Highwood, KP Shine, F Stordal - Geophysical research letters - 1998
You need to follow the references for the radiation models to find what underlies them (presumably MODTRAN/HITRAN or similar).
One example of observational evidence for the change in outgoing emissions with a change in CO2 levels is:
Volume 16, Issue 22 (November 2003) Journal of Climate Observations of the Infrared Outgoing Spectrum of the Earth from Space: The Effects of Temporal and Spatial Sampling H. E. Brindley and J. E. Harries
I couldn't find a reference for the law of conservation of energy. This says that if energy is not getting out of a system, it must increase the internal energy of that system. There is more basic science to explain the relationship between energy content and temperature of a gas and/or liquid - basic undergrad stuff.
Just to preempt, Jim doesn't think any of this counts, but I don't understand his reasons. Since he thinks I'm a warmaholic when, actually, I prefer cooler temperatures...
|
|
|
Post by glc on Jun 8, 2009 11:28:57 GMT
The warmaholics claim that there is science to support their case. I have seen very little science in this discussion. But, again, many thanks for confirming my funny internal feelings
What do you mean by evidence? What is it you are looking for? I've given you the radiative transfer equations. I can't work out the numbers for you because it requires thousands of calculations. But the calculations can be done using programs such as MODTRAN. The results of MODTRAN can be, and are, validated. For example, we can compare the output from MODTRAN with satellite observations of emission spectra. Laboratory experiments also support MODTRAN results.
Now please tell me how much more evidence you need. You ask for papers to show that a doubling of CO2 results in a change of forcing of ~3.7 w/m2. Why would there be such a paper? It would simply involve running a program with appropriate input. A task that could be performed by any number of researchers. Try and put down in simple detail what it is you require as evidence.
|
|
|
Post by glc on Jun 8, 2009 11:37:13 GMT
GLC,
When you say "Jack Barrett is a leading climate sceptic", what is your definition of "climate sceptic" ?
Someone who understands the science but is sceptical that the effect of increasing ghgs is of the magnitude claimed by the AGW consenus. Jack Barrett has spent much of the last 15 years arguing against what he considers exaggerated warming claims.
Please don't confuse proper scepticism with the denial of well established science.
|
|
|
Post by icefisher on Jun 8, 2009 13:54:29 GMT
I don't care what his credentials are GLC thats not scientific evidence. I would have thought that the thousands upon thousands of laboratory experiments that take place daily and consistently show that the IR absorption properties of various gases are exactly as Barrett describes would be enough. I'm now deeply suspicious of what you're asking as I suspect that, whatever my response, it's not going to be enough to satisfy you. Ok - what the heck - I'll play along What is it that you are not convinced about? You haven't shown me a single experiment that demostrates the atmosphere operates as you have described. I understand that people have done a lot of work on IR radiation but I have not seen anything that verifies that the experiments in question are adequately accurate to detect IR emissions to the level of accuracy necessary to account for the fact CO2 only makes up .04% of the atmosphere. Errors here of very small magnitude potentially can completely negate how the system works. You seem perfectly satisfied with a far less rigorous standard of experimentation, can you explain why? And how do you deal with the corrolary to all this that a bag of warm non-ghg gases out in space in a bag transparent to IR would never cool.
|
|
|
Post by icefisher on Jun 8, 2009 14:08:53 GMT
The warmaholics claim that there is science to support their case. I have seen very little science in this discussion. But, again, many thanks for confirming my funny internal feelingsWhat do you mean by evidence? What is it you are looking for? I've given you the radiative transfer equations. I can't work out the numbers for you because it requires thousands of calculations. But the calculations can be done using programs such as MODTRAN. The results of MODTRAN can be, and are, validated. For example, we can compare the output from MODTRAN with satellite observations of emission spectra. Laboratory experiments also support MODTRAN results. Now please tell me how much more evidence you need. You ask for papers to show that a doubling of CO2 results in a change of forcing of ~3.7 w/m2. Why would there be such a paper? It would simply involve running a program with appropriate input. A task that could be performed by any number of researchers. Try and put down in simple detail what it is you require as evidence. Voodoo GLC. You may as well be sticking pins in dolls as much as you know about the validation of the GCMs.
|
|
|
Post by icefisher on Jun 8, 2009 14:17:55 GMT
The results of MODTRAN can be, and are, validated. For example, we can compare the output from MODTRAN with satellite observations of emission spectra. Laboratory experiments also support MODTRAN results. Which laboratory experiments GLC? Explain how accuracy of the intensity of back radiation was calculated.
|
|
|
Post by glc on Jun 8, 2009 14:36:12 GMT
Voodoo GLC. You may as well be sticking pins in dolls as much as you know about the validation of the GCMs.
I didn't mention GCMs.
Which laboratory experiments GLC? Explain how accuracy of the intensity of back radiation was calculated
Back radiation isn't part of the current disussion. At the moment, it's purely about calculating the transmission of IR through the atmosphere. I say that this can be done with a fair degree of accuracy. What's more a lot of prominent scientists (both sceptic and pro-AGW) agree with me.
|
|
|
Post by icefisher on Jun 8, 2009 14:48:46 GMT
Back radiation isn't part of the current disussion. At the moment, it's purely about calculating the transmission of IR through the atmosphere. I say that this can be done with a fair degree of accuracy. What's more a lot of prominent scientists (both sceptic and pro-AGW) agree with me. Well back radiation is key to the climate theory espoused by the warmistas but we will put that on the back burner for a moment along with several other heat transfer mechanisms in the atmosphere and focus on just this one issue. What is a fair degree of accuracy? As I pointed out if you are not at a level of 99.9% accuracy you could be off by an amount to reduce the expected warming by 60% from 1 degree per doubling to .4 degrees doubling. There is no margin for error at the levels of CO2 in the atmosphere. You need to make a case for permanent warmth of the bag of non-GHG in outer space to make your model fly. Its my view that in the absence of extremely accurate measurements of IR from gases, one should not assume that oxygen and nitrogen do not emit IR at low levels. . . .and if they do even at a rate of one thousandth that of CO2 you have a whole new ballgame.
|
|
|
Post by jimcripwell on Jun 8, 2009 15:09:41 GMT
glc writes "Try and put down in simple detail what it is you require as evidence.":
I have put this request before, as you can see by looking at previous posts. Just for starters, I am looking for two references. First a reference that proves that the use of radiative transfer models yields a proper numerical value for the radiative forcing for a doubling of CO2, according to the definition of radiative forcing in IPPC TAR to WG1 Chapter 6. Second a reference that proves that the only thing that matters in assessing the greenhouse effectiveness of CO2 is the radiation that is emitted at the top of the atmosphere. The details of this request go back to two previous requests for this information which you, glc, simply ignored.
|
|
|
Post by dmapel on Jun 8, 2009 16:57:36 GMT
jimcripwell, You might find this interesting: 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 μm 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.” Discussion that includes an analysis of a radiative forcing estimate that makes as much sense to this ignorant-denier-tool-of BIG OIL, as the IPCC’s guess. And here, several 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?” Just don’t let on to soclod that you are looking at skeptic blogs. He hates that.
|
|
|
Post by dmapel on Jun 8, 2009 17:14:41 GMT
There is something in there for you too steve. (I hope you are not still mad at me): www.junkscience.com/Greenhouse/What_Watt.htmlUpdate: New data contradicts aerosol cooling hypothesis: Atmospheric aerosols compete with carbon dioxide as an agent of warming. ... As much as half of the recent warming trend attributed to CO2 and other greenhouse gases is thought to have been cancelled out by cooling from aerosols. But new observations show that in some regions black carbon is as culpable as CO2 for the warming, and in some cases, has a greater effect. In a study published recently in Nature, Veerabhadran Ramanathan, an atmospheric scientist at the Scripps Institution of Oceanography in La Jolla, California, and colleagues, report that aerosols locked up in brown clouds over Asia are significant contributors to regional warming. 'Atmospheric brown clouds', which appear as a dark haze on the horizon, are formed from a cocktail of warming and cooling aerosols in the atmosphere. Once thought to be a local phenomenon, brown clouds that originate in urban centres from Los Angeles to Beijing are now known to travel thousands of kilometres, transported by air currents and high winds. "Brown clouds from the United States cover the Atlantic, the European brown cloud goes over central Asia, and China's brown cloud crosses the Pacific over to us," says Ramanathan. "We are each a back yard to someone else, and we're polluting every other person's back yard." Ramanathan and colleagues chose the Indian Ocean as the 'back yard' in which to study the warming effects of black carbon. In the winter and spring, heavily polluted air masses are transported over the Indian Ocean from central Asia, where the majority of black carbon is from cooking fires. Brown-cloud solar absorption usually takes place in the lower 3 km of the atmosphere and heats the atmosphere up to 5 km high. The scientists measured lower atmospheric heating in a 3-km-thick cloud layer over the Indian Ocean in March 2006 using 18 missions of three unmanned aerial vehicles (UAVs) launched from the island of Hanimaadhoo in the Maldives. Equipped with instruments to measure aerosol-particle concentrations and solar radiation, the UAVs were flown in a stacked manner, separated in height by only tens of metres and in time by less than ten seconds, making it possible to measure atmospheric heating rates directly. They found that the pollution cloud was responsible for 50% of the lower atmospheric heating, with the rest attributable to greenhouse gases. Taking a longer-term perspective using climate-model simulations, Ramanathan's team estimated warming in the lower atmosphere from both aerosols and greenhouse gases at about 0.25 °C a decade, sufficient to account for the retreat of the Himalayan glaciers. Because the Himalayan glaciers lie at such high altitudes, they are directly affected by the atmospheric warming effect from brown clouds, yet can also be influenced by soot deposition. Black carbon from aerosols eventually condenses out of the atmosphere and settles on ice and snow, significantly increasing the amount of sunlight that is absorbed. Researchers have recently found that the influence of black carbon on temperature and the melting of snow is three times greater than that of CO2 in Arctic regions. This new information shows us that aerosol emissions have both heating and cooling effects and, on balance, that aerosols are unlikely to have been 'hiding' anticipated enhanced greenhouse warming as claimed. The IPCC's 2007 Assessment Report 4 shows that models generally treat aerosols as strongly negative forcings (see adjacent graphic from AR4 Chapter 2, p136). Note that the uncertainty bars suggest potentially much greater cooling effect but zero potential for atmospheric warming...
|
|
|
Post by socold on Jun 8, 2009 18:35:08 GMT
I couldn't find a reference for the law of conservation of energy. If you can't find a paper that proves conservation of energy then how can you believe it is true? If none of the hundreds of experts on this forum can find a paper with empirical proof that "conservation of energy" exists then surely we can not assume such evidence exists. Indeed without such a paper being located we therefore know that the "IPCC models" are based on a false assumption of energy being "conserved" (which is ludicrous by the way if we consider the common meaning of the word "conserved") Did I mention the IPCC models are always wrong? They can't even get the earth is a sphere right and they have atmospheres made of lead. Completely totally wrong.
|
|
|
Post by glc on Jun 8, 2009 22:02:42 GMT
JimC
I have put this request before, as you can see by looking at previous posts. Just for starters, I am looking for two references. First a reference that proves that the use of radiative transfer models yields a proper numerical value for the radiative forcing for a doubling of CO2, according to the definition of radiative forcing in IPPC TAR to WG1 Chapter 6.
Let's leave the RF definition to one side for the moment and take things one step at a time. I assume you have read the Barrett link which discusses the Schwarzschild Equation given below
dI = -Ikr dz + Bkrdz
As Barrett writes, this calculates the transmission of radiation of a particular frequency through an absorbing medium.
Now then, Jim, do you have a problem with this equation. Is there anything you don't like about it. Is it this for which you need a reference?
Second a referene that proves that the only thing that matters in assessing the greenhouse effectiveness of CO2 is the radiation that is emitted at the top of the atmosphere.
Ok - do you remember in an earlier post I wrote that, for a roughly stable temperature, we must have
Incoming = Outgoing = ~235 w/m2
To which we can add
If Incoming > Outgoing the earth warms If Incoming < Outgoing the earth cools
Is there anything about any of these 3 statements with which you disagree?
|
|
|
Post by glc on Jun 8, 2009 22:26:34 GMT
You haven't shown me a single experiment that demostrates the atmosphere operates as you have described.
(A) We have the radiative transfer equations - do you agree? The results of these equations matches emission spectra as observed by satellites - do you agree?
(B) The radiative transfer equations calculate transmission at all 'layers' (i.e. at different pressures) of the atmosphere. So we can calculate transmission over, say, a few metres. Therefore we can fill a tube with N2, O2, and 300ppm CO2 and measure IR transmission directly. Then we can do the same with 600 ppm and again measure IR transmission.
Do you agree that if the measurements match the calculations AND the total atmosphere calculations (MODTRAN output) match the observed emission spectra there is a pretty good chance that the RT equations are able to represent IR transmission/absorption throughout the atmosphere. If not -why not?
You seem perfectly satisfied with a far less rigorous standard of experimentation, can you explain why? And how do you deal with the corrolary to all this that a bag of warm non-ghg gases out in space in a bag transparent to IR would never cool.
This all began when you maintained that N2 and O2 were as effective absorbers as CO2. I asked you what were the IR absorption bands for N2 and O2. You have not answered this - so I'll ask again. At what wavelengths do these gases absorb. It is important you answer this before we move on.
|
|