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How do we know CO2 is causing warming?

Posted on 8 October 2009 by John Cook

We've just perused the empirical evidence that humans are raising atmospheric CO2 levels. In earlier posts, we noted that tallying up the planet's heat content shows that our climate is accumulating heat, proof of global warming. But is there any evidence that links the two? Is there empirical data proving that increased CO2 contributes to the energy imbalance that causes global warming?

The greenhouse gas qualities of CO2 have been known for over a century. In 1861, John Tyndal published laboratory results identifying CO2 as a greenhouse gas that absorbed heat rays (longwave radiation). Since then, the absorptive qualities of CO2 have been more precisely measured and quantified by laboratory results and radiative physics theory (Herzberg 1953, Burch 1962, Burch 1970, etc).

Satellite measurements of the change in outgoing longwave radiation

So according to lab results and radiative physics, we expect that increasing atmospheric CO2 should absorb more longwave radiation as it escapes back out to space. Has this effect been observed? The paper Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997 (Harries 2001) attempts to find out. In 1970, NASA launched the IRIS satellite that measured infrared spectra between 400 cm-1 to 1600 cm-1. In 1996, the Japanese Space Agency launched the IMG satellite which recorded similar observations. Harries 2001 compared both sets of data to discern any changes in outgoing radiation over the 26 year period. The resultant change in outgoing radiation was as follows:


Figure 1: Change in spectrum from 1970 to 1996 due to trace gases. 'Brightness temperature' indicates equivalent blackbody temperature (Harries 2001).

What they found was a drop in outgoing radiation at the wavelength bands that greenhouse gases such as CO2 and methane (CH4) absorb energy. The change in outgoing radiation over CO2 bands was consistent with theoretical expectations. Thus the paper found "direct experimental evidence for a significant increase in the Earth's greenhouse effect".

This result has been confirmed by subsequent papers using the latest satellite data. Griggs 2004 compares the 1970 and 1997 spectra with additional satellite data from the NASA AIRS satellite launched in 2003. Chen 2007 extends this analysis to 2006 using data from the AURA satellite launched in 2004. Both papers found the observed differences in CO2 bands matched the expected changes based on rising CO2 levels. Thus we have empirical evidence that increased CO2 is preventing longwave radiation from escaping out to space.

Measurements of downward longwave radiation

What happens to longwave radiation that gets absorbed by greenhouse gases? The energy heats the atmosphere which in turn re-radiates longwave radiation. This re-radiated energy goes in all directions. Some of it makes its way back to the surface of the earth. Hence we expect to find increasing downward longwave radiation as CO2 levels increase.

Philipona 2004 finds that this is indeed the case - that downward longwave radiation is increasing due to an enhanced greenhouse effect. Evans 2006 takes this analysis further. By analysing high resolution spectral data, the increase in downward radiation can be quantitatively attributed to each of several anthropogenic gases. The results lead the authors to conclude that "this experimental data should effectively end the argument by skeptics that no experimental evidence exists for the connection between greenhouse gas increases in the atmosphere and global warming."

So we have multiple lines of empirical evidence for CO2 warming. Lab tests show CO2 absorbing longwave radiation. Satellite measurements confirm that less longwave radiation is escaping to space. Surface measurements detect increased longwave radiation returning back to Earth at wavelengths matching increased CO2 warming. And of course the result of this energy imbalance is the accumulation of heat over the last 40 years.

Acknowledgements: A big thanks must go to AGW Observer. Their lists of papers on changes in outgoing longwave radiation, changes in downward longwave radiation and laboratory measurements of CO2 absorption properties made this post possible.

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Comments 151 to 200 out of 230:

  1. yes, it does appear that there are two papers by Harries relating to this same data set! thanks for clarifying. But my question i have goes for both. when you look at the raw data, the IR wavelengths that should be absorbed by CO2 (corresponding to the 700waves/cm) you'll see that 1997 had more emission of this IR frequency than 1970. when you look at the 'simulated' results then you see graphs like you display. why are the massaged, biased, simulated graphs of more value than the actual measurements? that is really my question - i'm sure there is a good reason but i'm not up to par with the authors here and had a hard time following the paper when they talked about adding in biases for SST and water vapor. agreed that temperatures and humidity for 1997 and 1970 (Apr-Jun) were probably very different but i don't see why we need to artificially bias the data to account for that. thanks in advance for your help!
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    Response: These are good questions - when I first read the paper, I asked the author (John Harries) similar questions.The simulated graphs are not of more value than observed data - they are compared to observations to confirm the veracity of their simulations (successfully). Given that the simulated change in spectrum matches so closely with the observed data, this enables the authors to filter out temperature and humidity effects, thus displaying the exact effect due to trace-gases only.

    Note - the enhanced greenhouse effect is also confirmed by surface measurements of downward IR radiation. Independent confirmation from completely separate sets of observed data are always the ideal result.
  2. ok, thanks for clarifying. i'm sorry for the confusion on the multiple articles and i apologize if my comments might be construed by others that you were 'making up' the graphs. that was not the purpose of my post. i was confused and wanted clarification. i know you didn't take it that way but just in case people come around and read this later, i wanted my intent clearly spelled out here.

    so if i understand you right, since 1997 was warmer and contained more water vapor, then that is why most of the IR showed increased emissions vs. 1970. if that is true, why? if the surface temperatures were warmer that just means that the black body radiation curve peak frequency shifts a little higher (and peak wavelength shift lower) but i would expect the magnitude or intensity to remain the same. and shifting that peak wavelength would mean moving further away from the 15um wavelength that CO2 absorbs.

    sorry if this is elementary stuff for you and if there is a site that explains this in more detail you can paste a link and i'll go do my homework.
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  3. J COOK say: "Pielke isn't disputing the results of Philipona 2004 - I suggest you read the post you link to."

    ????????

    http://pielkeclimatesci.wordpress.com/2009/09/29/observational-evidence-of-a-change-of-surface-radiative-forcing-in-a-paper-philipona-et-al-2004/

    "This paper (Philipona 2004) documents that changes of 1 Watt per meter squared (or more) in the longwave fluxes that we examined in Pielke and Matsui (2005) are realistic. The Klotzbach-Pielke et al. (2009) paper demonstrates that a significant bias is introduced in the land portion of the global surface temperature trend which is used in the assessment of global warming, that can be explained, at least in part, due to such changes in longwave radiative fluxes at night"
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  4. clayco,
    the meaning looks pretty clear. "changes of 1 Watt per meter squared (or more) in the longwave fluxes that we examined in Pielke and Matsui (2005) are realistic" because it has been found by Philipona et al to be 1.8 W/m2. So it's quoted in support of their number. No sign of dispute at all.
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  5. In another thread, TimTheToolMan said this: "If a year or especially six years are cool then that needs to be explained because if it cant be explained within the framework of AGW theory then AGW theory is broken."

    ...or, as the recent P&J study shows, OHC as it's currently measured doesn't show the whole picture.

    I don't see any reason to think a single year is indicative of any kind of trend. On the contrary (as CBD pointed ou), it is a shining example of cherry-picking, and no amount of out-of-context quotes from Ternberth is going to change this.
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  6. TTTM wrote on another thread:

    "I cant explain this issue [that we should be able to make a direct causal link between CO2 levels and ocean heat content?] easily. It involves a lot of background knowledge and anyone truely interested in this can take it from the initial references I've provided.

    By "the rate observed", I'm talking about the increases in OHC observed over the last few decades. AGW theory attributes this heating to the radiative imbalance caused by Anthropogenic CO2."


    Actually the scientific literacy on this blog is quite high, so the fact that you can't explain it "easily" is not a problem. Except perhaps with the quality of your explanation. Please give it a go.
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  7. The RealClimate article to start with is this one

    The upshot of this is that they acknowledge that CO2 doesn't directly heat the oceans and theorise that instead it causes them to cool more slowly.

    So they devise an experiment to show how increased downward LW radiation changes the temperature of the ocean's cooler skin with the suggestion that will result in decreased heat flux.

    Their experiment does indeed measure a change in skin temperature but uses the much larger effect of cloud induced downward LW radiation which is of the order of 100W. Compare this to CO2 increase which might account for a few Watts.

    And their result was a small but measurable effect with the 100W cloud effect.

    So what hasn't the science covered?

    Firstly the effect explored was more than an order of magnitude greater than the effect of CO2 and secondly the change in skin temperature wasn't attempted to be related to changes in LW heat loss from the ocean at all.

    So basically "science" has come up with a theory for ocean heat loss decrease due to increased CO2, showed that in principle an effect exists...and stopped. It has no idea whether the effect of CO2 is sufficient to explain the accumulation of heat in the oceans.

    At least none I ever found...
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  8. TTTM #157

    I find it strange that the RealClimate article you refer to makes the conclusion that:

    "To conclude, it is perfectly physically consistent to expect that increasing greenhouse gas driven warming will heat the oceans – as indeed is being observed."

    Which is the opposite of yours. It appears to me from a fairly superficial reading that you are misinterpreting the quasi-experiment.

    Cloud cover is used as a covariate with CO2 in order to control for the effect of greenhouse gasses on ocean heating. This is in the absence of being able to do a real experiment. As a result you seem to be describing the behaviour of the "control" condition (to the extent that a control condition can exist in this type of experimental work) to make your conclusion.

    However this is not my area of expertise and I will defer to others with a better understanding of this part of the science.
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  9. Perhaps you should do more than a superficial reading before commenting on my understanding of the experiment.

    My conclusion is precisely the same as theirs.

    "So basically "science" has come up with a theory for ocean heat loss decrease due to increased CO2, showed that in principle an effect exists"

    The difference is that they've described their conclusion in the best possible light and entirely glossed over the fact that they only have half the story and dont know whether the effect actually accounts for the ocean warming.
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  10. Bingo, TTTM! Reduced rate of heat loss! Now, just think, "With the same amount of heat gain as before the change in heat loss." If you can understand those two things working together, you understand the whole thing.
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  11. Its not a question of understanding, Doug. Its a question of the numbers. Science doesn't have any (that I'm aware of) and so doesn't actually know whether CO2 is responsible for ocean heating at all.
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  12. I'm a slow learner, I forgot that "Tim the Tool, Man" is his own ultimate authority on the behavior of the climate and thus it's pointless trying to tell him anything. Oops.
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  13. You would have my gratitude if you could point me to the paper that quantifies the effect described in the RealClimate article and thereby validates the AGW theory as relates to ocean warming due to Anthropogenic CO2.
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  14. I won't have anything but regret over wasting more time if I bother to do that, TTT,M.

    Find somebody else to pester. I'm sure they'll be along soon enough.
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  15. TTTM #163

    There is a flaw in your premise here. You appear to be attempting to differentiate the heat caused by CO2 as opposed to any other greenhouse gas. This part of your argument appears to violate the laws of physics, as heat is heat is heat regardless of its source.

    This failure to obey the laws of physics (or more charitably, mis-explanation of the phenomenon under examination) is a serious distraction from the rest of your argument, which appears to be at odds with the mainstream scientific interpretation of the phenomenon under investigation.

    Perhaps you should show us "the numbers" clearly and concisely (i.e. show us explicitly model versus observed) so that we can assess your claims. If you want people to accept your argument you need to do the groundwork to make it easy for them to do so :)
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  16. " You appear to be attempting to differentiate the heat caused by CO2 as opposed to any other greenhouse gas."

    You're going to have to explain what you mean here because I'm not differentiating anything as far as I'm concerned.

    So far, I've described the article and said they dont have any numbers to back up their theory.

    Please be specific about what you disagree with.
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  17. TTTM #116

    You attempted to make a causal link too far here. So I think there's a typo in your comment, it should read: "I'm going to have to explain what I mean because it's clearly not well explained".

    Presumably you have numbers to back up your hypothesis? I'm indicating that the clarity of your explanation is poor, and it counfounds at least two independent issues. Also your confusion of the word "theory" with what you presumably mean to be "hypothesis" suggests that you need to work on your position more in order to express youreself more clearly.
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  18. If such a person as TTT,M really cared to have an answer as opposed to argue, he'd start by going to the literature and usually would never show up on SkS. It's diagnostic of a person interested in pointless argumentation that they show up here repeatedly demanding answers they'd do better to seek out for themselves.

    As an example, here's a paper from long ago, with a citation trail extending in two different directions on the timeline, which if followed will eventually sort out TTT,M's hermetically conserved disputation:

    Thermodynamic regulation of ocean warming by cirrus clouds deduced from observations of the 1987 El Nino

    Notice, there's no way SkS can reproduce the level of detail conveyed in that double-ended trail of cites. TTT'M's favored rhetorical method is to demand that the folks at this site behave as perfect proxies for people who do research in the various fields he's not interested in. It's a old, tired technique. It's also conspicuous-- once we notice-- that TTT,M spends more time and effort badgering people at this site than seeking answers on his own, in a rich literature freely available.

    Unfortunately, the articles posted at this site necessarily leave some ambiguity hanging in the air, because full understanding of the topics covered here requires a level of specialist knowledge in the hands of remarkably few people, with the collective knowledge of all related topics beyond the reach of any single person. As well, presenting a case durable against a person infected with distrust requires detail beyond what's useful for most people. Folks like TTT,M exploit this, for whatever reason.

    This asymmetry works in two directions, however. For instance, TTT,M says, "Its a question of the numbers. Science doesn't have any (that I'm aware of) and so doesn't actually know whether CO2 is responsible for ocean heating at all. Notice that TTT,M is substituting his and our lack of expertise on this subject for an argument, when in point of fact experts don't agree with him.

    It's crucial to discern when "I doubt it" is being positioned as an argument. When we have a choice between "I doubt it" and what an actual expert says, it's generally better to go with the expert.

    This is not fundamentally a fair fight or even a fight at all. On one side is TTT,M and on the other the scientific community. The thing that allows TTT,M to obtain his stimulation here is that--of course-- SkS is not designed to deliver a postgraduate-level education on dozens of different fields related to climate change. So to that extent that's true, SkS will always be prey to silly distractions like TTT,M.
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  19. doug:

    Thanks for pointing TTTM in the right direction regarding the literature. I've been trying to encourage him to start looking in more detail, as it's clearly unreasonable for me or anyone else to do his work for him :)
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  20. Hopefully TTTM will stop wasting everyone's time and start actually learning the science, but somehow I doubt it. :-/
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  21. "If such a person as TTT,M really cared to have an answer as opposed to argue, he'd start by going to the literature and usually would never show up on SkS."

    You know nothing about me and nothing about what I have researched on this topic. The fact I brought it up at all ought to indicate that I know something about it.

    You've made an unprovoked ad hominem attack on me and have obliquely tried to imply the science is solid even though you provide no data to support that position.

    I do appreciate the link you've provided and my initial reading indicates that the issue is not addressed by this paper. It will take me some time to go through the references.

    I HAVE researched this topic and read a large number of papers looking for the answer. Not for some time though. I gave up a while back. I genuinely am looking for an answer.

    At this point I am a skeptic for good reason. As far as I'm concerned AGW theory is inadequate.
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  22. TTT,M, if you were making some specific argument against some specific thing, my speculations about your appearance here might be an "ad hominem attack." However, as you've not made an argument to address, such a thing is impossible, ipso facto.

    That is, unless we're prepared to accept "I doubt it" as an argument, which I don't.

    Arguably, being a "skeptic" does not entail maintaining a posture of ignorance while demanding to be educated.
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  23. My argument is very specific. My argument has been well defined and relates specifically to CO2 warming the oceans as opposed to other skeptic's arguments of CO2 warming at all. Or the extent of warming or whatever.

    You say I'm ignorant but I say I've researched this and not found an answer. If such an answer exists then all you need to do is find it and AGW theory remains intact.

    I am of the opinion, however, that an answer simply doesn't exist in the science today.
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  24. @TTTM: "My argument has been well defined and relates specifically to CO2 warming the oceans as opposed to other skeptic's arguments of CO2 warming at all."

    This sentence perfectly illustrates how misguided your whole research has been, and why you have allegedly not found an answer for the inexistent issue.

    Greenhouse forcings, together with all other forcings, heat the oceans. CO2 captures then redirects heat in a random direction, and sometimes that is absorbed by the oceans, but the mechanism of absorption is the same whether the heat is coming straight from the sun, or is being re-radiated by CO2, CH4, WV, etc.

    "You say I'm ignorant but I say I've researched this and not found an answer."

    Perhaps that's because you really haven't found the question either. All you know is that, somehow, it must show that AGW is inadequate...
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  25. TTTM, you're not making a specific argument, you're only saying that you don't agree with something specific, namely that oceans are susceptible to having their temperature changed as a result of exposure to IR radiation.

    This is not an argument:

    "I am of the opinion, however, that an answer simply doesn't exist in the science today."

    An argument would consist of your showing how oceans are immune to having their temperature changed by IR radiation.

    Also, I've not said you're ignorant. I said you're adopting a posture of ignorance, but I'll grant that's going too far; it's possible you simply don't understand the generic nature of IR radiation and are thus confused about how increased C02 in the atmosphere could increase the temperature of the ocean. By your own word, you don't doubt there's an enhanced "greenhouse" effect in play, so assuming you're not ignorant, the matter really does come down either to posturing or confusion.
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  26. "An argument would consist of your showing how oceans are immune to having their temperature changed by IR radiation."

    That would be one argument. Its not my argument however. My argument is that science doesn't have any data on the magnitude of the effect for CO2. Therefore Science cant actually say whether CO2 is warming the oceans or not.

    It comes back to one of my earlier statements where I'd said science observes ocean warming and automatically attributes it to CO2 without having any quantifiable justification.

    Compare this to the work that has been done to justify CO2's feedback mechanisms and consequent increases in downward LW radiation resulting in measurable increases in temperature in the atmosphere and on land.
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  27. "; it's possible you simply don't understand the generic nature of IR radiation and are thus confused about how increased C02 in the atmosphere could increase the temperature of the ocean."

    Suffice to say that its me thats done the research here and so I think I know the implications. Your comment of "generic nature" indicate that you dont understand the issue at all.

    One thing is certain, I didn't make this up. There is an article on RC that clearly describes the problem and the experiment that attempts to explain the solution.

    In arguing there is no problem you're dismissing the article on RC.
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  28. @TimTheToolMan: It is not CO2 that warms the ocean, but IR radiation. We know how much of that IR radiation is coming back down to the surface. Some of that IR radiation ends up on land, some ends up in the oceans.

    "My argument is that science doesn't have any data on the magnitude of the effect for CO2."

    Sure we do: about 3 degrees for doubling the CO2 concentration in the atmosphere.
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  29. @TTTM: "In arguing there is no problem you're dismissing the article on RC."

    Wait a minute...*you're* dismissing the article on RC. Does that mean you also think there is no problem?
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  30. "Wait a minute...*you're* dismissing the article on RC. Does that mean you also think there is no problem?"

    No, I'm pointing out the limitations of the experiment and lack of taking the result further in the science to actually justify the warming.
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  31. Citing the article at RealClimate only deepens the mystery of what you're trying to accomplish, TTTM.

    You also sound rather ridiculous when you say the article is bereft of a useful conclusion, or numerical analysis in support of their conclusion.

    You:

    I've described the article and said they dont have any numbers to back up their theory.

    RealClimate:



    How about describing, in detail, what parts of that article you disagree with? Specifically, what's wrong with their method? What's faulty about the analysis? Most importantly, you need to show how the IR emanating from clouds is different from IR from other sources, because that's the crux of your argument. The amount of IR is not the issue, it's the mechanism you appear to doubt, but you need to show how. Be specific, because saying "I don't agree" is not an argument.
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  32. @TTTM: "No, I'm pointing out the limitations of the experiment"

    What limitations are these, again?
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  33. archiesteel #182:

    I think these are the limitations where he's confused the control variable and the experimental variable :)
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  34. " The amount of IR is not the issue, it's the mechanism you appear to doubt"

    And where do you get that idea from? It is precisely the amount of IR that is one of the the problems. The CO2 effect is more than an order of magnitude smaller than the LW radiation explored in the experiment using LW from clouds.

    The other problem I have with the article is that the graph that you have reposted shows the skin temperature change as a result in LW radiation changes but how much LW radiation reduction from the ocean does that imply? See the above comment for additional uncertainty.

    That side of the theory is completely unexplored.

    I cant say this any other way, you either understand my argument or you need to reread the article until you understand the issue.
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  35. On a parenthetical note, TTTM is not actually attempting to argue w/RealClimate, he's in dispute w/Peter Minnett.
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  36. @TTTM: "The CO2 effect is more than an order of magnitude smaller than the LW radiation explored in the experiment using LW from clouds."

    This doesn't matter. The article is about the relationship between IR radiation and upper sea level temperatures. Demonstrating the relationship was the goal of the article, not the amount of downward LW radiation produced by CO2's greenhouse effect.

    The author of the article acknowledges this at the end:

    "Of course the range of net infrared forcing caused by changing cloud conditions (~100W/m2) is much greater than that caused by increasing levels of greenhouse gases (e.g. doubling pre-industrial CO2 levels will increase the net forcing by ~4W/m2), but the objective of this exercise was to demonstrate a relationship."

    I'm sorry, but you have failed to demonstrate in any way how the article is wrong, or why this would impact AGW theory. Until you come up with new arguments to support your hypothesis, you'll have failed to convince me (and others here) of its validity.
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  37. I've no doubt my argument fails to convince you archiesteel.
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  38. @TTTM: And why is that? Please elaborate.
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  39. TTTM #187

    That will be because you have not demonstrated that your argument has any validity.
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  40. It is precisely the amount of IR that is one of the the problems. The CO2 effect is more than an order of magnitude smaller than the LW radiation explored in the experiment using LW from clouds.

    Well, at least we've confirmed the the crux of your misunderstanding. Some progress is possible!

    ...how much LW radiation reduction from the ocean does that imply?... That side of the theory is completely unexplored.

    Oh, you didn't read the Ramanathan article above? I could swear you said you did. Anyway, check the literature; maximum sea surface temperature investigations have been going on for at least 40 years. Not exactly "completely unexplored," more just a matter of unknown to you. That's a nice example of why expertise and experience counts for a lot, and why you'd never find the likes of me blithely disagreeing with people like Minnett.
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  41. "Well, at least we've confirmed the the crux of your misunderstanding."

    What? I believe this is your misunderstanding. I'll explain in more detail.

    The experiment used clouds cover to measure the effect of the skin. Clouds mean that there is about 100W of increased downward LW radiation seen at the sea surface.

    Compare this to the CO2 effect which is stated in the article as being 4W for a doubling of CO2 and is closer to 3W for current increases since industrialisation.

    So the effect they measured using clouds to create changes in downward LW radiation was 33 times greater than the effect that CO2 has on the ocean surface.

    "Oh, you didn't read the Ramanathan article above? I could swear you said you did. Anyway, check the literature; maximum sea surface temperature investigations have been going on for at least 40 years."

    I have read it and there is no analysis of how increased downward LW radiation from CO2 effects the amount of energy the ocean radiates.

    For that matter there isn't even an analysis of increased LW radiation from clouds and what effect that has on decreased radiation from the ocean.

    If you believe there is then please point it out.
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  42. TTTM #191

    So are you saying that there is no evidence for this extra 10% of downward longwave radiation that should be accounted for by CO2? Or are you saying the experimental model is not sensitive enough to detect this. If the former, you need to show the evidence. If the latter, then we're screwed and specialists should be devising more sensitive data collection methods. The second of these conclusions is not sufficient to provide evidence against anthropogenic global warming mind you, so take care.
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  43. TimTheToolMan at 16:26 PM, I'm finding this an interesting discussion.
    What I am left wondering is where is the evaporation process being accounted for whilst the measurements of the temperature gradient of the skin layer were being taken, in particular as the cloud cover varied.
    I know it is not mentioned in the article, is it simply not relevant or merely given time out?
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  44. Neither kdkd

    The experiment was designed to explore sea surface temperature changes as a result of changes in downward LW radiation. It succeeded in that for the relatively large downward LW radiation changes imposed by clouds.

    But thats all its done. The next step has to be how those sea surface temperature changes relate to changes in the loss of energy from the ocean. This needs to be be done quantitatively so that the CO2 effect can be seen to be sufficient to cause the observed warming.
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  45. @johnd

    re: Evaporation. Its a very good question and represents another shortcoming of the experiment.
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  46. Tim, I've changed my mind. You are confused and I apologize for all my wild speculation earlier.

    The experiment described by Minnett was a means of verifying the controlling mechanism and efficacy of downward IR radiation warming the ocean. It has nothing to do with the intensity of the radiation. Reducing the intensity of the downward radiation does not change how it interacts with sea water. Can you see that? I hope so.

    Meanwhile, the Ramanathan article addresses both radiation from clouds as well as radiation from the sea surface, in a comprehensive way. The article has to treat the various inputs and outputs of sea surface temperature comprehensively because it's establishing a case for ultimate limits on sea surface temperature. Ironically, that article is the nearest approximation to explaining how oceans might warm less than would simplistically seem the case that you're likely to find, something resembling the sort of argument you're failing to offer. I specifically tried to find something along the lines of what you were speaking of w/regard to unobvious limits to ocean temperature; Ramanathan suggesting support for your hypothesis is a gift. How you could possibly miss that is difficult to understand.
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  47. Johnd, I highly recommend diving into a reasonably broad paper and following cites forwards and backwards. As I mentioned, the Ramanathan paper is an excellent place to start because of its sweeping objectives.
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  48. "It has nothing to do with the intensity of the radiation."

    The only relevence to intensity of radiation is as relates to the fact the experiment measures SSTs relating to 100W downward LW radiation whereas CO2 only supplies 3W.

    The experiment therefore exagerates the effect.

    "Reducing the intensity of the downward radiation does not change how it interacts with sea water."

    Of course it does. Less downward LW radiation causes less of a warming effect. The graph you posted clearly shows that.

    Perhaps you need to take a step back. Do you agree with the RC article and acknowledge that there is an issue with ocean warming from CO2 at all?
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  49. Let's try again.

    It's mechanism that's talked of by Minnett, not intensity, Tim. The experiment does not exaggerate the the IR, it has nothing to do with intensity, rather it exploits a source of IR sufficiently powerful as to produce a usable signal to investigate the mechanism controlling skin temperature. Minnett does not suggest that C02 is going to cause such a powerful flux because of course he's not investigating the intensity of the flux.

    Can anybody else think of a way to explain this to Tim?

    How about an analogy. You want to investigate if a desk lamp is capable of warming an area on your desk. You shine a desk lamp on your desk from 12" away and find that the area under the lamp warms. If you'd chosen to shine the lamp at the desk from 24" away and found that your desk warmed in the illuminated area, would that have changed your opinion about how the desk warmed?
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  50. TTTM #191: "So the effect they measured using clouds to create changes in downward LW radiation was 33 times greater than the effect that CO2 has on the ocean surface."

    Clouds are localized and temporary. CO2 increases are global and persistent.

    So sure... let's say individual cloud at a specific location might cause 33 times as much warming as the CO2 at that location alone. That cloud won't always be there... and it doesn't cover the entire planet. Further, clouds are formed from water vapor... which increases in the atmosphere as the temperature goes up... which increasing CO2 is causing to happen. So you've got increased CO2 warming + increased water vapor warming + increased cloud warming... all triggered by rising CO2 levels.
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