Greenhouse Thermodynamics and GCMs

The recent state of knowledge of global warming report released by the IPCC claims to have direct evidence of the enhanced greenhouse effect (EGE) responsible for global warming. In Chapter 3 Section 3.4 p40 of WG1 they make claims (1) the available data do not indicate a detectable trend in upper-tropospheric relative humidity, and (2) there is now evidence for global increases in upper-tropospheric specific humidity over the past two decades, which is consistent with the observed increases in tropospheric temperatures and the absence of any change in relative humidity.

Water in the upper atmosphere is important as, according to the theory, increases in greenhouse gases set off a positive feedback loop that amplifies the temperature increase, by increasing in water content in the warmer air and decreasing infared radiation is released to space. Notably, all global climate models (GCMs) show warming in the upper troposphere according to the EGE.

Now claims of direct evidence of the mechanism for global warming are particularly important, as they provide proof that increasing temperature is not due to some other mechanism. I have been looking into the veracity of this claim, here and here.

But despite the IPCC claims of no change to the relative humidity, the figure from the NCEP here shows it to be falling strongly, at all levels of the upper atmosphere and particularly in the upper troposphere (UT). A very readable paper by Minschwaner and Dessler (MD07) provides a clue. They show that while increasing temperature slightly increases water vapor and specific humidity (and thus a positive feedback increasing climate sensitivity to CO2 doubling), the amount is much less (-30%) that generally shown by the climate models that assume constant relative humidity. Their modelling shows that the increase in specific humidity is not enough to keep up with the amount needed to keep relative humidity constant for the increasing temperature, and so relative humidity falls. The paper says the models get it right about the positive feedback, but wrong about relative humidity, and so the effect is exaggerated.

While MD07 explains increasing specific humidity and falling relative humidity, and a positive feedback loop if temperature is increasing, does it provide evidence of the EGE as a cause of present day global warming? If temperatures and water vapor in the upper troposphere were actually increasing, while surface temperatures have been increasing, then this would provide the evidence for EGE they seek.

The problem is, temperatures in the upper tropospheres are not rising, as shown at the right hand side of the graph above, from Douglass et al. 2007. Despite claims by the IPCC of evidence of EGE, the only place where temperatures really rising in the upper troposphere is in the climate models themselves! The problem with rising temperatures with elevation, and erroneous constant humidity, is a double deviation from the actual observations!

Usually evidence of something means evidence in the real world, not evidence in a computer model.

Which brings me to another point — is there any evidence of EGE? While they claim small spectral differences demonstrate EGE, there are also other gaping inconsistencies between models, the literature and observations. For a start, the models assume constant relative humidity, MD07 claims this leads to exaggeration of CO2 sensitivity, and in the real world
relative humidity is decreasing. The same goes for UT temperature, and specific humidity. For there to be increased feedback, there has to be increased temperature. Reading the IPCC gives you the sort of uncomfortable feeling like a weather report that says it is sunny when its raining outside.

Two claims made in the IPCC Chapter 3 Section 3.4 p40 of WG1 are obviously false: (1) that the available data do not indicate a detectable trend in upper-tropospheric relative humidity, and (2) there is now evidence for global increases in upper-tropospheric specific humidity over the past two decades, which is consistent with the observed increases in tropospheric temperatures and the absence of any change in relative humidity.

Use of dubious evidence and false claims to support a theory indicates the degree of confirmation bias operating in global warming. Even though the science is contradictory, evidence of an enhanced EBE would be so convenient. It gives credibility to a whole raft of phenomena bundled up as anthropogenic global warming. It has the effect of leading the unwary to think that somehow the science is settled in this area, and there are no other possible explanations for recent warming. It may even lead to convictions! At least then it would go before people who differentiate models and reality.

  • kuhnkat

    Just hang on for a few more months. They will have “adjusted” the problem away. ;>)

  • kuhnkat

    Just hang on for a few more months. They will have “adjusted” the problem away. ;>)

  • http://rankexploits.com/musings lucia

    I bet you were wearing alligator loafers as you wrote that. :)

    This humidity issue is puzzling because the words in the document really don’t seem to match the figures easily available from NOAA. Since the AR4 doesn’t include any of their own, and only quotes results from papers, it’s difficult to quickly see the basis for the statements in the AR4. This means “off to the library”. (Or order the papers from the library.)

    It is a puzzlement though.

  • http://rankexploits.com/musings lucia

    I bet you were wearing alligator loafers as you wrote that. :)

    This humidity issue is puzzling because the words in the document really don’t seem to match the figures easily available from NOAA. Since the AR4 doesn’t include any of their own, and only quotes results from papers, it’s difficult to quickly see the basis for the statements in the AR4. This means “off to the library”. (Or order the papers from the library.)

    It is a puzzlement though.

  • Anonymous

    “it’s difficult to quickly see the basis for the statements in the AR4″

    Very diplomatically said Lucia. I am glad you find it incongruent as well.
    I know you lean towards the GHG warming explanation for warming, but I
    am having trouble finding any direct evidence for GHG warming now, except for a couple
    of fairly minor spectroscopic papers that would probably not stand scrutiny.

  • http://landshape.org/enm David Stockwell

    “it’s difficult to quickly see the basis for the statements in the AR4″

    Very diplomatically said Lucia. I am glad you find it incongruent as well.
    I know you lean towards the GHG warming explanation for warming, but I
    am having trouble finding any direct evidence for GHG warming now, except for a couple
    of fairly minor spectroscopic papers that would probably not stand scrutiny.

  • http://www.chriscolose.wordpress.com Chris Colose

    The Minschwaner observations only apply to very upper parts of the atmosphere; the OLR is sensitive to water vapor over a very deep layer. Upper atmospheric moistening is a source of uncertainty in terms of positive feedback, but the MD only treat a very small part of it, and so the conclusion that GCM’s underestimate the feedback cannot be drawn from that research.

    As for NCEP, there is very strong reason to suspect that the data is simply not reliable, especially before the satellite era. See the post in my blog, “Is the atmosphere drying up?”

  • http://www.chriscolose.wordpress.com Chris Colose

    The Minschwaner observations only apply to very upper parts of the atmosphere; the OLR is sensitive to water vapor over a very deep layer. Upper atmospheric moistening is a source of uncertainty in terms of positive feedback, but the MD only treat a very small part of it, and so the conclusion that GCM’s underestimate the feedback cannot be drawn from that research.

    As for NCEP, there is very strong reason to suspect that the data is simply not reliable, especially before the satellite era. See the post in my blog, “Is the atmosphere drying up?”

  • http://landshape.org/enm admin

    Hi Chris, Thanks for your response. As you seem to have some familiarity with the issue I welcome your contribution and potential resolution of this issue.

    I read your post, but it seems to just restate WG1 Sect. 3.4. Specifically I would welcome clarification of a number of apparent contradictions in the arguments:

    1. “there is very strong reason to suspect that the data is simply not reliable,”
    This doesn’t cut it. What is the confidence interval? Are they any worse than global average surface temperatures that also have changes in instrumentation? These data are averaged over many problematic measurements and still broadly useful.

    2. Sect 3.4 states: “that the available data do not indicate a detectable trend in upper-tropospheric relative humidity”. “available data” also includes radiosonde data. How do you account for what appears to be denying the existence of “inconvenient” data.

    3. Related to the above, the relative humidity trends look much more reliable at all altitudes than specific humidity.

    4. Though I haven’t really nailed down the levels of the atmosphere, without wanting to get into ambiguity over that, the levels they model at 200-300hPa are the same levels that models are supposed to exhibit maximum EGE warming. See the figure from Douglass above. Therefore this is exactly the region that should be identified for evaluating the accuracy of GCM modeling of enhanced greenhouse due to feedbacks.

    5. The spectroscopic effects are very small, and the stats suspect. See my post on the Harries paper here http://landshape.org/enm/interpretation-bias/ and John Daly extensive review http://www.john-daly.com/smoking.htm. I haven’t read Sodon’s paper yet.

    Sorry to seem like I am hammering on this. I really would appreciate clarification, and we try to be civil around here. Regards.

  • http://landshape.org/enm admin

    Hi Chris, Thanks for your response. As you seem to have some familiarity with the issue I welcome your contribution and potential resolution of this issue.

    I read your post, but it seems to just restate WG1 Sect. 3.4. Specifically I would welcome clarification of a number of apparent contradictions in the arguments:

    1. “there is very strong reason to suspect that the data is simply not reliable,”
    This doesn’t cut it. What is the confidence interval? Are they any worse than global average surface temperatures that also have changes in instrumentation? These data are averaged over many problematic measurements and still broadly useful.

    2. Sect 3.4 states: “that the available data do not indicate a detectable trend in upper-tropospheric relative humidity”. “available data” also includes radiosonde data. How do you account for what appears to be denying the existence of “inconvenient” data.

    3. Related to the above, the relative humidity trends look much more reliable at all altitudes than specific humidity.

    4. Though I haven’t really nailed down the levels of the atmosphere, without wanting to get into ambiguity over that, the levels they model at 200-300hPa are the same levels that models are supposed to exhibit maximum EGE warming. See the figure from Douglass above. Therefore this is exactly the region that should be identified for evaluating the accuracy of GCM modeling of enhanced greenhouse due to feedbacks.

    5. The spectroscopic effects are very small, and the stats suspect. See my post on the Harries paper here http://landshape.org/enm/interpretation-bias/ and John Daly extensive review http://www.john-daly.com/smoking.htm. I haven’t read Sodon’s paper yet.

    Sorry to seem like I am hammering on this. I really would appreciate clarification, and we try to be civil around here. Regards.

  • http://www.chriscolose.wordpress.com Chris Colose

    admin,

    the issues with the reanalysis data are extensively discussed in IPCC Chapter 3 as you noted, as well as the supplementary information available online, and in references therein. Without opening up some links (I’m going to bed now, sorry), I don’t want to give numbers off of the top of my head, but based on the IPCC’s discussion of humidity trends in the upper atmosphere (and my own personal correspondence with Soden, where he uses the term “useless”) it can’t be too good. On the flipside, I can’t just create a graph with random numbers and then ask people why it is wrong, I need to demonstrate with some degree of confidence that I am right…and we cannot now do that with the older data, and even with reanalysis data post-satellite era. Surface-air temperatures are a different climatic variable, and one that I put a lot of confidence in for older data given a relaible global instrumental record after 1850. Still, even this has some problems including SST measurements and southern hemispheric data.

    Actually, MD just look around 11 to 14 kilometers from the surface of the Earth and just in the tropics. The overall contribution here is quite small. See Soden and Held 2000. You can also find various quotes around the internet from scientists like Lindzen, Sherwood, Pierrehumbert, and others agreeing with that (NASA has a good page if you google the authors names)

    I do not read sites like “john-daly.com” so if there is something in the literature you want to discuss, I will see what they have to say. I wouldn’t be surprised to see the magnitude of the WV feedback slightly altered as time goes on given the uncertanties of the contributions in the upper atmosphere, but it is hard to reconcile the 20th century record or the paleoclimatic record with a WV feedback significantly less than we think.

  • http://www.chriscolose.wordpress.com Chris Colose

    admin,

    the issues with the reanalysis data are extensively discussed in IPCC Chapter 3 as you noted, as well as the supplementary information available online, and in references therein. Without opening up some links (I’m going to bed now, sorry), I don’t want to give numbers off of the top of my head, but based on the IPCC’s discussion of humidity trends in the upper atmosphere (and my own personal correspondence with Soden, where he uses the term “useless”) it can’t be too good. On the flipside, I can’t just create a graph with random numbers and then ask people why it is wrong, I need to demonstrate with some degree of confidence that I am right…and we cannot now do that with the older data, and even with reanalysis data post-satellite era. Surface-air temperatures are a different climatic variable, and one that I put a lot of confidence in for older data given a relaible global instrumental record after 1850. Still, even this has some problems including SST measurements and southern hemispheric data.

    Actually, MD just look around 11 to 14 kilometers from the surface of the Earth and just in the tropics. The overall contribution here is quite small. See Soden and Held 2000. You can also find various quotes around the internet from scientists like Lindzen, Sherwood, Pierrehumbert, and others agreeing with that (NASA has a good page if you google the authors names)

    I do not read sites like “john-daly.com” so if there is something in the literature you want to discuss, I will see what they have to say. I wouldn’t be surprised to see the magnitude of the WV feedback slightly altered as time goes on given the uncertanties of the contributions in the upper atmosphere, but it is hard to reconcile the 20th century record or the paleoclimatic record with a WV feedback significantly less than we think.

  • http://landshape.org/enm admin

    FYI from Lubos: “But I found it so insightful that you might enjoy it, too. It discusses the importance of feedbacks, why most of them are negative, and what contrived things you have to assume if you want to believe that climate sensitivity significantly exceeds 1 °C.”

    http://motls.blogspot.com/2008/06/coyoteblog-dont-panic.html

  • http://landshape.org/enm admin

    FYI from Lubos: “But I found it so insightful that you might enjoy it, too. It discusses the importance of feedbacks, why most of them are negative, and what contrived things you have to assume if you want to believe that climate sensitivity significantly exceeds 1 °C.”

    http://motls.blogspot.com/2008/06/coyoteblog-dont-panic.html

  • Andrew

    Chris Colose said
    “it is hard to reconcile the 20th century record or the paleoclimatic record with a WV feedback significantly less than we think.”

    This claim just won’t die, will it?
    http://www.agu.org/pubs/crossref/2008/2007GL032759.shtml
    http://www.agu.org/pubs/crossref/2007/2007JD008740.shtml

  • Andrew

    Chris Colose said
    “it is hard to reconcile the 20th century record or the paleoclimatic record with a WV feedback significantly less than we think.”

    This claim just won’t die, will it?
    http://www.agu.org/pubs/crossref/2008/2007GL032759.shtml
    http://www.agu.org/pubs/crossref/2007/2007JD008740.shtml

  • http://landshape.org/enm admin

    #8 Yes, and these and similar arguments are only indirect. Here I am looking for the direct evidence of EGE that the IPCC claims it has, but any direct evidence will do. Indirect evidence always allows other explanations.

    It is striking to me that all of the article laying out the argument for CO2 warming, like
    Dr. Tapio Schneider
    in Skeptic Magazine lay out indirect evidence, but only make assertions when it comes to direct evidence. They would have to do that if there was no direct evidence of AGW.

    The opinion of Dr Sodon on the matter is not direct evidence. The spectroscopic measurements the IPCC claims are the crucial direct evidence of increased feedback are from Sodon’s own work, and he is the lead author on the chapter, so he could not be regarded as impartial judge of the importance of his own work.

  • http://landshape.org/enm admin

    #8 Yes, and these and similar arguments are only indirect. Here I am looking for the direct evidence of EGE that the IPCC claims it has, but any direct evidence will do. Indirect evidence always allows other explanations.

    It is striking to me that all of the article laying out the argument for CO2 warming, like
    Dr. Tapio Schneider
    in Skeptic Magazine lay out indirect evidence, but only make assertions when it comes to direct evidence. They would have to do that if there was no direct evidence of AGW.

    The opinion of Dr Sodon on the matter is not direct evidence. The spectroscopic measurements the IPCC claims are the crucial direct evidence of increased feedback are from Sodon’s own work, and he is the lead author on the chapter, so he could not be regarded as impartial judge of the importance of his own work.

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