Models versus satellites

A graph that is fairly commonly promoted to – apparently – illustrate that models and observations have diverged, is one produced by John Christy which compares models to satellite/balloon data for the troposphere. Ignoring all the potential issues with this graph, one problem is simply that it has never really been explained fully; until now that is. Gavin Schmidt has just completed a post on Realclimate called Comparing models to the satellite datasets.

Credit: Gavin Schmidt

Credit: Gavin Schmidt

I don’t really need to say much more, because you should really read Gavin’s post. What I did want to say is that it is a masterclass in how to present and discuss scientific evidence. It steps through all the different choices one can make when doing something like comparing model results and observations. I was, however, wanting to just highlight the figure on the right. Essentially you need to decide how to align your different model runs; do you normalise them with respect to a single year, some average over a number of years, or with respect to the trends. The figure on the right shows what happens if your baseline is 1 year (1979), 4 years (1979-1983), 10 years (1979-1988), or if you force the trend lines to all pass through the same point (the x-axis in 1979).

As you can see, there is quite a difference, both in terms of the apparent mean trend and also the 95% spread. Gavin’s argument (which makes sense to me) is that if you want to enhance the forced trend, you should average over a reasonable time interval so as to smooth out – as much as possible – the impact of internal variability. That would mean using the 1979-1988 baseline in the figure (pink). I’ll leave you to guess what John Christy chose for his graph. I’ll also stop there and encourage you to read thoroughly Gavin’s post

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27 Responses to Models versus satellites

  1. Physics: “Ignoring all the potential issues with this graph, one problem is simply that it has never really been explained fully

    This sentence deserves some emphasis. In science a graph is useless if you do not know what is displayed, how it was computed.

    On the contrary, in the climate “debate” mitigation sceptics like to link directly to an image. Hashtag: just look at the data. This makes it impossible to see the text that describes how it was computed and, if it is a mitigation sceptical classic, it prevents reading comments of people explaining why it is misleading.

  2. Victor,

    In science a graph is useless if you do not know what is displayed, how it was computed.

    Exactly. Despite this, I think John Christy has argued that he doesn’t need to publish this graph in a peer-reviewed paper because all the data is from peer-reviewed sources.

  3. That Christy claim reminds me of:
    Just Kale Me: How your Kale habit is slowly destroying your health and the world
    http://huntgatherlove.com/content/just-kale-me-how-your-kale-habit-slowly-destroying-your-health-and-world

    Every claim is from peer-reviewed sources.

  4. Roger Pielke Sr did something similar when he suggested that we should ignore that Bob Tisdale’s ideas largely violate energy conservation and focus on his plots.

  5. Ethan Allen says:

    Gavin said …

    “Some more work is needed here to calculate the TMT trends with updated forcings (soon!), and that will help further clarify things.”

    I’d really like to see that one in the peer reviewed literature, as everything after 2005 is assumed forcings that appear to be too high. A blog article is OK, even better than non-peer reviewed congressional testimony (Curry’s are best as she depends on others to feed her data plots (e. g. UAH v6.0b4), so accepting on the appeal to authority of herself and of her on others, kind of ironic actually). But I doubt that even 666 peer reviewed papers on models versus observations will remotely stop those who will, from keep on keepin’ on.

    Either that or we all have to wait for the CMIP6 numbers (and the follow on nonsense of ‘you changed the models’)

    Expect a huge ‘response’ from the usual suspects.

  6. The Very Reverend Jebediah Hypotenuse says:

    In case folks haven’t see this, it is a classic.
    Show this to students on day 1.

    Used by the Florida Department of Law Enforcement, at first glance, it seems to suggest that the 2005 ‘Stand Your Ground’ law could be correlated with a reduction in gun-deaths…

    http://www.livescience.com/images/i/000/065/256/original/reuters-chart.jpg?1398285292

  7. JCH says:

    Lol, go NRA!

  8. Steven Mosher says:

    Code and data or I’m not reading any more blog science.

  9. The Very Reverend Jebediah Hypotenuse says:

    I want make, model, serial number, and current calibration certificates for all the sensors, plus e-mail and phone records from everyone.

  10. John Mashey says:

    ATTP + VV
    RE: useless graphs
    As you note, common, but this one if Christy’s is a JOHNny-come-lately among such.
    My favorite remains IPCC FAR Fig 7.1(c), Inhofe used in 2015, has appeared in dozens of books, and as best as i can tell, started with Lindzen in 1991, with video “Greening of planet Earth.”

  11. “I want make, model, serial number, and current calibration certificates for all the sensors, plus e-mail and phone records from everyone.”

    “This sentence deserves some emphasis. In science a graph is useless if you do not know what is displayed, how it was computed.”

    Nothing beats code to demonstrate how something was computed.

    WRT emails.

    Last I looked Christy presented that to Congress. Grijalva,anyone?
    someone call the AGs

  12. Dikran Marsupial says:

    “Code and data or I’m not reading any more blog science.”

    I don’t think code is necessary if the explanation of how the graph was generated is satisfactory. I’d rather have a good English description than R code, simply as I speak English much better than I speak R (I am more a MATLAB man), likewise there are those who don’t speak MATLAB etc, so there is no pleasing everybody. There is also the point that the code doesn’t necessarily do what the person who wrote it thinks it does, so the textual description is certainly not optional. A good textual description and code beats just code.

  13. I agree with Dikran. I’d rather have a description of how a figure/graph was produce than the code. Then I can try and do it myself using whatever code I’m familiar with. Taking some else’s code and running it to produce the same figure isn’t all that instructive if I don’t understand that particular coding language all that well.

  14. What jumps out at me when looking at Christy’s graphs relative to Schmidt’s is the quality of the work and the depth of knowledge he’s communicating. Maybe it’s just an aesthetics thing but when I look at Gavin’s work I see someone who is at the top of his game. He’s in full control and has full understanding of the materials he’s working with. Gavin also does a great job of presenting the actual challenges behind the research. John Christy’s work looks (to me) like an undergrad with an old pirated copy of Excel.

    To give him some credit, I know Christy is not a stupid person. But I do get the sense that the work he’s doing is sufficiently complex, in conjunction with his own personal ideological motivations, as to exceed his capabilities to advance the science on which he works.

  15. BBD says:

    That’s very charitable of you, Rob. In contrast, my cynical take is that Christy achieved exactly what he set out to achieve.

  16. angech says:

    Steven Mosher says:
    “I want make, model, serial number, and current calibration certificates for all the sensors, plus e-mail and phone records from everyone.”“This sentence deserves some emphasis. In science a graph is useless if you do not know what is displayed, how it was computed.”Nothing beats code to demonstrate how something was computed.”.
    All of the satellite data sets seem to run in unison, with similar dips and rises.
    Ask yourself if this a function of all using the same data sets or applying the same code rules with very minor tweaks depending on whether you are Mears or Christy.
    For what it is worth there seems to be a fair bit of unanimity with all the codes which means it should not be hard to replicate it? The Rosetta stone seems handy but I doubt you will get the code. Too Government sensitive?

  17. BBD… I would say, it’s very likely that Christy honestly believes what he is presenting is real and correct. But even within that assumption you’re essentially correct to say, “…Christy achieved exactly what he set out to achieve.”

    To me, Christy seems very bitter and angry over the entire climate issue. He’s clearly been labeled a misinformer when he thinks he’s trying to present scientific facts that present a conclusion different that overall climate research community. What I believe he’s incapable of seeing is how much his ideology colors what he presents. That, in a nutshell, is exactly what denial is.

    An interesting question might be, are there any climate contrarians who are substantially ideologically different from Christy/Spencer (Lindzen, Curry, Michaels, et al) who hold a similar position on climate change?

  18. Joseph says:

    An interesting question might be, are there any climate contrarians who are substantially ideologically different from Christy/Spencer (Lindzen, Curry, Michaels, et al) who hold a similar position on climate change?

    I copied the list of contrarian papers from populartechnology.com website and found that a relatively few authors contributed to a large number of the papers and that a significant number of the top contributors were associated with policy related think tanks. So I do believe there is a reason to think that there may be some ideological or political bias driving some “skeptics.”

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  20. BBD says:

    Rob Honeycutt

    BBD… I would say, it’s very likely that Christy honestly believes what he is presenting is real and correct. But even within that assumption you’re essentially correct to say, “…Christy achieved exactly what he set out to achieve.”

    To me, Christy seems very bitter and angry over the entire climate issue. He’s clearly been labeled a misinformer when he thinks he’s trying to present scientific facts that present a conclusion different that overall climate research community. What I believe he’s incapable of seeing is how much his ideology colors what he presents. That, in a nutshell, is exactly what denial is.

    I struggle with this when it comes to the few credentialed contrarians out there, so not just Christy. On the one hand I *want* to believe that they are honest but blinkered because I find it quite hard to accept that a scientist would lie about AGW. On the other, I find it very difficult to reconcile the scientific approach to evidence with the stuff the top-end contrarians come out with. Or put more directly: how the hell could they not see the glaring problems with their own work and presentations? I’m the proverbial bag of hammers compared to Gavin Schmidt but even I knew that graph was dodgy. Assuming Christy to be closer to GS on the spectrum of technical competence than he is to me, he *had* to have known that he was essentially misrepresenting data. To Congress, no less.

    I literally cannot get my head around it.

  21. snarkrates says:

    My Take on Christy, Lindzen and many other denialists is that they often know the arguments they are making at a given time are bogus, but they rationalize it by saying that they are adhering to a “higher truth”. They seem to be convinced that somehow a miracle will save us from the consequences of our own actions. In Lindzen’s case, I think the believes there is some magical negative feedback that keeps sensitivity low. Dyson believes that technology will save us, and all this worry about climate will have merely been a distraction. Christy and Woy? Maybe they think we are in the hands of their sky daddy.

    And Judy? I don’t think she cares as long as her denialist acolytes fawn and drool at her feet and the checks keep clearing.

  22. BBD says:

    snarkrates

    In Lindzen’s case, I think the believes there is some magical negative feedback that keeps sensitivity low.

    This is exactly what I mean. Lindzen knows his climate onions so he *must* know that palaeoclimate behaviour is almost impossible to explain if negative feedbacks are strong enough to maintain something close to homeostasis. Yet in the face of overwhelming contradictory evidence, he continues to argue his position. This isn’t science. But it could be pathological intellectual arrogance rather than calculated dishonesty. God only knows, but it is dangerous and indefensible.

  23. Magma says:

    An interesting question might be, are there any climate contrarians who are substantially ideologically different from Christy/Spencer (Lindzen, Curry, Michaels, et al) who hold a similar position on climate change? — Rob Honeycutt

    Yes, that is an interesting question. You could also add Roger Pielke Sr. to the list, and outside of climate scientists sensu stricto (but still well in the realm of climate contrarians) Steve McIntyre and Ross McKitrick, Ian Plimer, (the late) Bob Carter, Don Easterbrook, and a few others. As far as I’ve been able to tell their ideological stances are generally quite close. You could almost sum up their collective scientific argument as “anthropogenic climate change has been disproved because… socialism!

    I can’t think of any left-leaning or politically centrist contrarians, although human nature being what it is those listed above would probably all consider themselves to be centrists and models of moderation and open-mindedness.

  24. And… There are definitely ideologically right-leaning people out there who support the consensus position. Like, Kerry Emanuel, Jim Hansen, Richard Alley…

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  26. Magma says:

    @ Rob Honeycutt: compared to many of the ‘skeptics’ I see posting on mainstream media sites or denier blogs, those three (and fellow Republican Barry Bickmore at BYU) are flaming Trotskyites.

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