A few things

I haven’t really had anything particular to say for the last day or so, so thought I would just write a post with a few thoughts. Having given the moderation issue some more thought, the main change I will be making is to insist on evidence if you want to introduce what might be a contentious topic. I don’t want to constrain the comment threads too much, but also don’t want them going of on random trajectories that are unlikely to be constructive. Hence, if you would like to make introduce such a topic into the discussion, you’re going to have to provide some pretty convincing evidence. As I mention in my updated Moderation page, some emails between a few individuals is not going to qualify as evidence that all of climate science is fundamentally dishonest. Also, Rachel has, very kindly, offered to help and so we may see some slightly more effective moderation in the future.

In other news, I noticed that Doug Keenan is back at Watts Up With That (WUWT) with another post about the statistical analysis of surface temperatures. He continues to argue that

All such statistical analyses of the temperatures that have been done so far are fatally flawed…..

The flaws imply that there is no demonstrated observational evidence that global temperatures have significantly increased (i.e. increased more than would be expected from natural climatic variation alone).

This is, I believe, based on a parliamentary question, followed by a response from the UK Met Office. He seems to be arguing that statistical models cannot explain why the surface temperatures have varied as they have (which is kind of obvious) and therefore we can assume that they might not have varied as they have. I’ve covered this in an earlier post and Richard Telford has a very good post pointing out that statistics are not a substitute for physics (I really wish more would recognise this rather obvious point).

One other thing I was going to comment on was a recent post on The Hockey Schtick. The post is called a new paper demonstrates climates models don’t even have ‘basic physics’ of the greenhouse effect right. It refers to a paper by Russell et al. (2013) called Fast Atmosphere–ocean Model Runs with Large Changes in CO2. The paper’s abstract ends with

With CO2 at or below 1/8 of the 1950 value, runaway sea ice does occur as the planet cascades to a snowball Earth climate with fully ice covered oceans and global mean surface temperatures near –30oC.

The Hockey Schtick post comments that

However, -30oC is much colder than the -18oC calculated for an Earth with no atmosphere or oceans or greenhouse effect at all! Further, -30oC is much, much colder [i.e. 35oC colder] than the +5°C global mean temperature calculated using the IPCC formula for CO2 forcing using a CO2 level of 39 ppm.

To be honest, I was slightly confused about this myself until I realised: it’s a snowball earth so, presumably, the albedo would higher than it is today. It’s fairly straightforward to estimate the non-greenhouse temperature of a planet. The basic equations are
PlanetTemp
Most of the terms are fairly self-explanatory (if you’re uncertain about these equations and terms, feel free to ask and I’ll explain further), but A is the albedo, and a is the distance of the planet from the Sun. Currently A is about 0.3. If you solve for Tpl in the above equation using A = 0.3, you do indeed get Tpl = 255 K = -18oC. However, if the Earth has fully ice-covered oceans A would be considerably greater than 0.3. Using A = 0.5 gives Tpl = 235 K = -37oC. So, it’s not that surprising that the models with CO2 concentrations of 39 ppm had surface temperatures of about -30oC. One of the reasons I was wanting to write about this is that one of the paper’s authors, Chris Colose, posted a comment at the Hockey Schtick to point out that

You didn’t read our paper. The albedo in a Snowball is much higher than present-day, so temps can go go well below the modern effective temperature of 255 K. This is an elementary point.

So, does the author of the Hockey Schtick post quickly respond with what might be regarded as the obvious response : “Of course, how silly of me. I should have realised that. Thank you for commenting”? To find out, you could either read the HS comments, or you could simply take an educated guess. In this case, if you were to select what might – to many – be the obvious answer, you’d most likely be correct.

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33 Responses to A few things

  1. Rachel says:

    Wotts says: “…so we may see some slightly more effective moderation in the future.”
    It may be a case of the blind leading the blind here Wotts. 😉 But I will do my best.

    I saw a tweet from Chris Colose about his paper and the Hockey Schtick post. Extraordinary. No-one seems to have read or taken any notice whatsoever of his comment either.

  2. I missed his tweet. It’s certainly seems to be another example where a little knowledge can be a dangerous thing.

  3. Rachel says:

    It’s also one of those things that’s easily explained and easy to understand. A bit like Salby’s problem of negative CO2. Chris explains it in one sentence.

  4. BBD says:

    And of course, CO2 forcing is the major mechanism that breaks the climate system out of its albedo-locked icehouse.

    Otherwise, we would still be in it.

  5. The best end to a comment that I’ve seen is Jeremy Kemp’s response on Making Science Public to a comment by Maurizio Morabito (who’s online persona is – I think – Omnologos). The comment ends with

    It’s difficult to express just how basic a concept that is.

  6. Yes, and it’s one of the other examples of where CO2 was the driver of climate change.

  7. > To find out, you could either read the HS comments, or you could simply take an educated guess.

    You made me look, Wotts.

  8. Apologies. That’s why I presented what I thought was a reasonable alternative 🙂

  9. Rachel says:

    That’s how I felt. It’s so hard to resist looking even though you know you don’t want to.

  10. BBD says:

    Sorry. No evidence 🙂

    You’d need a heck of a lot of CO2 forcing to do this, but Abbot & Pierrehumbert (2010) hypothesises that an increasingly grubby ice around the equator may have reduced albedo and so the amount of RF necessary to trigger deglaciation. But the debate is over how much CO2 is required, not if it is required.

  11. BBD says:

    That reads badly. As usual, we crossed 😉

    I was referring to my own unsupported previous assertion. Didn’t want to be the first to end up in moderation for arm-waving…

  12. BBD says:

    The fascination of the…

    😉

  13. Rachel says:

    It’s like telling a child not to touch something.

  14. Richard Telford has a post on Keenan’s op-ed:

    http://quantpalaeo.wordpress.com/2013/10/31/statistics-are-not-a-substitute-for-physics/

    Doug should write a non linear cuisine cookbook.

  15. Did you actually read my post 🙂

  16. I mean: a non-stationary cuisine cookbook.

    Halloween time.

  17. BBD says:

    We’re getting that here. Could it be going global?

    “I can feel it, Dave…”

    😉

  18. You did not make me look, Wotts.

    I liked Richard’s kicker:

    > Replacing an oversimplified but informative model with a physically meaningless model is not progress.

    I find it apropos considering the model bashing that takes place at Judy’s right now.

  19. KR says:

    Keenan’s post is just another “random walk” assertion – completely unsupportable in the presence of thermodynamics.

  20. Yes, that does rather sum it up very well. Isn’t Judy giving a talk today about models? If so, I wonder how that will go.

  21. Brad Keyes says:

    “As I mention in my updated Moderation page, some emails between a few individuals is not going to qualify as evidence that all of climate science is fundamentally dishonest.”

    Fair enough. But who attempted such a generalisation, and what was their reasoning? I’ve never heard anyone suggest, for example, that the rest of the climate-science profession is nearly as bad as the people who actually wrote the emails (Mann, Jones and their tight-knit address book).

  22. Rachel says:

    Brad,
    Wotts does not want a discussion here about the climategate emails especially when the claims made are unsubstantiated. Consider this your first warning. I will edit any future comments made like this. Please drop the topic.

    I am about to get on a plane now though so please please respect the rules of our host here.

  23. There we go. I arrive at the work to find the new moderation technique working seamlessly 🙂

  24. Brad Keyes says:

    That’s absolutely fine by me, Rachel. It’s Wotts’ blog and if she doesn’t want anyone talking about them, I’m more than happy not to.

    Perhaps, though, she should just come out and say it:

    “No discussing the Climategate emails, please.”

    It’s a simple rule, simply stated, which ought to be simply visible on the Moderation page, in my simple-minded way of looking at things :-p

    Anyway, enjoy your flight!

    Well, “enjoy” is perhaps the wrong word, since I’m sure you wouldn’t fly frivolously. 😉

  25. wotts, you say

    ” I’ve covered this in an earlier post…”

    In that earlier post, you say: (emphasis in original)

    “Without having to do any kind of statistical analysis it’s fairly clear that temperatures today are about 0.8C higher than they were 130 years ago”

    This is in rebuttal to Keenan, whose contention is:

    “The above again illustrates that, when determining whether an increase/decrease in a time series is significant, we cannot just look at a plot of the data. We must use statistical analysis.”

    Clearly, this shows that you have not ‘covered’ anything. All you’ve done is simply state the opposite of what you are (supposedly) trying to rebut.

    I don’t know about you, but in my work, that is not considered a rebuttal, a reply, a ‘covering’ or any such thing.

    Secondly, you state:

    “He[Keenan] seems to be arguing that statistical models cannot explain why the surface temperatures have varied as they have …”

    Really? Is that your summary of Keenan’s point? To me, this shows that you lack understanding in this crucial area of statistical inference.

    A statistical model will not explain why temperatures vary. It will explain whether they have varied.

    The key question is: Are temperatures higher than what can be expected with natural variability?To answer this, we need data that adequately encompasses natural variability. As a rule of thumb, it can be said that data that seeks to examine change over and above variability at a given time scale should include enough instances of such variation.

    The above is easily illustrated: if you want to measure body temperature to determine ‘fever’, you cannot measure normally occurring diurnal variation from a low to a high, conclude that temperatures are ‘rising’ and declare a fever. It has to be higher than the possible high. That is possible only when there is enough knowledge on how high it can actually go, i.e., measurements conducted over several days.

  26. Will he get a second warning?

  27. Brad Keyes says:

    Shub,

    I’m not sure it’s exactly possible to consider Rachel’s comment a “warning” in the first place. More like a “polite explanation of a new rule not mentioned anywhere on the Moderation Policy page.” Again, this may be my simple-mindedness speaking, but without time-travel technology it does seem a bit of stretch to “warn” someone for violation of a rule while introducing that rule.

  28. “Wotts does not want a discussion here about the climategate emails especially when the claims made are unsubstantiated. ”

    Rachel, this is terrible. Is Brad discussing the Climategate emails? No.

    The question is, who, in this blog, used Climategate emails to imply that all climate science is corrupt? ‘Some are corrupt’, and ‘there is corruption’ is different from saying ‘all of climate science is corrupt’.

    You are asking that a topic be dropped, based on a wrong interpretation what the point in discussion is.

  29. Okay, let’s make something clear. I did not say anyone had done so. I was giving an example of what I regard as insufficient evidence. That was all. Let’s not turn this into a major discussion about whether or not someone has actually used this as an example. No they haven’t (or I can’t remember anyone having so) and I didn’t say anyone had.

    Rachel’s moderation was perfectly reasonable.

  30. Shub, it was a perfectly reasonable rebuttal. A statistical analysis (like linear regression) simply tells you what the trend is and can be used to determine the errors/uncertainties. It does not tell you anything about why the trend is what it is. For that you need some kind of physically motivated model. My simple point was that – quite obviously – the global surface temperatures today are higher than they were in 1880. I was making no claim as to whether it was higher because of some natural variation or because of anthropic influences. A statistical analysis cannot answer that question. It is simply obvious that it is higher. I don’t need to do a statistical analysis to see that. Doug Keenan explicitly stated that a zero trend was a possibility. He is wrong.

    You say

    A statistical model will not explain why temperatures vary. It will explain whether they have varied.

    which is entirely consistent with what I was saying. Doug Keenan is clearly claiming that there might have been no warming – as far as I’m concerned, over the time period 1880 – 2013 this is incorrect.

  31. > A statistical model will not explain why temperatures vary. It will explain whether they have varied.

    In what way does a statistical model explain anything?

  32. BBD says:

    Echoes of your defence of Salby, Shub.

    Two demonstrations now that you do not understand that which you promote.

    That is very, very unsceptical indeed.

  33. BBD says:

    The key question is: Are temperatures higher than what can be expected with natural variability?

    Yes. See eg. Huber & Knutti (2011). This is a dead issue, as you should know since you style yourself something of an expert in matters of climate science.

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