Climate Model Predictions and What Happened

In a comment on a previous post about lack of convincing evidence for climate models — the ones that predict catastrophe — I wrote:

At any time — right now, 5 years ago, 10 years, 15 years ago –” the people who work with those models and claim we should pay attention to their predictions could make/have made a set of predictions: next year, the year after that, and so on. Then, as time passed, we would have found out if the models predict correctly. The modelers haven’t done that.

From this talk by Richard Muller, a Berkeley physicist, I learned of two instances where the modelers did what I said they haven’t done.

1. In 2009, James Hansen predicted, based on his model, that 2010 would be the hottest year on record. Since temperatures had been roughly constant — not rising — for the previous 12 years, this was an interesting prediction. When 2010 ended, Hansen’s own data (analyzed in an unusual way, according to Muller) found this to be true, but two other datasets found it to be false.

2. In 2001, several scientists, based on nine climate models, predicted that Antarctic ice would increase over the next ten years. In fact, it decreased (“exactly the opposite of the prediction”). In response, John Holdren, President Obama’s science advisor, said, according to Muller (at 26:22):

Well, those models were really wrong. But now we’ve changed those models. And now if we run them again they show that the ice will decrease. And therefore this is evidence in favor of global warming.

The audience tittered.

If you think Climategate was not important, and that the scientists whose email was revealed did nothing seriously wrong — as several official investigations, Bill McKibben (“if you managed to hack 3,000 emails from some scientist’s account, you might well find a few that showed them behaving badly”) and New Yorker staff writer Elizabeth Kolbert have concluded — you should see what Muller says about it (starting about 30:00).

I liked the talk. Muller makes several points with which I agree and presents helpful data. However, there were several things I didn’t like. There is one big gap. Muller thinks current climate models are probably right, but doesn’t explain why. I would have liked to know. And he says two things with which I deeply disagree. First, he says scientists shouldn’t say what the data will show — that is, make predictions. I believe that making and testing predictions is by far the best way to learn how much we know. Second, Muller says that buying a Prius does nothing. The improvement is too small, the cost of a Prius too great. People in China can’t afford a Prius, says Muller. This misses a really important point. When you buy a Prius you are supporting innovation. To solve the big problems that arise in any society, innovators need support. My theory of human evolution goes on and on about this. Long ago, connoisseurs supported innovation. Festivals such as Christmas supported innovation. Art lovers supported innovation. Fashion supported innovation. The great achievement of Tyler Cowen’s new book The Great Stagnation, which I will discuss tomorrow, is its focus on rate of innovation. What controls rate of innovation is a supremely important question usually ignored by economists — as Muller ignores it.

In any case, here are two actual predictions and how they fared.

28 Replies to “Climate Model Predictions and What Happened”

  1. OED:

    “4. intr. To laugh in a suppressed way, titter, giggle.”

    ” b. transf. [. . .] also (esp. of a woman), to talk or chatter rapidly in a small or tremulous voice.”

    Or perhaps a portmanteau word: to tweet a titter.

  2. I recommend Muller’s book “Physics for Future Presidents”. His chapter in climate change is very reasonable, as are his chapters on other controversial topics. The man seemed very honest and perfectly willing to slay a few sacred cows. It’s also a good read. I learned a lot.

  3. “temperatures had been roughly constant — not rising — for the previous 12 years”

    What is this claim based on? If you take the annual global temperatures from 1998-2009 and plot a best-fit line through them, it has a slope of +.12C per decade. That’s only slightly less than +.16C per decade that you get if you fit a line to the 1970-1998 data. And you picked the endpoint of 1998, which was unusually hot and well above the trend line.

  4. There is another instance where it was done; Jim Hansen presented the predictions of his climate model in his congressional testimony in 1988.

    His forecast did pretty well for the first 15 years or so, then it started getting off track. See here:

    When I argue models with warmists, the usual defense is to assert that climate is easier to predict over a 20 or 30 year time frame than it is over a 2 or 3 year time frame. But there really is no evidence or reason to believe this is so.

    Also, the UK met office has been making year-by-year predictions for 10 years or so now. However, any layman can see that this model fails the persistence test. i.e. if you just take each year’s temperature and use it as the prediction for the next year, you would have gotten a more accurate prediction than that of the met office model.

    What’s interesting is that the warmist community does not seem to understand or accept that the UK met office model has failed this most basic statistical test of validity.

  5. Vince, my claim of constant temperatures is based on what Muller said. I am just repeating what he said.

    sabril, in James Hansen’s 1988 predictions there was no comparison to a simple linear extrapolation. Perhaps temperature was already rising at the predicted rate of increase. If so, it was no great success for the model to correctly predict a continuation of that trend. The model should be able to do better than a high school student. The accurate prediction of the first 15 years means nothing until it is clear that the model did better than common sense. Your UK met office example is the same point.

  6. There’s a Scott Adams cartoon that runs as follows.
    (Enter Dilbert, clutching a box): I got it! I’m the first person in city to own a videophone!
    (Opening box by the TV): Now all I have to do is set it up and wait for someone to call me.
    (Videophone is set up on top of TV, all TV displays is static)
    (TV still displays static, Dilbert sits there vacantly) Dogbert: The funny thing is, we need people like you to move technology along.

  7. The “climategate” e-mails didn’t reveal anything more than pique toward petroleum industry shills. I don’t need to hear what Muller says; I read all the “incriminating” e-mails myself, and their context. There is really nothing there. Echoing Seth’s comment last week, those were the best they could come up with, and they weren’t anything. I don’t need to dig deeper and read all the “less incriminating” e-mails — they’re even less than not-anything. The whole fake controversy was ginned up by those same shills. The shills are just doing the job they’re paid for; what’s shameful is in being taken in. (Likewise, the Koch brothers and their teabaggers, respectively.)

    Seth, people are always pointing you to compelling predictions and proofs. You’re having to work harder and harder not to see them, and to make any tiny hint of ambiguity you can eke out into a smoking gun. People who have sent tens of thousands of dollars to Nigerian 419 scams maintain, on their way to prison, that the millions really bare there waiting for them, and they’d have got them already if not for corruption at all levels of government. Psychology must have a name for that.

  8. I think there are three parts of the Global Warming argument to contend with.

    1) Are there more greenhouse gases in the atmosphere than in centuries past? I’m not an expert in the field, but the experts seem to be saying that’s true and I haven’t seen any disagreement on that point to speak of. Maybe there is some controversy on this point, but I haven’t seen it.

    2) Assuming you except #1, we can ask: are human behaviors contributing to the increase in greenhouse gases? Again, the link between our collective carbon footprint and the evidence of more greenhouse gases seems to be fairly well-accepted.

    Ok, if you sign on to those two points, I think you basically have to acknowledge that humans are changing the world in a way that could be dangerous. In other words, we’re polluting Earth to the detriment of future generations.

    It would be nice to believe that the climate models (argument #3 in the Global Warming debate) are going to be accurate so that we could quantify how much in resources we should spend to reduce our carbon footprint. But, like Seth, I’m skeptical of their accuracy. I’ve spent a fair amount of time watching the models of how we might expect baseball players to perform from one year to the next and that took some time to get right– and it seems much, much easier to predict baseball players’ correctly than to shape an accurate climate model. So, I’m skeptical about these models’ accuracy.

    Here’s the thing, though. If you’re skeptical about their accuracy and you basically accept #1 and #2, I think you pretty much have to admit that the climate models could be underestimating the change. That is, our best scientists, for all we know, could be wildly underpredicting the impact of our carbon footprint.

    It makes sense to me to use the best science we have to estimate the resources we should spend to correct this situation before future generations suffer from our polluting ways.

  9. This debate is interesting in that the climate change side is firmly convinced that anthropogenic warming is a threat, the denialists side is adamant it’s not, and both sides accuse the other of bias. Very few people rest in the middle, which makes this issue almost a matter of politics rather than science, much like Republicans vs Liberals. If you’re an environmentalist you’re probably going to be on the anthropogenic warming side, and if you’re a free market advocate, probably a denier. Has anybody else noticed this?

  10. “The ‘climategate’ e-mails didn’t reveal anything more than pique toward petroleum industry shills.”

    Well would you agree that at a minimum, the e-mails show that

    (1) one or more of the researchers in question are advocates for a certain point of view? i.e. they wish to put the best possible spin on things in order to persuade the public that their position is correct;

    (2) one or more of the researchers attempted to prevent the publication of articles which disagreed with their position;

    (3) one or more of the researchers attempted to game the system to prevent their perceived adversaries from obtaining documents through freedom of information requests.

  11. “Seth, people are always pointing you to compelling predictions and proofs. ”

    I realize that this comment is not addressed to me, but I really would like to see an example where these climate simulations were tested by successfully making bona fide interesting predictions.

    Let’s do it this way: In your view, what is the most compelling example of climate simulations making accurate, bona fide, interesting predictions?

  12. I like Withrow’s point, at least it describes how I come to this issue. We have a strong reason to believe points 1 & 2, so what do we do now? I agree that models are likely imperfect, and that future testing would be ideal, but we have to decide whether to cross the Rubicon now. And not to choose is to choose. (Sorry, it seems like a stream of cliches, but I hope it gets across my point.) In other words, we can’t wait for perfection, we can’t wait 20, 50, or 100 years to check out “who was right”. Indeed, scientifically, isn’t looking into the future much like looking into the past to judge, for instance, evolution? We can’t test evolution by its predictive power, we can’t replicate it in a lab, but we believe it. (I do.) Isn’t the theory of evolution explanatory but not predictive?

  13. The really damning thing about Climategate was not the emails, but the code that was released. The comments are amazing. Most people have only seen the emails, which are easy to dismiss- the code not so much.

  14. Tierney, Muller’s talk makes clear what a big difference it makes to “hide the decline”, also known as “Mike’s trick”. I had not seen that pointed out before. When you “hide the decline” (which is shorthand for several changes) the graph that you get (which is what was published) becomes far more favorable to the case that Mann and his colleagues were pushing. And this is entirely separate from the weird data analysis that produced the Hockey Stick. The emails are easy to dismiss, I agree — until you know what “hide the decline” actually means.,

  15. Sean: Your observation is painfully obvious, but backwards: The sole reason for the “controversy” over global warming is that the honestly expressed implications of the research results demand public policy changes that would (“inconveniently”) interrupt extraction of rent on long-held properties.

    Sabril: Seth has expressed, again and again, that he’s really not interested in looking at evidence. The dance is a two-step. The first step is that the only evidence worth looking at is global temperature predicted after the present. The second step is that the only prediction to take seriously is one that does not forecast a temperature rise. The first means that there will never be a time to examine results of predictions. The second means that having predicted correctly automatically disqualifies a model as trivial.

    In response to your three points:

    (1) All researchers are advocates of a point of view. Some lie and say they aren’t. If they express a foolish point of view, legions of other researchers are eager to jump down their throats. When many scientists expose their point of view, it means no serious criticism remains to be demolished.

    (2) Nobody can prevent publication. The shills in question were handicapped mainly by never having done any research of their own.

    (3) All productive researchers use every imaginable trick (oops! there’s that word) to keep [censored] from wasting their time. For each minute of each day, a whole crowd of [censored] lies in wait to make off with it. Scientists not harassed by {censored] are often doing nothing interesting. (Scott Adams’s first book was about this, titled, “Always Postpone Meetings with Time-wasting Morons”.)

    Steve G: Natural selection has recently been made predictive, and has been replicated in labs all over the world. As pointed out earlier, “prediction” needn’t refer to linear time. Paleontologists routinely make predictions about what a complete specimen (that died millions of years before their birth) will be found to reveal, and are roundly ridiculed when they predict wrong — just as in other disciplines.

  16. I read the e-mails. I also read the code, and the comments in the code. The “hide the decline” and “Mike’s trick” comments have been examined thoroughly by several independent commissions, and have been found to have absolutely innocuous implications. Everyone who cares has seen detailed demonstrations of this.

    Paraphrasing Seth, again, when the very smokingest gun they can come up with turns out to be a trick cigarette lighter, there’s no point in looking further. This is not only because other offerings will be even weaker. It is also because it reveals that they are trying to deceive you, so all further efforts will be to that end.

  17. ” All researchers are advocates of a point of view”

    I basically agree, which is why it is troubling when people like Gavin Schmidt pretend that they are not advocates.

    “Nobody can prevent publication.”

    Does this mean yes or no? Are claiming that none of the researchers in question attempted to prevent publication of any article?

    “All productive researchers use every imaginable trick (oops! there’s that word) to keep [censored] from wasting their time.”

    So it sounds like you are saying that (1) yes, one or more of the researchers in question attempted to game the system to prevent their perceived adversaries from getting information through freedom of information requests; (2) they did it primarily to save time and not to prevent scrutiny of their work; and (3) all researchers engage in this sort of behavior.

    Do I understand you correctly?

    Oh, and in your view, what is the most compelling example of climate simulations making accurate, bona fide, interesting predictions?

  18. Nathan, according to you “the only prediction [I, Seth] take seriously is one that does not forecast a temperature rise.” See Prediction #1 in this post for a counter example.

  19. (1) There are honest and dishonest ways to advocate a point of view. The former is what Gavin Schmidt is doing. Promoting transparently phony “climategate” scandals is the latter. Being seen to engage in the latter reveals true intentions.

    (2) It doesn’t matter who, if anybody, tried to prevent publication. My opinion about what they meant to do matters even less. If they had tried to prevent publication of real work, they would fail. If the shills did real work, they wouldn’t be shills. Much of the apparatus of science is geared to preventing publication of substandard and deliberately misleading works (although it often fails), and it’s part of every scientist’s job to help.

    (3) They did not “attempt to game the system”; they discussed possible actions that they decided against. All productive researchers are obliged to engage in variations of “this sort of behavior”, if by that you mean putting off time-wasting [censored] whenever and as long as possible. I applaud all such efforts, because I want scientists to do science. I understand that not everybody wants that.

    (4) You can’t fool me, it’s turtles all the way down.

  20. “There are honest and dishonest ways to advocate a point of view. The former is what Gavin Schmidt is doing”

    That’s simply not true. Here’s an (apparent) quote from him:


    “Climate scientists are paid to do climate science,” said Gavin A. Schmidt, a senior climatologist with the National Aeronautics and Space Administration’s Goddard Institute of Space Studies. “Their job is not persuading the public.”


    A reasonable person reading this would understand that Gavin Schmidt is attempting to pass himself off as being disinterested; neutral; NOT an advocate with a position.

    “It doesn’t matter who, if anybody, tried to prevent publication.”

    Why are you evading my question? It’s not a trick question. It doesn’t have any hidden assumptions in it. Yes or no, please.

    “They did not ‘attempt to game the system’; they discussed possible actions that they decided against.”

    Again, this is simply not true. Here is one of the Climategate e-mails:

    “I had some emails with him [McIntyre] a few years ago when he wanted to get all the station temperature data we use here in Climatic Research Unit. At that time, I hid behind the fact that some of the data had been received from individuals and not directly from Met(eorological) Services through the Global Tele-communications Service (GTS) or through the Global Climate Observing System”

    Clearly the e-mail author (Phil Jones) was attempting to invent excuses to avoid disclosing information to a perceived adversary.

    “All productive researchers are obliged to engage in variations of ‘this sort of behavior'”

    Researchers are obliged to invent excuses to avoid complying with freedom of information requests?

    Anyway, it’s not a waste of time for a researcher to turn his data over to a hostile adversary. The adversary might find something wrong with the researcher’s data, methods, or results. This is a valuable and productive result.

    Besides, if it was really about saving time, the climategate folks would not have objected to the release of the climategate e-mails. Instead, they would have said something like this:

    “We want to thank whoever leaked this information. We really wanted to do it ourselves, but we did not have the 3 or 4 minutes required to burn all the e-mails to a DVD and drop them in the mail. Thank you for saving us 3 or 4 minutes!!”

    And again:

    In your view, what is the most compelling example of climate simulations making accurate, bona fide, interesting predictions?

  21. And by the way, if there were any doubt that a significant part of Jones’ motivation was simply to shield his work from scrutiny, he kinda spilled the beans with this little gem:

    “Why should I make the data available to you, when your aim is to try and find something wrong with it”

  22. Climate scientists really are paid to do climate science. They are also citizens who have a civic responsibility to speak out about public policy that is at odds with
    reality. There is no contradiction, but they do make conflicting demands on one’s time — along with family and other needs. Each of us is obliged to sort out those demands as well as we can.

    Most of your questions are already answered in my previous posting, typically in the very next sentence or clause after the bit you quoted. Do please read.

    The response to the e-mail release has been profoundly distracting. No one who wanted to actually do, you know, climate science, welcomes such distractions.

  23. “There is no contradiction”

    The question is not whether it’s a contradiction. The question is whether it is dishonest for people like Gavin Schmidt to pretend that they are not advocates when in reality they are.

    If these warmist researchers came right out and admitted that they are advocates; that they will do their best to put the best possible spin on things in order to support their position; that they will attempt to prevent dissenters from having their work published; that they feel justified in inventing excuses to dodge freedom of information requests in order to shield their work from scrutiny; etc.; then I would have much less of a problem with them. (Of course, I would oppose public funding for such individuals.)

    “Most of your questions are already answered in my previous posting”

    Nonsense, and the fact that you are unable to concede points which are clear to any reasonable person underscores the whole problem with the warmist side of the debate.

    These are people who (apparently) feel perfectly justified in attempting to silence dissent; withholding data; and in general spinning things to put their pre-determined view of reality in the best possible light. Meanwhile, they have not offered hard objective evidence that their climate simulations are correct, such as bona fide, interesting, accurate predictions. Instead, we are simply supposed to trust them. But their behavior shows that they cannot be trusted.

  24. withrow and Steve G., it is a fair question, but it’s saddening that you aren’t even aware of the counter-arguments. A good read would be

    The root of the issue is the magnitudes involved. If the effect of more CO2 is small, then there’s no reason to worry. If the effect of emissions control is weak, then it’s a pointless strategy to attempt, and we should look for a better answer.

    The expected effect of more CO2 is where there has been especially shoddy science being published. Occam’s Razor suggests that the effect will be small, because the effect is due to the greenhouse effect of CO2 in the atmosphere. We are already past 50% of the maximum possible greenhouse effect due to CO2, so why would we expect having any more than that effect once more, no matter how much CO2 we put out? There are efforts to argue that we approach some sort of tipping point that would cause the a larger effect from later amounts of CO2 than earlier amounts. There’s not much evidence for any such effect that is also consistent with the Earth’s history as we know it. In particular, we’ve had high CO2 in the past without seeing any sort of tipping point, so why should it be different in the modern era?

    The expected effect of emissions control, meanwhile, is small. To really stop CO2 levels from growing, cutting emissions by half is not enough. The cuts have to be more like 80-90% world-wide. Such cuts would have severe negative impact on human quality of life, so no such proposals are being floated. However, if the cuts are anything less — or if, like Kyoto, they don’t even reduce emissions at all — then CO2 levels will keep rising. In that case, the emissions control just delays our doom instead of preventing it, and we still need an alternate solution eventually.

  25. “A good read would be”

    I agree 100%.

    “The root of the issue is the magnitudes involved”

    I agree with this too. It’s amazing how many people there are who think they understand the science but who don’t know that the critical issue is water vapor feedback.

    “The expected effect of emissions control, meanwhile, is small.”

    I agree with this too, and I would add that the proposals on the table are probably even less effective than they seem, since they are likely to result in some amounts of CO2 emissions simply being shifted from places like the US to places like China.

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