Some of you might wonder why I make so many posts about the impact of noise on trend analysis, and how it can not only lead to mistaken conclusions about temperature trends, it can be abused by those who wish deliberately to mislead readers. The reason is that this is still a common tactic by denialists to confuse and confound the public.
Case in point: Bjorn Lomborg has written an article for the British newspaper The Guardian in which he attempts to persuade readers that climate data indicate conditions are much better than expected. Here’s a excerpt:
The most obvious point about global warming is that the planet is heating up. It has warmed about 1C (1.8F) over the past century, and is predicted by the United Nations’ climate panel (IPCC) to warm between 1.6-3.8C (2.9-6.8F) during this century, mainly owing to increased CO2. An average of all 38 available standard runs from the IPCC shows that models expect a temperature increase in this decade of about 0.2C.But this is not at all what we have seen. And this is true for all surface temperature measures, and even more so for both satellite measures. Temperatures in this decade have not been worse than expected; in fact, they have not even been increasing. They have actually decreased by between 0.01 and 0.1C per decade. On the most important indicator of global warming, temperature development, we ought to hear that the data are actually much better than expected.
Lomborg doesn’t say exactly what he means by “this decade,” nor does he state exactly what data set(s) lead him to his conclusions. But it’s a pretty safe bet that by “both satellite measures” he refers to the RSS and UAH estimates of TLT (lower-troposphere temperature). The most natural meaning of “this decade” is — well, this decade, i.e., the 2000’s. So I computed the trend and its uncertainty (in deg.C/decade) for three data sets: NASA GISS, RSS TLT, and UAH TLT, using data from 2000 to the present. To estimate the uncertainties, I modelled the noise as an ARMA(1,1) process. Here are the results:
| Data | Rate (deg.C/decade) |
Uncertainty (2-sigma) |
| GISS | +0.11 | 0.28 |
| RSS | +0.03 | 0.40 |
| UAH | +0.05 | 0.42 |
All three of these show warming during “this decade,” although for none of them is the result statistically significant.
Maybe by “this decade” he’s referring to the last 10 years. Let’s make the same calculation for the same data sets, using the last 10 years of data, from October 1998 through September 2008:
| Data | Rate (deg.C/decade) |
Uncertainty (2-sigma) |
| GISS | +0.18 | 0.23 |
| RSS | +0.10 | 0.34 |
| UAH | +0.11 | 0.35 |
Once again all three data sets indicate warming but none of the results is statistically significant.
Maybe, by “this decade,” he’s referring to data since 1998? But that would be the worst cherry-picking possible, extending “this decade” to more than 10 years ago just so he could get the most out of the giant el Nino of 1998. We all know that would be cheating, right? Let’s make the same calculation using data from January 1998 to the present:
| Data | Rate (deg.C/decade) |
Uncertainty (2-sigma) |
| GISS | +0.10 | 0.22 |
| RSS | -0.07 | 0.38 |
| UAH | -0.05 | 0.38 |
Finally one can obtain negative trend rates, but only for 2 of the 3 data sets. But again, none of the results is statistically significant. Even allowing this dreadfully dishonest cherry-picked start date, the most favorable case for Lomborg’s claim indicates that the trend rate could be as high as +0.31 deg.C/decade. That’s right, based on these data the trend rate could well be 50% higher than the IPCC “projection” of “about” 0.2 deg.C/decade.
How, then, does Lomborg arrive at his figures? Only God and Bjorn can be sure. But here’s my guess: he took the results from 1998, computed the uncertainty based on assuming that the data are a linear trend plus white noise (which we know, without doubt, is a terribly mistaken assumption), then computed his “range” by using only +/- one sigma. That would, in fact, give a range from -0.01 to -0.1 deg.C/decade.
What do you have to do to make this happen?
One of these might be considered an honest mistake. If you’re woefully ignorant of statistics, you may not know that the noise in global temperature isn’t white.
But the others are outright dishonest. Computing a confidence interval using only 1 sigma is bound to be wrong nearly one third of the time. And starting with the beginning of 1998, referring to “this decade” as starting more than 10 years ago, is cherry-picking taken to the extreme.
I’ve previously said “Those who point to 10-year “trends,” or 7-year “trends,” to claim that global warming has come to a halt, or even slowed, are fooling themselves.” I may have been mistaken; is Lomborg fooling himself, or does he know exactly what he’s doing?
So, Mr. Lomborg, we’re all very curious: how did you get those numbers?
62 responses so far ↓
Mark Hadfield // October 14, 2008 at 11:17 pm
But surely he wouldn’t have made such a claim without citing a peer-reviewed paper in which the methods and results are described in detail?
David B. Benson // October 14, 2008 at 11:22 pm
Tamino — I am sure that God is confused and questioning as well…
Brian D // October 15, 2008 at 12:49 am
Mark Hadfield: You’d imagine so, but there aren’t any citations. There’s quotes from the Associated Press and the BBC, but that’s it.
Tamino, have you considered sending this to the Guardian as a rebuttal (perhaps through an intermediary, if you’d prefer to remain anonymous as usual)? Lomborg, if he is fooling himself, isn’t going to be convinced by mere facts, but at least points like this can prevent others from being fooled themselves.
Ray Ladbury // October 15, 2008 at 1:13 am
I’m SHOCKED!!! SHOCKED!!! to find Lomborg playing fast and loose with statistics. (where are my winnings)
[Response: I think this is the beginning of a beautiful friendship.]
François GM // October 15, 2008 at 1:47 am
What are you talking about ?? Confidence intervals are estimate intervals of a true endpoint, which could be human population parameters, distance to the moon or temperature trends. You don’t apply confidence intervals on the true endpoint but on proxies or measures to estimate the true endpoint. A - 0.1 temp trend from 2001 to 2008 is a -0.1 temp trend from 2001 to 2008 - period. There are NO confidence intervals. It is the true final endpoint, if you define it that way. You may argue that a short-term trend from 2001- 2008 is not a proper TRUE endpoint. Fine. You may then apply statistics (but which ones ??? good luck) to determine the confidence intervals to estimate the TRUE endpoint. But tell us - what is the TRUE endpoint ? Temperature trend from 1980 to 2030 ? From 2000 to 2099 ? Up to you to cherry pick but PELEASE DO NOT apply confidence intervals on the true endpoint.
[Response: My opinion: there's no hope for you.]
Geoff Larsen // October 15, 2008 at 2:01 am
Tamino
I suggest Lomborg’s figures refer to since Jan01 & he may have got them from here (to Jul 08-scroll down to charts): -
http://rankexploits.com/musings/2008/ipcc-central-tendency-of-2ccentury-still-rejected/
or possibly from here (to Aug08-again scroll down to chart):-
http://rankexploits.com/musings/2008/result-of-hypothesis-tests-very-low-confidence-2ccentury-correct/
[Response: I doubt it. He'd have done a better (but not necessarily correct) job.]
george // October 15, 2008 at 2:12 am
It is a well-established fact that Lomborg does not hold up well to close scrutiny, so it is no real surprise that he is again mistaken.
And as far as knowing just how Lomborg got his numbers, I, for one would prefer to remain ignorant of Lomborg’s own ignorance.
I seriously doubt there is anything worthwhile to be learned from it — other than perhaps how NOT to do statistics.
I actually find it more than a little depressing that someone like Lomborg keeps getting public exposure for his opinions, which seem to require almost continual debunking by real scientists.
Harvard biologist Edward O Wilson included Lomborg among what he termed “the parasite load on scholars who earn success through the slow process of peer review and approval.”
http://www.grist.org/advice/books/2001/12/12/point/
Based on what I have seen (eg. Lombog’s book and the response of several scientists to specific claims made in the book made in Scientific American and elsewhere), I have to say that I believe that to be a fairly accurate assessment.
Bob North // October 15, 2008 at 2:32 am
Tamino -
Another possibility you didn’t examine is that Lomborg is referring to the period from Jan 2001 to the present (i.e., part of the first decade of the first decade of the 21st century). This would probably result in a much lower “trend” but I don’t know what it would do to the uncertainty values. Using the period from Jan 2001 would be consistent with his statement that IPCC expected “about 0.2C” for this decade since the IPCC did expect about 0.2C for the first two decades of this century.
Duane Johnson // October 15, 2008 at 3:43 am
None of the decade choices Tamino offers show a warming as large as 0.2C per decade.The degree to which natural variation can explain away this fact depends upon the statistical model that is used, as well as the method of measurement, as well as the method processing the measurements to arrive at the result. Since there hasn’t been a significant volcanic eruption in the period in question, and Tamino’s natural variation includes such effects, the odds are getting slim that the first two decades of the 21st century will in fact have warming as large as 0.2C/decade, whether you start in Jan 2000 0r Jan 2001 or 1998. If a significant volcano should occur, the odds are slimmer still.
I’m pleased to see that Lomborg is questioning IPCC projections. In the past, he has been content to mostly accept their conclusions on temperature while exposing the absurdity of the economic conclusions (e.g. Stern report).
[Response: The statistical analysis is both sound and robust, but it appears we have yet another person who will deny it mainly because he doesn't like the outcome.
I'm no expert in economics, but Stern's credentials are vastly superior to Lomborg's, and what I hear from those who do know the subject is that Lomborg's economics is every bit as bogus as his statistics.]
Philip Machanick // October 15, 2008 at 4:32 am
I suspect some on this page are making the mistake of accepting the claim that Lomborg is a “statistician”. I have yet to track down anything to support this claim. His primary qualifications are in political science (in which he has published at least 2 papers, which makes him hardly more of an authority than me) and though he has worked as a statistics associate prof, I strongly suspect it was in a role of teaching stats to social sciences, as he was working in a political science department at the time. He certainly has not published anything of significance in statistics (or for that matter on climate change, but he has at least written books and copious newspaper articles in that field).
The man is a certifiable bogon and I don’t know why anyone pays attention to him. Just shows how gullible the commercial media are.
Former Skeptic // October 15, 2008 at 5:16 am
That was good analysis on Lomborg’s cherry picking.
I’m actually more interest in Bjorn’s other comment:
“…Likewise, and arguably much more importantly, the heat content of the world’s oceans has been dropping for the past four years where we have measurements. Whereas energy in terms of temperature can disappear relatively easily from the light atmosphere, it is unclear where the heat from global warming should have gone – and certainly this is again much better than expected.”
I assume BL is taking information from Pielke Sr. where Ol’ Roger makes the rather brazen claim that “…global warming has actually halted, for now.” (see http://climatesci.org/2008/09/19/comment-on-the-september-13-2008-article-in-the-economist-adapt-or-die/)
If you click on the relevant link in RPSr.’s post, it brings you to another post that details the source i.e. OHC data from Josh Willis. I’m pretty sure that there’s something wrong with using only 7.5 yrs of upper ocean heat content data to make the conclusion that GW is stopped since 2004. But then again, making such huge leaps of logic has not stopped RPSr in the past (re: The butterfly effect debacle, upper troposphere T, his crazed insistence the UHI seriously contaminates the overall surface T increase…)
PS: A bit off topic, but could this be the moment that Pielke Sr. jumped the shark?
Patrick Hadley // October 15, 2008 at 12:27 pm
One of the good features of this site is the way that Tamino always uses clear illustrations to demonstrate his points.
Why has Tamino not simply shown us graphs of the data from the last decade so that we can see for ourselves what the trend has been?
Surely this is a post that is crying out for some graphs.
void{} // October 15, 2008 at 1:45 pm
Former Skeptic // October 15, 2008 at 5:16 am
Where can I find info re:
“The butterfly effect debacle, …”
Thanks
Ray Ladbury // October 15, 2008 at 2:47 pm
Patrick Hadley, your use of the word “trend” and decade is pretty much inconsistent unless you are interested in trends in the noise. Now you’ve been around here long enough to know this, so one wonders what the point of your post is.
george // October 15, 2008 at 3:03 pm
Patrick asks
There is a significant irony in that statement.
An important (if not central) theme in Tamino’s posts (as I see it, anyway) is that your eyes can fool you.
While graphs are certainly useful in many cases, they can also lead you astray.
“Eyeballing” is simply not a reliable way of determining trends.
That is particularly true for short spans of time, for which any “underlying” trend (due to CO2 increases, for example) can easily be buried in the noise.
Statistics — including the error bar on the calculated trend — is the only way that you can reliably approach the issue.
Unfortunately, for short time spans, it is simply impossible to say what the “actual” trend is with precision because the error bar is large relative to the calculated trend and encompasses a fairly broad range of possible trend values.
That’s precisely why Tamino says above that
[Response: A good summary of the situation. Thanks.]
Former Skeptic // October 15, 2008 at 3:50 pm
Hi void{}:
The relevant thread is here: http://www.realclimate.org/index.php/archives/2008/04/butterflies-tornadoes-and-climate-modelling/langswitch_lang/sp
IMO it’s best read with a steaming cup of java. Ike Solem’s post (#53) is perhaps the best one explaining RPsr’s confusion. Hope that helps!
Patrick Hadley // October 15, 2008 at 4:29 pm
Nobody is going to argue that graphs are on their own sufficient, the fact that Tamino seems to have made the decision that his argument might not be helped by showing us the data on a graph is rather telling.
Perhaps if our eyeballs were shown the data points gradually trending south our brains might not be so receptive to an argument that there is really a trend in the other direction.
[Response: You want graphs? Try this.
Clearly your brain is very receptive to excuses to deny the truth.]
Thomas Huxley // October 15, 2008 at 5:13 pm
Danish Biologist Kåre Foggood exposes Lomborg’s errors in great depth.
David B. Benson // October 15, 2008 at 7:26 pm
Patrick Hadley // October 15, 2008 at 12:27 pm — After reading Tamino’s ‘this’, consider the five and ten year averages from the HadCRUTv3 global surface temperature product:
http://tamino.files.wordpress.com/2007/12/5yrave.jpg
http://tamino.files.wordpress.com/2008/04/10yave.jpg
Gavin's Pussycat // October 15, 2008 at 7:30 pm
Patrick, you can create your own graphs — both those that you like and those that you hate — here.
Cthulhu // October 15, 2008 at 8:53 pm
I’ve noticed that the 10 year window is moving past the 97/98 el nino peak now. Either they’ll switch to using “last 11 years” or “6 years”
September 1998 - September 2008 with trend
http://www.woodfortrees.org/plot/uah/from:1998.6/plot/uah/from:1998.6/trend
And using UAH for the benefit of paranoids.
Steve Bloom // October 15, 2008 at 9:30 pm
Former Skeptic wrote: “(C)ould this be the moment that Pielke Sr. jumped the shark?”
No, but there has been a fairly steady slide downhill since the start of his blog. I suspect the underlying motivation is his perception that the larger climate science world has failed to acknowledge his peculiar (note not denialist as such) views. I suspect there was some major professional disappointment (loss of funding for his RCM?) around the time he began the blog, which was also roughly the same time he retired. He went off the reservation quite abruptly, the details of which are documented in the first six months or so of his blog.
John Mashey // October 15, 2008 at 10:49 pm
Regarding Lomborg being a statistician:
I have a copy of The Skeptical Environmentalist, and both American & British versions of Cool It!
I can’t recall actually seeing any real *statistical* analysis, i.e., the sort of stuff that tamino does so well, or folks from my old place of work like Tukey & Kruskal.
Can anyone point at any real statistical analyses in those books? Perhaps it’s there and I just missed it.
[Note: I don't count just selecting & graphing data as statistical analysis.]
Ray Ladbury // October 16, 2008 at 12:25 am
Hi John, Lomborg’s statistics and analysis always bring to mind some quotes by Andrew Lang:
“He uses statistics as a drunken man uses lampposts - for support rather than illumination”
and
“He missed an invaluable opportunity to hold his tongue.”
John C // October 16, 2008 at 2:22 pm
But isn’t Lomborg actually right ? The decade has been “better than expected” in terms of not having warmed up as much as the IPCC models predicted. I showed the monthly GISS graph graph to my 8 year old son and asked him if he saw it going up, going down or was flat. He said it looked pretty flat. I agree. All the fancy statistics is kind of missing Lomborgs point. Clearly it’s “better than expected”.
And for those of you who think Lomborg is wrong, misguided, stupid or whatever. Maybe you’re right …. but his views certaintly aren’t irrelevant. I guarantee you that more people read the Guardian than read this blog.
[Response: Take a step back, and consider this: I base my characterization of temperature trends on state-of-the-art statistical analysis. You base yours on "I showed the monthly GISS graph graph [sic] to my 8 year old son and asked him…”
Seriously: do you not see a problem with your approach?
In fact you just might have hit the bulls-eye when it comes to characterizing the naivete and folly of Lomborg’s approach. It’s no more sophisticated than what you’ve done.
Furthermore, this post is about the actual numbers Lomborg quotes. Those numbers are bogus, and not just because of naivete — it sure looks to me like Lomborg had to cheat to get ‘em. Your son may not have any knowledge or experience with statistics, but at least he’s being honest.
If your boy had cancer, and the doctors told you that the disease was progressing rapidly but at least he’d been feeling a little better than expected since a week ago Monday, would you rejoice? Would you cancel the scheduled treatment on the basis that ruining the family’s economy was a greater threat? When the doctors protested that it’s expected that he’ll have better days and worse days because of random fluctuations in patient condition, that his ten-day “feeling better” episode was absolutely zero evidence of a change in the underlying trend, and that if you stop treatment he’ll never see his 9th birthday — would you go to his best 8-yr-old friend to get a second opinion?]
Dano // October 16, 2008 at 5:44 pm
Tamino, RE your reply to John C, it depends upon whether he chooses to deny the advice of experts.
Best,
D
Ray Ladbury // October 16, 2008 at 7:25 pm
John C., I think the key words in your post are “than expected”. Expectation implies we have some sort of model. It implies that we know how it is likely to behave. In the case of climate, an inherent feature is noise. So as long as the behavior is not well outside of what we would expect given known trends + noise, then the behavior is as expected. Now contrast this with a model that assumes noise alone without anthropogenic warming and see how out of the norm the past 30 years are.
[Response: Excellent point; the "apparent flat trend" is most certainly NOT outside expectation. That's the theme of this post.]
Anna Haynes // October 16, 2008 at 8:04 pm
I’ve emailed the following to Dr. Lomborg’s personal assistant:
_______
Greetings Zsuzsa Horvath -
Questions have arisen at the climate blog Open Mind, here -
http://tamino.wordpress.com/2008/10/14/bjorn-lomborg-how-did-you-get-those-numbers
… as to what dataset(s) Dr. Lomborg drew his conclusions from, for his recent Guardian article, that
“[It] is true for all surface temperature measures, and even more so for both satellite measures [that] Temperatures in this decade have not been worse than expected; in fact, they have not even been increasing. They have actually decreased by between 0.01 and 0.1C per decade. ”
Could you please check with Dr. Lomborg and let me know what dataset he used and how he arrived at this conclusion, and/or post the answer as a comment to the Open Mind blog post?
_______
Dave A // October 16, 2008 at 10:51 pm
Ray,
Your faith in climate models is truly, truly touching. If only everyone could have such belief!
JCH // October 16, 2008 at 11:07 pm
Oh boy, this going to be precious.
Ray Ladbury // October 17, 2008 at 12:25 am
Gee, Dave, maybe that’s because I actually understand them to some extent.
Look, Dave, two types of people come to blogs like this–people who are trying to understand the science and pudknockers. Want to learn some science? Great. Join the rest of us. Want to revolutionize climate science. That’s great, too. Publish something in a peer reviewed journal that actually furthers undestanding of climate. Otherwise…enjoy your solitary activity.
Charles // October 17, 2008 at 11:16 am
Tamino, I very much enjoyed and appreciated the analogy you used in replying to John C. I suspect that analogy will make the rounds. Thanks.
John C // October 17, 2008 at 12:59 pm
I agree that the two approaches (’eye ball’ and ’state of the art’ statistics) are clearly different .. but the result is the same. However you want to look at it … the last decade has not seen a 0.2 degree rise - so ‘better than expected’.
[Response: Wrong. If the underlying trend is 0.2 deg.C per decade, then we do NOT expect exactly 0.2 deg.C rise in a single decade -- what we expect is somewhere within a range of values centered on 0.2. And that's the point: the observed value is within expectation.
Your argument is like saying that if you flip a fair coin 100 times we expect to get 50 heads and 50 tails, so if we only got 49 heads then the result is outside "expectation." NOT TRUE. What we expect from 100 coin flips is somewhere between 40 and 60 heads. The observed result is well within expectation.]
Your point that this may be irrelevant in the big scheme of things is, course, true …… the charming cancer analogy ….. but that wasn’t the point of Lomborgs article. And indeed, in answer to Ray Ladbury, on the issue of trend and noise, and a flat period being ‘not unexpected’ …. all true. Which is why it’s such a SHAME that the flat period falls outside the entire uncertainty range of the IPCC 2001 models (p34 of the Sum. for Policy Makers). I guess they never EXPECTED that there MIGHT ever be a flat period. How did that happen with so many modelling experts ? Hence the truth of Dave A.’s comment. I think they must now recognise their error as they have significantly increased the uncertainty range in the 2007 report.
It think Lomborg made an error in quoting some numbers because they are irrlevant and only result in him being correctly criticised for not stating where they came from. It detracts the main thrust of his article - he didn’t need to do it. Maybe Anna Haynes will get an answer
[Response: Lomborg did more than make an error. He cheated. And the numbers are not irrelevant because he's deliberately shrunk the range to make it seem that observation is outside that range.
As for the "charming" analogy, maybe that's what it takes to get you to take this seriously. After all, this is a problem that unfolds on time scales of decades, not years; your son is at far greater risk from global warming than you or I. His health and happiness, even his life, could be at stake: THAT'S HOW SERIOUS THIS IS. I'm sure you care deeply about his future -- so for his sake, stop getting suckered by con artists.]
Ray Ladbury // October 17, 2008 at 2:27 pm
John C., Let me guess, you’re one of those whose stock strategy is buy high and sell low, right? If all you look at is the current short-term trend, ignoring the long-term rise since 1750, the physics , the dramatic rise since 1975, the paleoclimate, etc., then I’d have a hard time imagining you looking at long-term stock trends.
Produce one quote by the IPCC that precludes the sort of trend we’ve seen.
Anna Haynes // October 17, 2008 at 3:39 pm
Response from Lomborg’s personal assistant Zsuzsa Horvath, re source of L’s statement on temperatures “They have actually decreased by between 0.01 and 0.1C per decade”:
———–
The temperature measurements from Jan 2001 to Aug 2008 from http://rankexploits.com/musings/2008/result-of-hypothesis-tests-very-low-confidence-2ccentury-correct/
———–
[Response: Does anyone else consider it outright dishonesty for Lomborg to base his "better than expected" claim on a blog post which states outright that a 0.2 deg.C/decade trend is NOT contradicted by statistical tests?]
Hank Roberts // October 17, 2008 at 4:00 pm
As though “actually” meant something real. D’oh.
boulderSolar // October 17, 2008 at 5:28 pm
Tamino,
So Lomberg uses as his reference a reasonably respected website that matches the numbers he uses in his article. Furthermore the website author, an astute and competent statistician, makes the conclusion that there is a “very low confidence” (<10% chance) that the .2 deg/decade projection is correct. Now you accuse him of being dishonest because the probability is not less than 5%. Lomborg never states that the projection is statistically falsified, rather he is pointing out the recent temperature trend is better than expected. He has a good (and correct!) point in that recent temperature trends are better than expected; to the level that the IPCC projection is getting darn close to be statistically falsified. Are you meeting your standard of honesty that you are imposing on others?
[Response: Lomborg states that the trend is declining at between 0.1 and 0.01 deg.C/decade. This is based on the range exhibited by different data sets; it takes absolutely NO account of the uncertainty in any one of the estimates, which is quite a bit larger than the range between the different data sets (which are not independent data sets).
As to "darn close to be statistically falsified," even that result, dependent on a specific cherry-choice of starting time, only manages to come close. Choosing a start time which favors one's own hypothesis (and Lucia has tried darn hard to falsify the IPCC projection) alters the statistics of the result even further -- but neither Lucia nor anyone else I can find has taken that into account.
And again: you are WRONG: recent trends are NOT outside expectation, they are well within the expected range given the size and character of the noise. Considering that even a cherry-picked starting date fails to contradict a trend of 0.2/decade, that's a very strong denial of the thesis that the trend is less.
There's one clear conclusion from all this: those who want to believe what's false will not be swayed by reason.]
george // October 17, 2008 at 5:58 pm
The fact that Lomborg went to such (short) lengths to get a trend to his liking basically says it all.
Hank Roberts // October 17, 2008 at 7:56 pm
george wrote:
> went to such (short) lengths
> to get a trend to his liking
Devastating, funny, terse. Good sharp point.
David B. Benson // October 17, 2008 at 9:07 pm
What Hank Roberts just wrote.
Dave A // October 17, 2008 at 9:22 pm
Ray,
Believe me I am trying to understand the science - its just that there are all these holes everywhere.
Not hailing from your neck of the woods I can still probably guess what you mean by “pudknocker”. If I was that it still might be better than being a” true believer”
tamino // October 17, 2008 at 9:25 pm
After considering the source of Lomborg’s numbers, I’ve concluded that he might not have been deliberately misleading in his atrociously wrong statement. He might actually believe he’s correct.
Which raises a very important point. Lomborg titles his article, “Let the data speak for itself.” The problem is, the data are numbers, and that’s a language that most people, frankly, don’t understand very well. It’s like saying “let the accused speak for himself” in a criminal trial, when the accused speaks only Chinese but the judge, jury, and attorneys don’t understand a word of it and no interpreter is available.
So if he wants to let the data speak for itself, then he needs to find a competent interpreter. If Lomborg isn’t being deliberatly misleading, then he’s sufficiently innumerate that he’s the wrong spokesman for the data.
Ray Ladbury // October 17, 2008 at 9:35 pm
boulderSolar, Now take a minute and step back to think about what you are defending: Lomborg took cherry-picked dates designed to give the absolute lowest trend he could and still it only ALMOST statistically falsified. Is that really what you consider a defensible position: “well, he almost wasn’t lying. “
Lazar // October 17, 2008 at 9:52 pm
Tamino,
It seems he’s taken the exact slope from the NOAA data and the exact slope from HadCRUT as the minumum and maximum of his range. Also, that lucia has used those slopes as exact figures and put the observational error on the 2 degC/century purportedly estimated from GCMs. It appears there is no estimate of GCM error variance.
Ray Ladbury // October 17, 2008 at 9:54 pm
Dave A., what I am is a scientist. That means that when it comes to what I believe, I have to side with the preponderance of the evidence–and virtually all the evidence (as well as the physics) supports anthropogenic causation. If you want to understand scientific belief, then I urge you to read:
http://ptonline.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=PHTOAD000060000001000008000001&idtype=cvips
See, unlike you, I can’t just decide to not believe in climate change because I don’t like what it means for my lifestyle. The very same factors that imply anthropogenic causation are absolutely essential to understand paleoclimate, weather, the origins of life, past extinctions, recoveries and on and on. To me and other scientists understanding what is going on in the world is important. That is why you find so few scientists who really understand the theories among the skeptics.
You claim there are gaps. There are always gaps–but I suspect most of the gaps you see are illusions that arise from your lack of understanding of the science. And this is what I don’t understand about people like you: You are surrounded here and at RC by people who actually understand the science, and yet rather than trying to gain understanding of the science, you persist in attacking your straw men. This is an absurd waste of time on two levels. One, you’re not even attacking the real science. Two, attacking the science here is like burning an art book because you don’t like cubism. This isn’t where the science gets done. And the only way you are going to see the science change is if some new theory comes along that explains the data better. To date, denialists have proposed precisely bupkis. That is why they and you are irrelevant.
Dave A // October 17, 2008 at 10:51 pm
Ray,
Perhaps I have touched a raw nerve?
Two points,
First my questions about climate change have nothing to do with my lifestyle or how that might change. After all, I wouldn’t frequent this and similar blogs if I was into lifestyle would I?
Second, as a person I don’t think I am “irrelevant” and you have no right to say that
George Ray // October 18, 2008 at 12:18 am
Tamino,
You said that Lomborg has cherry picked the starting date. What date would you have picked to do the analysis? What statistical methodology would you use to support picking the start date? I believe in AGW and am trying to get my head around the application of the stats.
Thanks
[Response: I'd have picked 1975. That's based on studying the entire time span of temperature data and attempting to find the smallest set of straight-line segments which would approximate the temperatures, such that the residuals from that "multi-linear" fit don't show unambiguous deviation from being a random series. So far, I haven't seen any evidence that the data since 1975 are any different from a linear trend plus ARMA(1,1) noise. You can view the residuals from a linear fit for data from 1975-present, for estimates from GISS, HadCRU, and NCDC, here.
It's legitimate to choose other starting dates, BUT they must NOT be chosen in order to achieve some desired result. Also, the more starting dates you "try," the greater chance of getting a large (positive or negative) trend rate just by *chance* -- so the statistics have to be modified to account for that.
And of course, you have to apply the statistics in the first place in order to estimate the uncertainty in the result you get.
Even applying the ARMA(1,1) model (which seems to be appropriate) to the random part in order to estimate the uncertainty, in order to be completely rigorous one must account for the uncertainty in the estimated *parameters* of the ARMA(1,1) model; it means that the actual uncertainty is a bit larger than computed here.
Lucia and Lomborg have also mischaracterized the IPCC projection; there's more information about that here.]
Former Skeptic // October 18, 2008 at 12:18 am
Steve Bloom:
Thanks for the succinct summary. I didn’t know about the suspicions of his professional disappointment around the commencement of Climate Science…which now make sense. Personally I think he has recently jumped/or is currently jumping the shark, especially with his recent bizarre insistence that GW has halted since 2004 based on (AFAIK) analysis from unpublished upper OHC data.
Anyway, back to the topic at hand. Lomborg, ostensibly an adjunct professor, has a personal assistant?? Wow. Talk about style overcoming substance.
Ray Ladbury // October 18, 2008 at 1:32 am
Dave A., Actually, I could not give a rat’s posterior what you think of me–and if you are going to make assumptions about my character and motivations, I’m certainly justified in making assumptions about yours. Certainly, your entire line of argument since coming on here seems to be directed at maintaining rather than updating your beliefs. You have yet to ask a question that you really wanted to know the answer to.
Your irrelevance in the climate debate is voluntary. It derives from your decision to reject sound science and abandon your place at the negotiating table where we decide what to do about the threats posed by climate change. You’d rather debate science you don’t understand than learn the science. And the science is solid. It won’t change because you don’t like it. So the only possible place for folks like you and me (I am not a climate scientist–just a physicist) is where we decide how to confront the threats. That is why I spend time here, at RC and other places where I can learn more about the science–so that I can exercise that responsibility in a knowledgeable fashion. On the other hand, you’d rather bloviate your misunderstandings in places where they have no effect whatsoever. Fine. Good luck with that.
Ray Ladbury // October 18, 2008 at 2:12 am
Tamino’s point about data being a foreign language to most people is important. I would contend what is more that without a physical theory in which to interpret the data, they won’t be very illiminating. It is true that physical understanding can come from the data, but it still has to come by way of a theory. In the absence of physical understanding you wind up with what I call “weather watchers”–the “alarmists” who raise the alarm to a shrill pitch each time you have an El Nino or a big hurricane and the denialists who look for any slight drop in temperature to proclaim that “warming has ended”.
The prediction of warming predates the era where it was obvious. When it was not seen, scientists looked for other factors. They didn’t find any that haven’t been known since the 30s or 40s. This is not a science in its infancy.
Duane Johnson // October 18, 2008 at 3:10 am
Ray,
How much does one learn about a science by being a sycophant for those holding a particular point of view? Does it earn you a place at the table for making those major decisions?
Honestly, have you spent any time reading Lucia’s blog? She is attacking the question of temperature anomoly trends in a rational way, which leads her to the conclusion that a 2C/century trend since Jan. 1, 2001 is “very unlikely” using terminology adopted and used by the IPCC. And incidentally, the 2001 date was not chosen to produce the minimum trend, and in fact it doesn’t, but you’d have to read her blog to know that. She and Tamino have had some interesting and informative exchanges, reach some different conclusions, but the net result is instructive as well as constructive to the issue.
I always look forward to what Tamino has to say about her analyses, and the converse is also true.
matt // October 18, 2008 at 4:31 am
Ray Ladbury: And the only way you are going to see the science change is if some new theory comes along that explains the data better. To date, denialists have proposed precisely bupkis. That is why they and you are irrelevant.
Lack of a correct theory doesn’t make the current AGW theory any more or less correct. You know that. And there’s no need to be a jacka$$ to the guy. I suspect Hansen would have called anyone that stated we’d be below Scenario C “irrelevant”….and yet here we are.
Elsewhere you note…This is not a science in its infancy.
It might not be a science in its infancy, but it’s certainly not mature, and pretending that folks have a firm grasp on how this works with any certainty is laughable.
Aerospace engineering is about 100 years old, about the same amount of time since Arrhenius and others first thought about this. Understanding the mechanics required to successfully model flight is a much simpler problem than understanding and modeling climate. And there has been orders of more magnitude devoted to understand the machanics of flight and everything that goes into that (materials, propulsion, etc). Thus, we are at a point today where after a staggering investment, we are able to reliably model the mechanics of flight with great accuracy.
Thus, by definition, our understanding and modeling of climate climate is quite poor (orders of magnitude less) when you compare it to our ability to model and understand things that are quite a bit simpler (integrated circuits, flight, etc).
michel // October 18, 2008 at 5:31 am
Lucia has tried darn hard to falsify the IPCC projection
The implication is that she has an agenda other than simply establishing whether the IPCC projection is supported by the evidence.
First, I see no sign that she does. She seems to be following the data wherever it leads. She picked the start of her data series for the excellent reason that she wished, when dealing with predictions, to be dealing with predictions which predicted what was in the future at the time they were made. This is perfectly reasonable.
Second, even if she were pursuing the subject with a view to falsifying the IPCC projections, this would not touch on the validity of her research. It does not matter a bit why she is doing it. What matters is whether she is doing it right. Many of the great discoveries in science have been made because the discoverer set out to falsify an hypothesis, and either succeeded or failed, with startling results.
All too often in this blog it is thought sufficient to dismiss an argument by casting aspersions on the motivation of the one putting it forwards. These remarks only lessen the credibility of the one making them. As in this case.
John C // October 18, 2008 at 5:36 am
Ray Ladbury wrote :
Produce one quote by the IPCC that precludes the sort of trend we’ve seen.
As I already wrote (I hate having to repeat myself) … see p34 of the IPCC2001 report Summary for Policy makers. Link below in case you can’t find it.
http://www.ipcc.ch/pdf/climate-changes-2001/synthesis-spm/synthesis-spm-en.pdf
As you can see, and if you actually plot the global temperatures up to 2008 on this graph, this little ‘flat’ period falls below the ENTIRE RANGE of scenarios (those are the different coloured lines) and below the ENTIRE ENVELOPE of uncertainty (thats the shaded grey area - and is stated as the 95% confidence limit). So clearly this little flat period falls below anything they might have expected (even in their wildest dreams) …. otherwise they would have used a bigger range.
Sometimes a picture speaks a thousand words. You did ask though….
[Response: The graph on pg. 34 of that link doesn't seem to support your claim. I think you've been very thoroughly brainwashed into believing it.
You need to give this a good read.]
cce // October 18, 2008 at 5:51 am
Here’s a math problem for Lucia’s supporters. Does the observed trend from January 2001 to September 2008 “falsify” (at the 95% level) the observed trend from January 1979 to September 2008?
hswiseman // October 18, 2008 at 6:43 am
Choose 1975 and stand at the precipice of the big PDO switch, end your time series in 1999 and capture the super elnino, start in 2001 and dodge it. Infer motives against every selection. Avoid fundamental questions (stationary/non stationary/negative-positive feedback), perform science for the purpose of expanding the CI instead of improving the methods and quality of obs. This is what is being taught at the places that teach this science, pearls of wisdom such as poor old Pielke and “his crazed insistence the UHI seriously contaminates the overall surface T increase”, “I suspect there was some major professional disappointment (loss of funding for his RCM?) …”
You all do it so well…and with so little embarrassment.
Ray Ladbury // October 18, 2008 at 11:13 am
Duane Johnson,
OK, now let me get this straight. You equate trying to learn the science with sycophancy?
Hey, whatever, Dude. So how’s the ignorance thing working out for you, then?
I’ve looked at Lucia, but I do not find her analysis at all persuasive. To draw any conclusions based on a short time-series when the noise can dwarf the signal on such timescales is questionable to say the least. To extrapolate that to a century timescale is risible. What Lucia is doing in this case is weather watching. She is much more interesting when she applies her skills to a meaningful dataset.
When it comes to making policy, you have to go with the best science available. Not satisfied with that science? Then get a climate science PhD and publish something that does a better job. Otherwise, your opinion isn’t part of the scientific debate. It is still relevant in the “What do we do about it?” debate, but by rejecting good science, all you do is skip the main event to take in a side show.
Now, I could go on, but given your dismissive attitude toward learning science, I don’t see much point in wasting more of my time on you. And good luck with the ignorance thing.
michel // October 18, 2008 at 1:05 pm
Here’s a math problem for Lucia’s supporters. Does the observed trend from January 2001 to September 2008 “falsify” (at the 95% level) the observed trend from January 1979 to September 2008?
No. And its not a math problem. There are two sets of observations, neither of which can falsify the other. They are what they are. What the trend is from 1975 on is a different question from the one Lucia is addressing. It may be a more interesting question, at least to some. But whether it is or is not, is irrelevant to whether she is addressing her chosen question correctly.
I do not count myself as a ’supporter’ of Lucia in the sense that there is some general overall position which she is maintaining on AGW or the IPCC which commands my assent. I am a supporter in the sense that I find her work both competent and creative, on the subjects she has chosen. I’m a supporter also in that, like Lucia, I am very interested in both the methodology and the results of her careful analysis of the validity of IPCC predictions of temperatures post 2001. That is, the IPCC in 2000 made some predictions of temperatureswhich were at the time in the future. Have they been borne out by subsequent events, and if so, to what extent? This is a restricted but legitimate question, and one which lots of us want to know the answer to.
You can’t say anything useful about her results on this by telling her she should be addressing a different question. Any more than you can by impugning her motives.
Ray Ladbury // October 18, 2008 at 2:33 pm
Matt, First, is it too much to ask you guys to learn the difference between a prediction and a scenario. The best the scenario can do is give the overall trend to be expected–every single model run will be different. There is no meaningful trend that can be extracted from 7 or 8 years of data.
Second, hmm, lack of a correct model, huh? We wouldn’t be referring to the only model by which we can understand a 2o year warming trend, the paleoclimate, the response of the climate system to volcanic eruptions and perturbations like the hiatus in global air traffic and numerous other pieces of evidence, would we? I’d call that a pretty successful model. What is more, the conclusion on anthropogenic causation is predicated on aspects of the theory about as basic as Bernoulli’s equations. Why not try to learn the science, so that you at least are not trying to demolish a straw man?
As to Dave A., if you look at our full correspondence, I would contend that I have shown astounding forbearance. For instance, despite being called a “true believer” by someone who clearly has made zero effort to understand the science, not once did I suggest that he was an ignorant food tube.
As to the accusation of irrelevance–can you think of anything more irrelevant than flogging away against a blog that merely tries to teach the science while the science continues to progress far, far away in academic journals, oblivious of your flailings. Contrary to what Ms. Pailin asserts, causes do matter. The science has been reviewed and found cogent by scientific and professional sciences from the National Academies to the American Institute of Petroleum Geologists. Perhaps if you learn more about it, you will find it cogent as well. Then you can exercise your responsibility as a citizen and look for solutions that are consistent with what you value.
Raven // October 18, 2008 at 3:22 pm
Ray says:
“I’ve looked at Lucia, but I do not find her analysis at all persuasive. To draw any conclusions based on a short time-series when the noise can dwarf the signal on such timescales is questionable to say the least. ”
There is no magic interval that seperates climate from weather. The only reason to use longer periods is the CIs decrease with longer periods so it is easier to distinguish between hypotheses. There is absolutely nothing that says cannot measure climate trends over shorter intervals provided one chooses the appropriate CIs. In most cases, the this means that results are too uncertain to tell us anything useful, however, sometimes the trends are so significant that it is possible to reject some hypotheses even if the CIs are wide. That is what Lucia has demonstrated. At this point in time we can safely assumes that either:
1) The sun has a much greater effect than what was previously claimed by the models.
2) The models over estimate the amount of warming from CO2.
So feel free to quibble about Lucia’s choice of CIs, however, insisting that it is ‘impossible’ to analyze climate over shorter time scales makes no sense from a statistical or scientific perspective.
cce // October 18, 2008 at 3:41 pm
Anyone who claims to have “falsified” the IPCC projections, which are ensemble means that eliminate natural variability, based on ~8 years of data is not interested in correct methodology. She has been repeatedly told this, yet she insists on mischaracterizing the IPCC projections. Gavin posted the results of 55 model runs that went into a scenario from AR4. 9 of them (~16%) showed flat or cooling temperatures from 2001 to 2007. She can keep saying that the projections have been “falsified at the 95% level” all she wants, but it has no bearing on the facts.
Duane Johnson // October 18, 2008 at 3:59 pm
Ray,
I consider sycophancy to be obeisance to some entity, in order to gain perceived benefit.
You haven’t understood Lucia’s analysis, since the heart of her analysis is to evaluate the variability (you call it noise) in the weather data from historic data from periods that excude major volcanic data. She is not ignoring the weather variability, but is evaluating the extent to which it can explain the validity of a particular (2C/century) from Jan 2001. As Tamino has noted, she doesn’t find, based on GISS data that 2C/century can be excluded at a 95% confidence level. However, her analysis does so at a 90% level, which the IPCC categorized as a very low level of confidence in their advice to policy makers. Her analysis is subject to caveats, which she openly states.
And she doesn’t claim the duration of the trend is for a century, only for the first portion of the 21st century as projected by the IPCC.
Tamino and others with the necessary statistical experise can and will critique the analysis, and we can all learn from it.
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