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IPCC on climate sensitivity

Nic Lewis, best known as one of the co-authors of the O'Donnell et al paper on Antarctic temperatures has a must-read post up at Judith Curry's place. The title tells you all you need to know:

The IPCC’s alteration of Forster & Gregory’s model-independent climate sensitivity results.

This is pretty shocking stuff.


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Reader Comments (141)

Just a small point. Both Forster and Gregory (my friends Piers and Jonathan) were contributing authors on chapter 9 of IPCC AR4 WG1 which is being said to have misrepresented their results, and they were also involved in a major way elsewhere in the report (Piers was CLA of chapter 2 and Jonathan was an LA in another chapter, can't remember which) so one would assume that they were happy with what the chapter 9 lead authors did.

Jul 6, 2011 at 12:11 AM | Unregistered CommenterRichard Betts


My summary would be...

A statistical analysis essentially combines a researcher's "prior beliefs" with the "observed data" to generate an answer. If, as a researcher, you do not have any preconceived notion of the right answer, you try to have as weak as possible "prior beliefs" so as to let the data itself determine the answer.

The original paper attempted to have very weak prior beliefs regarding the actual climate sensitivity and got a relatively low range of climate sensitivities (with a 95% confidence range that had a middle value of 1.6 deg C per doubling and a high value of 4.1 degree C per doubling).

When the IPCC reported the analysis, they CHANGED the priors to a STRONG belief in high climate sensitivity. The IPCC priors assumed that potential climate sensitivity ranged from 0 to 18.5 deg C, and that everything in this range is EQUALLY LIKELY. Essentially, the data is fighting against a built in belief that median sensitivity is 9.25 deg C per doubling.

The result of the change in prior was to pull the answer away from the data and towards a much higher range of climate sensitivity (with a 95% confidence range that had a middle value of 2.3 deg C per doubling and a high value of 8.6 degree C per doubling).

In statistics, one always has a prior (although many times people don't realize they have an implicit prior). Unfortunately, through manipulation of the prior, one can generate virtually any desired answer. However, taking a peer reviewed article -- which argued for a particular prior -- and fundamentally changing that well argued prior seems beyond the pale at this point.


Jul 6, 2011 at 12:18 AM | Unregistered CommenterJames

Nic Lewis, if he is correct, definitely deserves a McIntyre McKitrick Award.

meanwhile, another battle is raging:

5 July: Reuters:Pete Harrison: Europe and US airlines clash in court over emissions
U.S. airlines make court challenge to EU carbon market
Airlines charge that EU rules breach U.S. sovereignty
China criticised the scheme on Tuesday , adding to fears of a brewing trade war.
The Air Transport Association of America (ATA) mounted its challenge to the EU on two main fronts -- that its climate regulations breached U.S. sovereignty, and secondly that they comprised an illegal charge under the main international treaty on air travel, the Chicago Convention...
"The EU does not have competence to regulate third country airlines in third country airspace," Derrick Wyatt, a lawyer for ATA, told the European Court of Justice in Luxembourg.
"It is astonishing that a U.S. airline must acquire an EU licence to cover emissions at a U.S. airport."...
(European Commission lawyer Eric White) "The claimants seem to think that extra-territoriality equals illegality -- of course that's not the case," he added...
Environmentalists said global talks to find a solution to aviation's emissions had dragged on for 14 years, and airlines should not attack the only meaningful piece of regulation.
"Instead of flying planeloads of lawyers to Europe, the aviation industry should face up to its future and get on with the job of cutting emissions," said Bill Hemmings of green transport campaigners T&E.

Jul 6, 2011 at 1:09 AM | Unregistered Commenterpat

Jul 6, 2011 at 12:11 AM | Richard Betts

my friends Piers and Jonathan

You know, Richard, that does not really speak well for your friends Piers and Jonathan. I think I would prefer to have one of them come here and defend this in terms that make scientific and statistical sense. They may well be happy with the IPCC treatment because it means they are not kicked out of the club, the way Judith Curry has been. Sheesh. "The numbers? They don't matter. I'm perfectly happy with the IPPC presentation. It's the narrative that matters. We're saving the world, doncha know?"

Jul 6, 2011 at 1:18 AM | Unregistered CommenterRobert E. Phelan

Someone earlier talked about the elephant in the room, may I suggest that there is a freaking mamoth in the room? Where in all these discussions about feedbacks and forcings is the fact that the relationship between CO2 and temperature is logarithmic and not linear. Currently CO2 ppm is rising but temperature is not rising?
I am boring in the xtreme on this forum because I insist that talking about tiny areas of science is less useful than looking at the "big pictuire". Much of the science is disputed but much empirical evidence is undisputed so why worry about the science?
Good old Bob Watson says that "adding CO2 to the atmospher must cause warming, its simple physics"
The logarithmic relationship between CO2 and temperature which is recorded in in AR3 means that at some point adding CO2 to the atmosphere will have no effect. What is that point? Does anybody care?

Jul 6, 2011 at 2:02 AM | Unregistered CommenterDung

The real question is, who exactly altered it and who knew about or was involved in that decision?

Jul 6, 2011 at 2:27 AM | Unregistered Commenteredward getty

edward getty,

It's Howard Baker who is famous for crafting the question -- "What did they know and when did they know it?"

Jul 6, 2011 at 3:03 AM | Unregistered Commenterstan

My guess is that the changes were done by or under the supervision of Coordinating Lead Authors Hegerl and Zwiers. Figure 9.20 is said to be in the style of Hegerl et al 2006 (coauthor Zwiers), where uniform priors were applied.

IPCC review procedures permits Lead Authors to ignore review comments. Hegerl and Zwiers ignored Annan's critical review comments.

Jul 6, 2011 at 3:06 AM | Unregistered CommenterSteve McIntyre

"we need a McIntyre Prize"

I have already seen McIntyre used as a verb "to McIntyre" or "he's been McIntyred" meaning his conclusions have been closely audited and found to be based on spurious data or methods.

Jul 6, 2011 at 4:16 AM | Unregistered CommenterJT

I came across this comment by Judith Curry in a debate on her blog concerning a paper that blames the current lack of global warming on aerosols produced by those dastardly coal burning Chinese!

Prof. Judith Curry: ''The political consequence of this study seems to be that the simplest solution to global warming is for the Chinese to burn more coal, which they intend to do anyway'

Jul 6, 2011 at 6:42 AM | Unregistered CommenterGordon Walker

Richard Betts @ 12.11AM
"so one would assume that they were happy with what the chapter 9 lead authors did." I would assume nothing. I would want to see the evidence that they were happy. In light of what Steve McIntyre has said, they probably had no say in the final version. Most comments seem to be either ignored, rejected or reinterpreted by the lead authors.

Jul 6, 2011 at 7:01 AM | Unregistered CommenterPhillip Bratby

For anyone reading the notes Steve posted at CA, note 9-875 has nothing to do with this, but had me grinning widely. "feebacks > feedbacks" indeed! I thought it was vice versa.

Jul 6, 2011 at 7:37 AM | Unregistered CommenterGeoff Cruickshank

I am still trying to work my way through the math involved but I would ask, as others have done, what the statement "So what did the IPCC do to the original Forster/Gregory 06 results" means.

My understanding is that the IPCC is there as a collection point for the science involved. The IPCC is a U.N. group. In other words, who the **** is actually responsible for what has occurred to the original paper? Who allowed the person/people to make the changes? Why were they not challenged?

I begin to think that the word "Robust" is about to get an updated definition in the old Oxford English dictionary!

Nic Lewis...thanks! More math to gen up on ! ;-)

Jul 6, 2011 at 8:42 AM | Unregistered CommenterPete H

Re: Richard Betts
> so one would assume that they were happy with what the chapter 9 lead authors did.

It is irrelevant whether the authors are happy or not.

Their peer reviewed paper came up with the result, using the methods detailed in the paper, that climate sensitivity was between 1.0 and 4.1°C, with 95% certainty with a median of 1.6C.

The IPCC ignored the methods in the paper and used their own methods, which have not been peer reviewed for the data set they used them on, and came up with a climate sensitivity between 1.2 to 7.9C with 90% certainty and with a median 2.3C.

There is no support for this claim in the peer reviewed literature. The paper they cite (Forster and Gregory) does not support this conclusion.

Jul 6, 2011 at 9:14 AM | Unregistered CommenterTerryS

The major uplift in coal usage in China only started in 2004, shouldn't that have needed to have been earlier to fit the (useless) AGW theory offset by areosols.

Unless coal fumes are transportable by time machines that is.

Jul 6, 2011 at 9:43 AM | Unregistered CommenterBreath of Fresh Air

Here's my try at a simple explanation of Nic Lewis's work:

Forster and Gregory's study was an attempt to measure climate sensitivity by examining the link between the earth's surface temperature, and the radiation reflected or emitted by the earth's atmosphere ("net outgoing radiative flux"). This amounts to a measure of the effectiveness of the greenhouse effect: outgoing radiation increases if the top of the atmosphere gets warmer. So, if the surface of earth gets warmer, but outgoing radiation does not increase much, that means that the greenhouse effect has got stronger. If, on the other hand, outgoing radiation increases quite a lot, then the greenhouse effect has not got stronger: the surface of earth got warmer, but so did the top of the atmosphere. The ratio of the increase in outgoing radiation to the change in temperature is called the "overall climate response or feedback parameter" and denoted Y. If Y is big, then the earth is good at emitting more heat if its surface warms a bit, and AGW should not be too severe.

How do you measure Y? Well, it is not easy because you only get to observe small changes of fractions of a degree of the earth's temperature, and the measurement of the outgoing radiation has error bars. So you don't just get a nice tidy number for Y, you get a range of possible values. The most likely number for Y, given the observations, was determined to be 2.3 - quite large, consistent with some warming due to CO2, but not a lot. The data also provides an estimate of how likely it is that 2.3 is wrong, and that the value is instead 1.0, or 3.6, or whatever. That gives a "probability distribution function" for Y, showing the relative probability of each conceivable value of Y. This function is Fig. 2 of Nic Lewis's post. 2.3 gives the largest value - this is the most likely value of Y, but the probability of rather different values is not all that much smaller. E.g. 1.4 and 3.2 are each about half as likely as 2.3. In other words, the probability distribution functions is quite broad, reflecting how hard it is to measure Y accurately. Note, and this is important, that the whole probability distribution function is the result of the work by Forster and Gregory. Note also that it is not easy to estimate the shape of the probability distribution function, just as it is not easy to determine the most likely value for Y. But Forster and Gregory's estimate is the one they felt reflected the observations in the best way.

Y also determines the climate sensitivity - how much the earth would warm up if CO2 doubled, noted "S". As I wrote above, big Y means small S, and in maths, S simply equals 3.7 / Y in the units used. Using the measurements, you can then get a probability distribution function for S - and that is Figure 3 of Nic's post. One way of reading this is to add up all the probabilities falling within a certain range of values of S, which allows you to say things like "The measurements suggest that there is 17% chance that S is larger than 2.3", or "there is 95% chance that S is between 1.0 and 4.1". Again, these values are reasonably reassuring - the chance of very large warming (S > 3.0) is fairly small.

The IPCC did not report Forster & Gregory's distribution function for S in the way it is shown in Fig. 3 of Nic's post - instead they showed it as the blue curve in his Fig. 4, which has a very different shape (the original is shown in green), and suggests an uncomfortably larger probability for values of S that would correspond to significant extra warming. As mentioned in this comment by Nic on his own post, this curve enables people like Vicky Pope from the UK Met Office to say that small, safer, values of S have effectively been ruled out.

So how did the curve change shape? Well, the authors of the IPCC chapter (including Forster and Gregory) decided that the probability distribution function for Y that Forster and Gregory had come up with was wrong. The reasons for this are pretty technical and revolve around decisions about how one thinks the errors in the measurements pan out. As seen from Nic's Figure 2, the original analysis had concluded that errors in Y were symmetric, in that they were just as likely to have got a value of Y that was too small as to have got one that was too large. But the IPCC authors decided that the pattern of errors was different - that it was more likely, all things being equal, that Forster and Gregory had a value of Y that was too big, than that they had a value that was too small. They changed the probability distribution function for Y to look like the pink curve in Figure 6 (the original curve is shown in brown). This looks like a big change, and it is a big change!

On the one hand, the measurement is not that easy to make, and it is also difficult to work out what the shape of the probability distribution function for Y and S should look like. So there is a way to analyze the data and conclude with some reason that the new distribution functions make sense. To understand how this can arise, it is necessary to realize that not all problems in statistics and probability are simple ones where you can estimate likely probability distributions easily. We all intuitively know that we have one chance in 6 of throwing a 3 with a fair dice. But in other cases, like the Bertrand Paradox that the Oxbridge Prat linked to above, where we need to guess whether a 'random' line drawn within a circle will be longer or shorter than another line, our instincts are less secure, and it turns out that the answer depends on what exactly we mean by "random". Certainly, Forster and Gregory's measurements and their analysis correspond to a case where the appropriate pattern of uncertainties is not as completely clear cut as with the dice. Nevertheless, the way the IPCC chose to present the result does not seem to be justified based on the initial work by Forster and Gregory, and as with many things in IPCC reports, the change has the effect of making things "worse than we thought".

Jul 6, 2011 at 9:52 AM | Unregistered CommenterJeremy Harvey

Jeremy, great summary. Another key point made by Nic is that Forster and Gregory's study was the only one in AR4 WG1 to show a probability density function (PDF) for sensitivity (S) that was not based on climate models of any kind, such as CGMs, but from direct measurements.

The good thing that can be said about this WG1 is that they didn't totally ignore real-world data. The real-world data though gave a PDF that looked far less threatening than the ones generated by models.

That's the background for the adjustment. It's incredibly important background. There is no way such a major channge should have been made to the shape of the PDF graph of Forster & Gregory without first going through peer review and publishing of the rationale.

Jul 6, 2011 at 10:11 AM | Unregistered CommenterRichard Drake

As a retired teacher, I understand very well that altering any piece of another party or parties' academic work that is put forward for any reason whatsoever is absolutely beyond the pale and would normally attract heavy legal/professional sanctions. To alter a statistical process in an academic peer reviewed paper to give a significantly different result from the original is way beyond dubious practice. The problem, as I see it, is the question of which individual or statutory group is (or should be) responsible for policing behaviour at this level.

Jul 6, 2011 at 10:41 AM | Unregistered CommenterAlexander K

Thanks for that. This dumbo struggles to wrap his mind round statistics, I'm afraid.
I understand that there is always likely to be a divergence of views between one research team and another in situations like this but I go along with Richard Drake and Alexander that if I do the work and publish the results I expect those results to be used as I intended them and not "tweaked" to fit someone else's ideas.
Especially when those ideas are not based on empirical evidence and always appear to be aimed at making things -- to use the old cliché -- "worse than previously thought".
Surely incorporating a range of possibilities is going to make the IPCC output more acceptable especially where part of the input to the discussion is based on observations rather than models. As it is it is so easy to dismiss a lot of it out of hand simply because it takes such a cavalier approach to anything that downplays the catastrophic element.
If at the end of the day the warm-mongers turn out to be right and we have done nothing to avoid the catastrophe (though I dont't believe they are and I can't see what we can realistically do anyway) they can blame the IPCC (which is to say themselves) for continually shooting themselves in the foot in this way.
It simply makes no sense.

Jul 6, 2011 at 11:26 AM | Unregistered CommenterMike Jackson

Jeremy Harvey -

Great explanation (that is worthy of being published alongside Doug Keenan's article "How Scientific is Climate Science?" in WSJ - easily found in Google).

I had thought that what the IPCC had done would be considered too esoteric to be explained to the masses and therefore unworthy of much attention but you seem to have achieved the impossible.

Thank you.

Jul 6, 2011 at 11:26 AM | Unregistered Commentermatthu

Phillip Bratby Jul 6, 2011 at 7:01 AM:

Richard Betts @ 12.11AM
"so one would assume that they were happy with what the chapter 9 lead authors did."

I would assume nothing. I would want to see the evidence that they were happy. In light of what Steve McIntyre has said, they probably had no say in the final version. Most comments seem to be either ignored, rejected or reinterpreted by the lead authors.

Nic Lewis indicated that he has alerted Forster and Gregory to his post (and my guess is that he is unlikely to hear from them!). Knowing what we know about the IPCC (regardless of how "happy" F & G might - or might not - be), seems to me that Gregory had at least 32 good reasons** to throw the conclusions of Forster and Gregory (2006) under the proverbial (graphical?!) bus.

If my work was referenced in such a "prestigious" report, I think I'd want to see how it turned out - wouldn't you?! Silence, after all, is acquiescence - and F & G have been silent for 4 years.

** See: Is the IPCC conflicted? Here is one of the ways

Jul 6, 2011 at 11:32 AM | Unregistered Commenterhro001

Bloke in the Melbourne press (Col. of Blackburn on the Andrew Bolt blog) claiming he has had no money from "Big Tupperware" either...

Jul 6, 2011 at 11:50 AM | Unregistered CommenterRoger Carr

Hilary, thanks for the data about Forster & Gregory's contributions to IPCC AR4 WG1 in your post. It doesn't mean Nic won't hear from them at all. What is does mean is that if they were to make clear their unhappiness with the adjustment in Ch 9 Fig 9.20 it would be no small beer.

Jul 6, 2011 at 11:54 AM | Unregistered CommenterRichard Drake

The problem is just this, and nothing less:

a.) In setting boundary conditions for
the results of scientific investigations,

b.) Politicians have inadvertently made
honest science a defiance of government.

What a heck of a mess!

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo

Jul 6, 2011 at 12:19 PM | Unregistered CommenterOliver K. Manuel

They may have had no choice but to acquiesce. That doesn't mean they are happy.

Jul 6, 2011 at 12:19 PM | Unregistered CommenterPhillip Bratby

Thanks for the explanation. Like Mike, I struggle to get my head around complex statistical stuff but your clear explanation has burned off the fog in my brain. .

Jul 6, 2011 at 1:00 PM | Unregistered CommenterAlexander K

Many thanks to Jeremy Harvey, and to James, for their excellent summaries of my article. That is very helpful - I tend to concentrate on getting things exactly correct rather than on easy to understand!

I wrote in a comment at Climate Etc that Piers Forster and Jonathan Gregory were Contributing authors for chapter 9 of AR4:WG1 and, presumably, accepted (at least tacitly) the IPCC’s treatment of their results. I have no real doubt that they both were aware of and accepted that treatment. They may have seen the plain statement in the IPCC report that their results had been modified to a uniform prior in sensitivity as making showing them on that basis acceptable. Or they may have (mistakenly) have been persuaded by David Frame and his colleagues - advocates of the uniform prior in sensitivity basis - that that basis was appropriate and that the original basis in their study was unrealistic.

Jul 6, 2011 at 2:01 PM | Unregistered CommenterNic Lewis

Would some kind soul add a footnote to the good Jeremy Harvey's exposition above?

The footnote would consider these "confidence interval" thingies. One reads a lot about them, and one wonders who arrives at them, and how. Do they in fact have any meaning.

Another consideration: IPCC papers love to quote confidence levels of 95%. Yet I have read that this level is not especially significant, and a knowledgeable comment would be appreciated, possibly by others than me.

Jul 6, 2011 at 2:08 PM | Unregistered CommenterJeff Wood

"The IPCC ignored the methods in the paper and used their own methods"

"There is no support for this claim in the peer reviewed literature. The paper they cite (Forster and Gregory) does not support this conclusion."
Jul 6, 2011 at 9:14 AM | TerryS

I come back to my earlier question about who has been involved in the changes and would point out that the IPCC is a U.N. non entity of fund raising bureaucrats.

Having now moved onto the original papers comments here

it can be seen in the comments that that there is an AGW bias but thanks to Jeremy etc for helping me save a lot of research!.

Jul 6, 2011 at 2:58 PM | Unregistered CommenterPete H

Sea level has it’s own curve stretching issue. One of the Hockey Stick team and organizers named Rahmstrof used a very odd mathematical alternative curve shape instead of just fitting a curve to his data. The difference is shown here:


Another bizarre oddity in the paper is the fitting of a straight line to scatter plot data that does not merit a linear fit. Then he extrapolates far into the future, based on it, as shown here:


These odd manipulations (along with added “corrections” to *actual* sea level based on water reservoirs on land, while ignoring ground water pumping) resulted in a sea level curve that shows a recent upswing:


Tom Moriarty’s blog at has several recent entries on this fiasco.

In other news, basic sea level data is not on the pro-AGW side at all:


Jul 6, 2011 at 3:01 PM | Unregistered CommenterNikFromNYC

Thanks to S.M. over at Climate Audit for a much clearer link to the papers comments!

Jul 6, 2011 at 3:04 PM | Unregistered CommenterPete H

The irony is that today's Guardian is claiming that the IPCC is underestimating climate change. Based on the Rahmstorf nonsense referred to by NikFromNYC above.

Jul 6, 2011 at 4:14 PM | Unregistered CommenterPaulM

The link for Climate Audit by Pete H.

Jul 6, 2011 at 4:20 PM | Unregistered Commentersimpleseekeraftertruth

Why wont BBD, dana and the consensus-makers comment on this?

The IPCC is supposed to assess science, not do science.

What is done here is not an assessment, but an act of creation. The outcome of such 'creation', is then dubbed an assessment, which is supposedly the expert appraisal of the existing literature.

If the IPCC cannot be taken for its word, of what it does, how can one believe what it says?

When I read the IPCC, I want to know what Gregory and Foster wrote, in their peer-reviewed paper, and what the IPCC authors assessed it to mean, not what the IPCC authors decided to change it to mean.

Why is this so difficult? And why is this a recurring problem in the environmental sciences, and climate science?

Jul 6, 2011 at 4:27 PM | Unregistered CommenterShub

From that Guardian article (thanks PaulM):

... a group of young Australian climate scientists released an expletive-filled music video earlier this year. It was an angry rap aimed at those who question climate science while holding no qualifications in the field. They used the rather unscientific word "motherfucker" and poured scorn on "bitches" opposing a carbon tax.

Hearteningly, there may be more of this to come. Paul Nurse, the new president of the Royal Society, has said he would be happy to see scientists getting fully engaged with politics and involved with activism.


Compare this blatant advocacy of anger with the sweet reasonableness of Nic Lewis from the moment his post went up on Climate Etc - the discovery of which a few minutes later ranks as one of the three most exciting moments on the climate blogosphere for me.

Fortunately it's not possible to see the future but this contrast in 'styles' is going to make for an interesting one. Never have the foundations of IPCC dogma and the dodgy presentation thought to be needed to protect them been questioned with such precision. For exactly that reason I can't see the anger going away any time soon either.

Jul 6, 2011 at 4:33 PM | Unregistered CommenterRichard Drake

Shub: Well said. I agree whole heartedly with you.

Jul 6, 2011 at 4:51 PM | Unregistered CommenterPhillip Bratby

Thanks Richard Drake for spotting this in the Guardian article:

“... a group of young Australian climate scientists released an expletive-filled .. angry rap aimed at those who question climate science.. Hearteningly, there may be more of this to come. Paul Nurse .. has said he would be happy to see scientists getting .. involved with activism..”

It’s worse than we thought. Even the subtitles are wrong, with more errors than an IPCC graph. In the interest of accuracy, here are the lyrics:

YO! We’re climate scientists, And there’s no denying this
Climate Change is REAL
Who’s a climate scientist? I’m a climate scientist
Not a cleo finalist? No, a climate scientist
Droppin facts all over this wax
While business be crying about a carbon tax
Climate change is caused by people
Earth unlike Alien has no sequel
We gotta move fast or we’ll be forsaken
Cos we were too busy suckin things in Copenhagen
Hey! it’s hot in here
32% more carbon in the atmosphere
oee oee oee, ice ice ice
Raisin’ sea levels twice by twice
We’re scientists - what we speak is True
Unlike Andrew Bolt our work is Peer Reviewed .... ooohhh
Who’s a climate scientist? I’m a climate scientist
An Anglican revivalist? No, a climate scientist
Feedback, like climate change on crack
permafrost subtracts - Feedback
Methane release is wack - Feedback
Write a letter then burn it? - Feed back
Denialists deny this in your dreams
Cos climate change means greater extremes
Heat will be the norm
Heatwaves bigger than a storm
The greenhouse effect is just a theory, sucker
Yeah so is gravity, run away mother floater ooohhh!
Who’s a climate scientist? I’m a climate scientist
A penny farthing cyclist? No, a climate scientist
A Fox News journalist? Nooh!!! A Paleontologist? Nooh!!!
A clean coal lobbyist? Nooh!!! A cashed up alarmist?Nooh!!!
A climate study scientist!

Jul 6, 2011 at 5:37 PM | Unregistered Commentergeoffchambers

I forget whether it was WUWT or Steve McM who linked through to this 'great' video a few weeks ago. Those who know me will tell you I'm not a great fan of this kind of music... so maybe I'm not the best judge. But frankly...

Jul 6, 2011 at 5:50 PM | Unregistered CommenterJeremy Harvey

From over at Climate Audit

Steve McIntyre
Posted Jul 5, 2011 at 10:53 PM

"Hegerl and Zweiers were the CLAs. They were also coauthors of hegerl et al, cited in the caption of Figure 9.20 for the methodology. The alteration to Fig 9.20 style would have been done by or under the supervision of hegerl and Zwiers. They were also judge and jury in rejecting Annan’s criticism of uniform priors."

Thanks as usual to S.M. for clarification.

Jul 6, 2011 at 5:54 PM | Unregistered CommenterPete H

'motherfloater'? Is that some kind of safety device for maternal matelots, geoffchambers? I could have sworn those degenerate singers said something else.

Jul 6, 2011 at 5:56 PM | Unregistered CommenterJohn Shade

Geoff & Jeremy, it was the transition from cod climate rap through "Heartingly ..." to "Paul Nurse [is encouraging this kind of thing]" that really got me.

Jul 6, 2011 at 5:58 PM | Unregistered CommenterRichard Drake

John Shade
The Guardian quotes the vulgar version, and links to the “cleaned up” version. And the Australian climate scientists can’t even quote themselves correctly in the subtitles. A bit like Forster and Gregory and the IPCC really...
Peter Gosselin has a rather good German sceptic rap at

Jul 6, 2011 at 6:21 PM | Unregistered Commentergeoffchambers


Why wont BBD, dana and the consensus-makers comment on this?

As I recall, last week I was carrying out an extended and more-or-less solo defence of the argument for low climate sensitivity. With a kind of anti-help from you.

Jul 6, 2011 at 6:23 PM | Unregistered CommenterBBD

'things'= 'dicks' in the non bowdlerised version of the rap. Was the new version produced by embarassed 'climate scientists'? Is this a lyrical version of data modification? Who can you trust these days? It was a gross video - one that suggests a peculiar, somewhat demented perspective on those who have refused to join in the panic being enjoyed, and exploited, by the singers. And it is a bit of an unwelcome, tasteless diversion on this otherwise informative thread - although it does provide a telling, informative contrast, as RD pointed out at 4:33PM.

Jul 6, 2011 at 6:25 PM | Unregistered CommenterJohn Shade

@Jul 6, 2011 at 12:18 AM | James

I think your rephrasing is most succinct. Bravo!

Jul 6, 2011 at 6:30 PM | Unregistered Commenterjorgekafkazar

Is anyone keeping a scorecard or register of instances where scientific papers are modified after the event or source data is adjusted without notification or reasonable cause? If not, I believe that someone with the competence and outlet (blog/website) who did so would be doing everyone else a very great service indeed.

IIRC this is not the first time a paper has been altered. I believe that recently data on sea levels has been adjusted. There have, I believe, been at least one if not two occasions where sharp eyes have spotted changes in historical temperature data sets without notification. I would cite the great dying of thermometers c1990 worthy of inclusion in such a register because of the impact it seems to have had - a real case of man made warming if ever there was one.

I suspect that such a register would shock.

Jul 6, 2011 at 7:08 PM | Unregistered Commenteroldtimer

As for what I think about the apparent misrepresentation of F&G, it is this:

- This is not evidence against AGW

- This is strongly suggestive of IPCC WG1 bias in emphasising the likelyhood of the most severe outcomes from AGW

- It's not as bad as the Mannean Hockey Stick in AR3

- It's the same general sort of thing though

- Breaking the handle of the Hockey Stick doesn't 'refute AGW'

- This doesn't 'refute AGW'

- Both the above suggest zeal bordering on desperation within the IPCC to get the point across. The old 'Schneider balance' between honesty and effectiveness again.

A few words about Richard Betts:

Here is James Lovelock in an email to Stewart Brand, quoted by the latter on p305 of his book Whole Earth Discipline:

Apart from a few friends like Richard Betts, my name is now mud in climate science circles for having dared to consort with sceptics. Amazing how tribal scientists are.

Let's bear that in mind when he visits next.

Jul 6, 2011 at 7:12 PM | Unregistered CommenterBBD

Didn't Paul Nurse get a Nobel Prize for a popular video - or was that a discredited US politician?

Jul 6, 2011 at 7:14 PM | Unregistered CommenterZT

I should maybe cross-post here a comment that I have recently made at Climate Etc:

Gabi Hegerl, joint coordinating lead author of AR4:WG1 Chapter 9, has asked that it be mentioned on this blog that the authors of Forster and Gregory were part of the author team and not unhappy about the presentation of their result (in Figure 9.20). I hereby do so. That firms up my tentative earlier comment that F&G were Contributing authors for chapter 9 of AR4:WG1 and, presumably, accepted (at least tacitly) the IPCC’s treatment of their results.

Piers Forster has also confirmed that when their paper was published, he tried to invert the results (convert them from Y to S) and got a range of sensitivity much like Figure 3 in this post. However, he remembers being persuaded by the Oxford group (Frame, Allen, Stainforth, etc, I assume) and other statisticians that by doing this simple inversion F&G were inadvertently assuming a very skewed and unrealistic prior themselves.

Of course, whether or not the authors of a paper agree with presenting its results on a different, inconsistent basis in no way shows that doing so was valid, nor that there was anything wrong with the basis on which they were originally presented. I am not sure that Piers Forster realised that doing anything other than a simple inversion would produce a PDF for S that implied the results for Y presented in their paper were wrong. Perhaps David Frame told him that no such implication arose. Certainly, Frame doesn’t seem to have been very concerned about the inconsistencies between the various approaches he advocated. As climate scientist James Annan wrote, commenting on the approaches advocated in Frame 05: “Basically, you have thrown away the standard axioms and interpretation of Bayesian probability, and you have not explained what you have put in their place.”

Jul 6, 2011 at 7:31 PM | Unregistered CommenterNic Lewis

As it happens his next visit was 3 minutes later! Fascinating quote from James Lovelock. Thanks.

Jul 6, 2011 at 7:43 PM | Unregistered CommenterRichard Drake

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