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Marotzke's circularity

A few days ago I noted a new paper by Marotzke and Forster which claimed to show that the recent divergence of model predictions and observations was all down to natural variability. The paper was getting considerable hype from Marotzke's employers, the Max Planck Institute:

Sceptics who still doubt anthropogenic climate change have now been stripped of one of their last-ditch arguments...the gap between the calculated and measured warming is not due to systematic errors of the models, as the sceptics had suspected, but because there are always random fluctuations in the Earth's climate.

Marotzke was also quoted as saying: "The claim that climate models systematically overestimate global warming caused by rising greenhouse gas concentrations is wrong" and he went on to get quite a lot of media coverage, including the Mail, the Sydney Morning Herald, Deutsche Welle, and the Washington Post

Based on media coverage of the paper's contents, I expressed considerable concern over what the authors had apparently done. It seems, however, that my criticisms at the time were understated. It is in fact "worse than we thought".

These uncomfortable facts are revealed in Nic Lewis's analysis of the paper, which has recently appeared at Climate Audit. Nic, assisted by Gordon Hughes and Roman Mureika, has identified some glaring statistical errors in the paper, but these turn out to be just the tip of the iceberg, as I shall now try to explain.

Marotzke's method involved seeing how far inter-model differences in the temperature trends in a group of climate model runs could be explained by differences between models in changes in forcing and two "structural elements":  the climate feedback parameter and the ocean heat uptake efficiency. However, the time series for the forcing changes and the estimates of the structural elements came from another paper, by Forster et al. (and hence Forster's appearance as a co-author, or at least so one assumes).

Unfortunately, Marotzke seems not to have understood that Forster had calculated the forcing time series using an equation that expressed them as a function of model temperature. This meant that when the figures were plugged back into Marotzke's regression model he effectively had temperature on both sides of the equation: he was regressing temperature on a function of temperature and the logic was circular!

But in fact, even if the work could be redone without the circularity, Nic reckons the general approach is still "doomed". Readers will have gathered from my introduction that the whole study revolves around model output. It's completely divorced from the real world, apart from a brief and somewhat tenuous claim that "the simulated multimodel ensemble spread accurately characterizes internal variability". But unfortunately, even in model-world, the values Marotzke used for the ocean heat uptake efficiency vary wildly from those estimated from the model runs he uses. For example, in some models a degree of surface temperature rise over 1951–2012 produced twice as much inflow of heat into the oceans as that implied by the model ocean heat uptake efficiency value used by Marotzke. In others it produces only half as much. The same problem may well also arise with climate feedback parameter, but Nic tells me the circularity issue means one can't tell. With the diagnostic data being so poor, you are never going to be able to explain the causes of variation in historical temperature changes between models.

Amusingly, Marotzke declared on the paper's release that "The difference in sensitivity explains nothing really...I only believed that after I had very carefully scrutinised the data on which our graphs are based". It appears that his scrutiny was not careful enough.

I think it's fair to say that this is the last we will be hearing of Marotzke and Forster 2015.

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Reader Comments (63)

Unfortunately, as we know, the damage has been done, the meme has entered the alarmstream... the pause is explained.

Feb 5, 2015 at 3:51 PM | Unregistered CommenterTheBigYinJames

[Snip - venting]

Feb 5, 2015 at 3:53 PM | Registered CommenterSalopian

I think it's fair to say that this is the last we will be hearing of Marotzke and Forster 2015.

Sorry, but you are mistaken. It is irrelevant if a paper is good, bad or simply junk. The only thing that matters is whether it is "on-message". If it is on-message then it will be regurgitated again and again as proof no matter what. If it isn't on-message then it is irrelevant because whoever wrote once filled up with petrol or some PR consultant somewhere said it is wrong.

Feb 5, 2015 at 4:03 PM | Unregistered CommenterTerryS

I do hope this IS NOT the last we from Marotzke and Forster, or their paper. They have obviously been paid to find evidence, to support a theory.

In the absence of real world evidence, they have had to rely on evidence fabricated within climate models.

There is space within climate science for integrity, but no one will hear you scream

Feb 5, 2015 at 4:28 PM | Unregistered CommenterGolf Charlie

It provides further proof of Lindzen's statement to the House of Commons Energy and Climate Change Committee

"I've asked very frequently at universities: 'Of the brightest people you know, how many people were studying climate?' And the answer is usually 'No one.'" "You look at the credentials of some of these people and you realise that the world doesn't have that many experts, that many 'leading climate scientists'".

Was Lindzen suggesting, asked Tim Yeo at this point, that scientists in the field of climate were academically inferior.

"Oh yeah," said Lindzen. "I don't think there's any question that the brightest minds went into physics, math, chemistry…"

Feb 5, 2015 at 4:53 PM | Registered CommenterPhillip Bratby

If Michael Mann can award himself a Nobel Prize, should the "Lance Armstrong Award for outstanding excellence in integrity" now be created?

To ensure that credit is correctly attributed, this award would be for instigating scientists, the publishing editor and journal, and not forgetting the anonymous peer reviewers, whose lack of work so easily goes unnoticed.

Feb 5, 2015 at 4:54 PM | Unregistered CommenterGolf Charlie

One interesting thing I have noticed with warmists is that many might claim to be scientific, but blatantly display unscientific thinking. I am still involved with a discussion on Richard Telford’s site (thanks, Latimer Alder – someday, I’ll get these wax dolls to work, then you’ll be sorry!). What I find most, erm, alarming is that few of the respondents appear to even read what I have written, accusing me of making the most outrageous claims, when I have not even hinted at what they say. It would appear that they have a mental model of what I should be saying in their minds, and that is what they reply to. This could be an explanation for Marotzke and co’s thinking; if this is now common of modern scientific minds, then we do truly have no hope.

Feb 5, 2015 at 5:10 PM | Registered CommenterRadical Rodent

Gordon Hughes had some pithy comments about the Marotzke and Forster paper:

The statistical methods used in the paper are so bad as to merit use in a class on how not to do applied statistics.

All this paper demonstrates is that climate scientists should take some basic courses in statistics and Nature should get some competent referees.

The paper is methodologically unsound and provides spurious results. No useful, valid inferences can be drawn from it. I believe that the authors should withdraw the paper.


Feb 5, 2015 at 5:12 PM | Registered CommenterPhillip Bratby

Philip: You read my mind (easily done) when you suggested the paper should be withdrawn.

My thoughts were about:how does a paper get withdrawn once the referees/peers have accepted it? (And what kind of Peer Review was carried out if the paper can be taken apart so easily???) I suppose, that in their anonymity, it's no skin off their noses, but if they are known they will need to protect their reputations against a such a withdrawal.

Feb 5, 2015 at 5:24 PM | Registered CommenterHarry Passfield

Very well done to all concerned, except of course the authors of this awful paper and anyone else who facilitated this latest attempt at policy-based evidence-making.

Feb 5, 2015 at 5:26 PM | Registered CommenterJohn Shade

Nature AGAIN?????

Does this "respected" Journal now have the most abysmal record for letting garbage masquerading as science through its "gold standard peer review process"?

Feb 5, 2015 at 5:28 PM | Unregistered CommenterGeckko

One thought.

Is the propensity of "mainstream" climate science to apparently avoid peer review from unclean types, like Nic Lewis, Steve Mcintyre etc. their greatest failing?

Feb 5, 2015 at 5:30 PM | Unregistered CommenterGeckko

The paper's conclusion contains an absurd logical flaw that Nature's editors and reviewers should have caught. The paper's purpose was to examine the (self proclaimed) two most important emergent model properties, alpha and kappa, respectively climate feedback (1/ECS) and ocean heat uptake. It concluded the two most important emergent structural properties have no statistical impact on model performance. Ridiculous. Proof that the methods used to reach such an absurd conclusion must be flawed. Nic Lewis showed how and why. The paper has to be retracted. Lets hope that gets MSM coverage.

Feb 5, 2015 at 5:33 PM | Unregistered CommenterRud Istvan

[Snip - raise the tone please]

Feb 5, 2015 at 5:33 PM | Unregistered Commentertom0mason

The problem the UKMO has is that the warming of the oceans is nothing to do with ‘back radiation’, a Radiant Emittance..Instead it’s roughly constant SW thermalisation plus the decrease of upwelling cold water which started its journey from Antarctica 800 years ago, when the Mediaeval Warm Period ended and Antarctic Ice started to increase.

So, to predict future air temperature, one must have data about ice and snow formation from the year 1200! Climate Alchemists really must learn about all coupled factors, including the thermohaline circulation.

Feb 5, 2015 at 5:36 PM | Unregistered CommenterNCC 1701E

As Nic and Rud point out, there is a huge red flashing light in the abstract and conclusions of Marotzke and Forster that should have indicated to the reviewers and the authors themselves that there was something seriously wrong with what they were doing.

Abstract: For either trend length, spread in simulated climate feedback leaves no traceable imprint on GMST trends

Conclusions: we find no substantive physical or statistical connection between simulated climate feedback and simulated GMST trends over the hiatus or any other period

The feedback parameter (essentially the inverse of the climate sensitivity) varies by a factor of 3, from 0.6 to 1.8. Yet according to their method, it has virtually no influence on the warming trend!

Feb 5, 2015 at 5:39 PM | Registered CommenterPaul Matthews

So sceptics have never said that there are random variations?

Mike Haseler (aka Scottish Sceptic) 2009 submission to House of Commons Science and technology committee inquiry to Climategate:

The Null Hypothesis (Natural Variation) is Consistent with Global Temperatures

Unless the warming in these decades far exceeded the normal inter-decadal change in global temperatures, the mere fact of three decades of warming is in itself entirely consistent with the null hypothesis of natural variation.

This means there are natural increases & decreases in temperature over periods of up to a century which are larger than the inter-decadal or year to year variation. So there are natural long-term fluctuations in the climate which may easily be misinterpreted as man-made forcing on the climate.

To highlight the similarity of the global temperature to natural noise, a section of 1/f noise (pink noise) is shown with lines in blue modelling the yearly average and red the decadal average.

May I return the complement and use his form of argument:

[Snip - raise the tone please]

Feb 5, 2015 at 5:56 PM | Registered CommenterMikeHaseler

The paper has done it's job. It is in print. This is post-normal science. A paper's job is to stand there and be pointed at: "Look! Lots of papers! It's sciency!"

Feb 5, 2015 at 5:59 PM | Unregistered CommenterStuck-Record

I think it's fair to say that this is the last we will be hearing of Marotzke and Forster 2015.

I think it's fair to say that we can continue to expect more papers of a similar calibre in the run up to our next "last chance" climate meeting in Paris later this year. Many of them will not give a damn about careful science but will be playing to their supporters in the gallery.

Feb 5, 2015 at 6:12 PM | Unregistered Commentermichael hart

The conclusion that the pause has been explained by natural variability begs the obvious question - if the pause is explained, why do they think the rise in temperature wasn't also explained by natural variability to begin with?

Feb 5, 2015 at 6:29 PM | Unregistered CommenterTom O

just for the record (the record is not well kept imho) :

the warmish sceantific establishment was enthusiastically jumping on this new explanation for the lost heat, but it is like
the 3 dozens explanations before a dud.

so much for all that settled science and grandstanding by the wammish

what does paul nurse think??

Feb 5, 2015 at 6:37 PM | Unregistered Commentervenusnotwarmerduetoco2

'I think it's fair to say that this is the last we will be hearing of Marotzke and Forster 2015.

I think you may be wrong , time and again we seen that no matter how rotten the work , how worthless the 'data ' and how poor the methodology. Once something has entered the dogma of 'the cause' it becomes the unquestionable word of god.
Remember what matters is the 'impact' not the honest of 'research '

Feb 5, 2015 at 6:50 PM | Unregistered CommenterKNR

Tom O, this flawed paper did not assert natural variability. That would open the logical can of worms you aptly note. (Also covered in essay Unsettling Science in my new ebook).
It was a response to the sceptical arguement (not just in blogs, see Nic Lewis and Judith Curry's most recent paper) that observations (like the pause) show 'observed' sensitivity is much lower (~1.7) than CMIP5 models (~3.2). Sensitivity is a key policy driver with respect to both urgency and end outcomes. It attempted to show that model sensitivity does not affect model temperature output, so that in effect the pause was 'just luck' and the model outcomes could still be relied upon (at COP21). Words to that general effect are actually in some of the paper's PR.

Feb 5, 2015 at 7:40 PM | Unregistered CommenterRud Istvan

Yet more policy based evidence making. This has all the hallmarks of a hit-job on model failures, just as they do similar jobs on sensitivity, temperatures and anything else where observations start to ruin the theory. Notice how magically natural variation is now in vogue, albeit this time it's supposedly working in their favour. W*****s too a man.

Feb 5, 2015 at 7:48 PM | Unregistered Commentercheshirered

It's endearing how many papers are supposed to be the one that "finally silences skeptics".

Feb 5, 2015 at 7:48 PM | Unregistered CommenterBrute

Let me repeat what I saoid about Marotzke on February 1st:

"First, there are several inter-related problems here. To me "tuning" a climate model is equivalent to falsification of science. Their untuned models have never correctly forecast any future climate, starting with Hansen's "business as usual" model in 1988. He attempted to forecast coming global temperature through 2019. We have seen most of these years go by and all of his predictions have been wrong. Some thought that using supercomputers instead of an IBM mainframe that Hansen used would improve the accuracy but this did not happen. The output from supercomputers running one million line code was no better than Hansen's work was in 1988. And once the cessation of warming dubbed a "hiatus" appeared the computers got lost entirely. They have had 27 years since Hansen to get their house in order and this has not happened. It is time to recognize that computer prediction of future climate cannot be done and close the modeling operation entirely. Now lets take up the Marotzke and Foster claims. Ever since the existence of the hiatus became known there have been numerous attempts to explain it away. Their claim is one that borders on the absurd. These denials were often peer reviewed scientific articles. Anthony Watts kept track of them but when their number went over fifty he gave it up. To me the most fascinating ones were those that were looking for the lost heat in the ocean bottom. I find it hard to explain how such nonsense got past the peer review process. But then again, my personal expereience with them should explain it in part. When Al Gore claimed that a twenty foot sea rise was heading for us I found an article in Science proving that sea rise for the previous 80 years had been 2.46 millimeters per year. That was under ten inches, not twenty feet per century, and I quickly submitted an article about it to Science and to Nature, in succession. In both cases it was returned without bothering with such niceties as a peer review, and Al Gore got a Nobel Prize for his nonsense. The current attempt to deny the existence of the hiatus is a new twist towards unreality by the core climate science establishment. You may not know it, but this is not the first but the second time that these guys have suppressed or attempted to suppress the existence of a hiatus. The first time was in the eighties and nineties and it was successful. GISS. NCDC, and HadCRUT cooperated to create a fake warming for that temperature stretch. It amounted to a fake rise of 0.1 degrees from 1979 to 1997. It did not stop there but continued into the next century. Proof of collaboration is identical computer footprints in all three data-sets. The fake warming and computer footprints are not present in satellite temperature curves. I discovered this while writing my book "What Warming?" (Amazon carries it) and even put a warming about it into the preface. But nothing happened. They are continuing with that fake upslope on top of the current hiatus which is so ridiculous now that their 2010 El Nino is higher than the super El Nino of 1998. That is impossible. And from this it was only a small step for them to declare 2014 the warmest year ever. During the eighties and the nineties ENSO was active and created five El Nino peaks during that period, with La Nina valleys in between. This gave the fakers cover because the existence of a wave train can confuse people trying to determine global mean temperature. Figure 15 in my book shows how it is done. First, use a wide marker to cover the fuzz around the trend line. This will give you the outline of the wave train. Next, put a dot at a point halfway cbetween the El Nino peak and the bottom of the neighboring La Nina valley. These dots mark the location of the global mean temperature at that date. I did this for the entire wave train and the dots lined up in a horizontal straight line, proving absence of warming for 18 years. These 18 years should be added to the 18 years of the current hiatus, giving a total of 36 years of no-warming since 1988. This takes up three quarters of the time that has lapsed since the IPCC was formally established. Any temperature changes that have taken place have to fit within the twelve year time slot not taken up by any hiatus.

Feb 1, 2015 at 3:27 AM | Arno Arrak"

Feb 5, 2015 at 7:50 PM | Registered Commenterarno-arrak

97% of climate scientists are in need of some basic courses in statistics!

Especially the pretend Nobel Laureates!

Feb 5, 2015 at 8:01 PM | Unregistered CommenterCharmingQuark

The Max von Planck Institute, where no scientists, or their papers are considered too thick, or short, provided they are on message.

Next month, they will be reviewing absorbancy of 3-ply toilet tissue, following extensive tests wiping their elbows.

Feb 5, 2015 at 8:13 PM | Unregistered CommenterGolf Charlie

"there are always random fluctuations in the Earth's climate."

I thought that was our line? Warmists tend to bristle when you suggest that sort of thing!

Feb 5, 2015 at 8:41 PM | Registered Commenterjamesp

How does one get a paper withdrawn.

Feb 5, 2015 at 8:46 PM | Unregistered CommenterStephen Richards

[Snip - raise the tone please]

Feb 5, 2015 at 8:51 PM | Registered CommenterMikeHaseler

"last-ditch arguments"

Not quite.


Feb 5, 2015 at 9:04 PM | Unregistered CommenterBad Andrew

Stephen Richards Mike Hasseler How does one get a paper withdrawn?

Depress the lever marked "Flush"

Feb 5, 2015 at 9:13 PM | Unregistered CommenterGolf Charlie

You can tell they are third-rate from their seemingly oblivious use of immoderate language in supposedly formal writing.

Feb 5, 2015 at 9:27 PM | Unregistered CommenterJake Haye

Lindzen's quoted comment about the brightest not going into climate science --I read the other day that Mann took 9 years to get his PhD. There was no reference to back up the statement and there could be valid reasons for the length of time but then again, there could be an obvious reason. Maybe others have better information.

Feb 5, 2015 at 10:01 PM | Unregistered CommenterRoss

Any assessment that includes a significant effect from CO2 is wrong.

Anyone with access to recorded CO2 and temperature measurement data, who was paying attention in first year calculus, and can extrapolate the math to the physical world, can falsify the statement that CO2 causes significant warming.

See how and discover the two factors that do cause climate change (95% correlation since before 1900) at . The two factors which explain the last 300+ years of climate change are also identified in a peer reviewed paper published in Energy and Environment, vol. 25, No. 8, 1455-1471.

Feb 5, 2015 at 10:20 PM | Unregistered Commenterdan pangburn

Never assume Bish. Have a look at Piers Forster's twitter feed. He thinks of the paper as 'ours' i.e he is a happy co-author with Marotzke. There's nothing accidental or limited about his involvement, I reckon. Poor fellow. And he's been tweeting with Robert Way - the bloke who Nic Lewis also showed up for not apparently knowing his times by from his divides by.

I don't expect Forster or Way to ever invite Nic Lewis round for beers, although they probably should just swallow their pride and try learning from him.

Feb 5, 2015 at 11:11 PM | Unregistered CommenterWB

One more for the press cuttings: business as usual for John Timmer and Ars Technica.

I think it's fair to say that this is the last we will be hearing of Marotzke and Forster 2015.

Well, if nothing else there's another winter offensive through the <cite>Nature</cite> comment process to look forward to, I assume...

Feb 5, 2015 at 11:45 PM | Unregistered Commenteranonym


public corporal punishments on the market square.

That is the only thing that will silence them.

Feb 6, 2015 at 12:16 AM | Unregistered CommenterMars Shmallow

@Bish: Respectfully, it is your blog but, if you think planck/plank comparisons are 'venting' and deserve snipping, don't you think your 'sheep in Wales' headline was OTT, given that myself and another commenter pointed out that it was based on an incorrect Reuters press release, and how about snipping some of the anti-Welsh comments on that thread?

Feb 6, 2015 at 1:19 AM | Registered CommenterSalopian

Ross: Mann took 9 years (probably) because he started out in Physics and failed to matriculate - hence the Master's degree in Physics, from a school that does not offer one.

I used to wonder "don't these guys know their work is going to be scrutinized by every skeptic on the planet?" Then I realized that yes, they do know this, but are suo awful they have no idea how bad their work is. It would be sad if there were not so many repercussions the rest of us must live with.


Feb 6, 2015 at 2:23 AM | Unregistered CommenterMark T

"........- hence the Master's degree in Physics, from a school that does not offer one."

This appears to not be the case.

Feb 6, 2015 at 3:39 AM | Unregistered CommenterS. Geiger

Bish is 97% certain that bogus papers don't grow legs.
- The anti confirmation bias habit is so strong among alarmists - that they themselves immediately deeply analysed the paper and set about replicating it. They didn't just jump on Twitter and start retweeting like crazy. /sarc

Hey Tonto ! Sounds like wagons circling in the distance

Talking of alarmist tweeting ..a large proportion of the tweets mentioning Marotzke come from ATTP (University of Edinburgh)
- The Paradox is Willie Soon is persecuted for using private money for his work - and said somehow giving PR to Climate skeptics. (despite people finding no actual fault with his work)
- Has anyone totted up how much of our time/ money Scientist Activists like ATTP use up doing extensive Climate Alarmism PR when they should be doing real work ?
..surely that is stealing from the taxpayer and a form of corruption.

Feb 6, 2015 at 4:23 AM | Registered Commenterstewgreen

Anyone who has written a scientific paper and submitted it to a journal knows that the journals ask the author(s) to suggest suitable referees.

Does anyone seriously believe that authors would suggest people who are likely to be highly critical or who will have far more knowledge on key matters (e.g. statisticians when the paper relies on statistic) ?

Feb 6, 2015 at 4:34 AM | Unregistered CommenterJohn McLean

Mars: till the early seventeenth century it was usage in Amsterdam, both for men and women, to be exposed, after their conviction, on the market place before the Town Hall with a notice on their breasts telling what they had done. After one day of exposure they were banned from the city for many years.

Feb 6, 2015 at 4:35 AM | Unregistered CommenterMindert Eiting

The White Stripes wrote a song about climate scientists' statistical skills:
"Black Math"

Don't you think that I'm bound to react now?
My fingers definately turning to black now
Maybe I'll put my love on ice
And teach myself, maybe that'll be nice

My books are sitting at the top of the stack now
The longer words are really breaking my back now
Maybe I'll learn to understand
Drawing a square with a pencil in hand

Mathematically turning the page
Unequivocally showing my age
I'm practically center stage
Undeniably earning your wage
Maybe I'll put my love on ice
And teach myself, maybe that'll be nice

Listen master can I ask you a question
Is it the fingers, or the brain
that you're teaching this lesson?
I cant tell ya how proud I a'm ,
I write about things I dont understand,
Maybe I'll put my love on ice
And teach myself, maybe that'll be nice

Feb 6, 2015 at 7:02 AM | Unregistered CommenterClunking Fist

I meant they retweeted the original Marotzke paper like crazy, and strangely when it comes ton Nic Lewis's deconstruction they will find themselves too busy to do any retweeting.

(what I meant by : "The anti confirmation bias habit is so strong among alarmists - that they themselves immediately deeply analysed the paper and set about replicating it. They didn't just jump on Twitter and start retweeting like crazy. /sarc")

Feb 6, 2015 at 7:20 AM | Registered Commenterstewgreen

Skepteco Blog : "Knock knock, Oi open up Transition Town Eco-Police! You are using far too much fossil fuels!"

Also in the news : "Smack your kids" for not being green enough, says the green hippy Pope

Feb 6, 2015 at 7:44 AM | Registered Commenterstewgreen

Circular in a spiraling, swirling, flushing sort of way,
Regression dilution by Charybditic Bay.

H/t for the first line to commenter hunter @ ClimateAudit.

Feb 6, 2015 at 8:39 AM | Unregistered Commenterkim

You have to wonder at the idiotic illogicality of the press release too!

They can't escape the fact that skeptics were correct to tell them their projected parabolic rise in temperature wouldn't happen because they had underestimated natural variability. The poor model outputs mainly reflect those biased initial assumptions made for the inputs. We have already proven that scepticism is the only rational position and it is the scientivists who are floundering in trying to pretend that isn't so.

Feb 6, 2015 at 8:55 AM | Unregistered CommenterJamesG

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