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Wilson on millennial temperature reconstructions

Last week I attended a lecture given by Rob Wilson at the University of St Andrews. This was a two-hour marathon, a format that is excellent if your lecturer is good enough to carry an audience, as it enables issues to be addressed in much more depth than is the norm. In the event, the time shot by, and if you read on you will see why.

Rob was doing a review of the millennial temperature reconstructions, following the story from the First Assessment Report through to AR5. As readers here know, Rob is no kind of a sceptic (a point he repeated over lunch), but on the northern hemisphere paleo studies his position is not a million miles away from mine. In places our positions are identical, as you will see.

Because of the prominence of Michael Mann's work in the area, some of the lecture was devoted to the Hockey Stick, to the 2008 paper (the "upside down Tiljander" study to the initiated) and to Mann's most recent area of focus, the influence of volcanoes on tree ring growth. Students learned that the Hockey Stick included a whole lot of inappropriate proxies and heard something of the issues with its verification statistics. The wallpapering of the Third Assessment with Mann's magnum opus and John Houghton's claims about unprecedented warmth based on this single study were described as "ridiculous". "Ultimately a flawed study" was the conclusion, with a gory list of problems set out: inappropriate data, infilling of gaps, use of poorly replicated chronologies, flawed PC analysis, data and code withheld until prised from the grasp of the principals. In the paper's defence, it was noted that it was an early attempt at a millennial reconstruction and that it did at least attempt to discern spatial variability, something that had not previously been done.

We also heard about Mann's  minumus parvum opus, The Hockey Stick and the Climate Wars, which Rob, like so many others, had given up on in fairly short order, and then saw an excerpt from Iain Stewart's Climate Wars TV programme. Having seen Mann's paper criticised so forcefully, I assume that Stewart's unquestioning faith in the graph will have left the audience with a pretty low opinion of his abilities.

That was the gentle beginning. When we got onto Mann et al 2008, we learned about the silliness of the screening process, and students were invited to try screening a set of random generated timeseries in the way Mann had gone about this study. Tiljander didn't get a mention, but I guess there are only so many flaws one can take on board, even in a two-hour lecture.

The real fireworks came when Mann's latest papers, which hypothesise that tree ring proxies have large numbers of missing rings after major volcanic eruptions, were described as "a crock of xxxx".

Away from the Mann stuff, this was, as I have suggested a very fair representation of the science of millennial temperature reconstructions, with the overwhelming impression being of a field that is still trying to work out if is possible to constrain the answers to the point where they are useful. The students were undoubtedly hearing the truth, warts and all, about the field they were studying. If only policymakers could hear the truth too.


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Reader Comments (126)

Crock of Shit - as applied to Mann:

More politely known as "a pile of poo", the term "a crock of shit" derives from an ancient Roman custom that coincidentally took place in Roman times. It referred literally to a pot into which people would excrete if they were particularly bored by whichever freelance philosoper happened to be talking rubbish at the time. The Roman empire employed crock-monitors who were each assigned to a philosopher, and it was their job to monitor the pot (or crock). Should the crock become full, it would be presented to the philospher, who was obliged, by law, to announce that it bore a remarkable resemblance to himself, thus proclaiming he was full of crap and was, in fact, talking a crock of shit.
"I am talking a crock of shit", Socrates 429 BC

Oct 21, 2013 at 9:17 AM | Registered CommenterPhillip Bratby

Peer review.

Oct 21, 2013 at 9:33 AM | Unregistered Commenterosseo

Crock monitors. Brilliant thought Phillip Bratby.
We need more crock monitors.

Oct 21, 2013 at 9:39 AM | Unregistered CommenterAndy Scrase

Huge respect to Rob. Presumably the little Mann will be getting his lawyers involved, as usual, before running away to hide, as usual, and blocking any relevant Twitter accounts, as usual.

I still think this gargantuan fr*ud warrants jail time - anybody else concur?

Oct 21, 2013 at 9:40 AM | Registered Commenterflaxdoctor

"Minimus opus" should surely be "parvum opus"?
[Thanks, corrected 10.04am. Today's Moderator]

Oct 21, 2013 at 9:41 AM | Unregistered CommenterJustice4Rinka

See, there are honest and competent people in climate too.

Oct 21, 2013 at 9:45 AM | Unregistered CommenterRichard Tol

@Philip Bratby: surely the ancients would not have wasted such a valuable source of fertiliser. In fact the more a philiosopher provoked these gut reactions, the better for the farming industry on which the city ultimately depended. That is why to this day the Speaker of the House of Commons calls for "ordure, ordure!" and is rarely disappointed.

Oct 21, 2013 at 9:51 AM | Unregistered CommenterSackerson

Sackerson: I think you are talking about mannure.

Oct 21, 2013 at 9:54 AM | Registered CommenterPhillip Bratby

Is the lecture/presentation material available anywhere Bish?

Oct 21, 2013 at 9:57 AM | Unregistered CommenterAdrian

Policy makers would find impossible listening to a two hour presentation, covering any science subject. However, their scientific advisors should find time to experience it: and then put the findings into a ten minute briefing. Having said that, I doubt if the advisors at DECC would risk contaminating their closed minds, by listening to anyone critical of their fixed views.

Oct 21, 2013 at 10:01 AM | Unregistered CommenterPeter Stroud

What's the betting this will not register on, or in, the MSM?

P.S. where can I get a transcript?

Oct 21, 2013 at 10:02 AM | Unregistered CommenterDon Keiller

Will the lecture be posted anywhere? Mann spoke his usual drivel, plus his new histrionics from his book, in Las Vegas, Nevada last July at the annual TAM *"The Amazing Meeting").

This is a group of movement pro-science skeptics who rely on the pronouncements of scientists in the MSM to do their thinking for them. Thus, about climate change, they are insufficiently skeptical. (I lecture to my local group in the Denver, Colorado area about AGW histrionics; a hardcore group of them always go to TAM.)

Anthony Watts posted up Mann's talk at this event by an attendee, here. A lecture like Rob's would be a perfect, graphic refutation of Mann's many follies, and thus highly educational for these sorts of wildly misled science fans.

Oct 21, 2013 at 10:43 AM | Unregistered CommenterOrson

," Rob is no kind of a sceptic "

I would disagree with that description, based on this article.
Rob Wilson appears to be a man who's crock is empty.
That, in my opinion, makes him the very best kind od sceptic.

Oct 21, 2013 at 10:53 AM | Unregistered Commenterpesadia

The best thing about this presentation, as described, is the conclusion that the IPCC is a crock of faeces for having given such prominence to the Mann paper. If they got it so wrong for TAR then how much is wrong with FAR, SAR AR4 and AR5.

Oct 21, 2013 at 10:54 AM | Unregistered CommenterRichard of NZ

Socrates did not have anything to do with Rome and lived and died several hundred years before Rome conquered Greece. So unfortunately Phillip's crock seems to be full :)

Oct 21, 2013 at 11:13 AM | Unregistered CommenterAthenian

I think Andrew's description of Wilson as "no kind of sceptic" points up the difficulties we face in trying to define anybody's stance on climate science.
If a sceptic is one who disputes that the mainstream ("consensus") position on climate is wrong and that modelling the climate is at best a futile exercise given the current state of knowledge then Wilson is probably not a sceptic though given the content of this lecture, presuming the synopsis is fairly accurate, that is not certain.
As Richard Tol points out, there are honest men in climate science or at least in this case one man prepared to call it as he finds it which puts him (in my view) in much the same situation as Judith Curry.
What makes me warm to Wilson is his description of MWB98, "an early attempt at a millennial reconstruction ... that it did at least attempt to discern spatial variability, something that had not previously been done" but which was "[u]ltimately a flawed study".
I don't have a problem with Mann et al producing a paper that in the event turned out to be less than reliable in what it set out to do. My problem, and I suspect where most sceptics would join me, is in the manic defence of this and subsequent equally dubious papers combined with a quasi-religious obsession which is at odds with anything resembling scientific probity.
If Wilson is moving away from that position (assuming that he was ever in it in the first place) towards an open-mindedness to at least considering some of the counter-evidence then it doesn't really matter whether you call him a sceptic or a realist or even, heaven be praised!, a scientist.
Hopefully there will be more like him but it will need a few prepared to speak out against the crock of ordure which continues to be spouted by the likes of Ward and the eco-fanatics for whom the science (whatever they say) is infinitely less important than the sociology.
At the risk of repeating myself, their patron saint is Timothy Wirth who gave the game away with the line: "We've got to ride the global warming issue. Even if the theory of global warming is wrong, we will be doing the right thing -- in terms of economic socialism and environmental policy."

Oct 21, 2013 at 11:19 AM | Registered CommenterMike Jackson

The problem is NOT the current climate science. Everyone knows, to borrow from the points made above, that that's a crock of shit.

The problem is the psychological marketing process. The Team have carefully arranged it so that their crock of shit was defined as unquestionable, and so that anyone who questioned it was an evil madman who should be NEVER be listened to. You will recall that many 'refutations' of people like Steve McIntyre and John Daly in the early years did not address the climate issues, but instead comprised a continuous repetition of:

"He's filth, he's a murderous criminal, he's an ugly, sick insane traitor to the human race..."

This seems to have had quite an effect amongst the Universities. It is therefore remarkably heartening to hear sense being spoken in academia.

Oct 21, 2013 at 11:23 AM | Unregistered CommenterDodgy Geezer

Mann being Mann, obnoxious email exchanges will follow trying to make StAndrews recant

Oct 21, 2013 at 11:27 AM | Registered Commenteromnologos

The Bishop wrote, "Mann's most recent area of focus, the influence of volcanoes on tree ring growth."

I thought that Mann's most recent area of focus was Twitter.

Oct 21, 2013 at 11:53 AM | Unregistered CommenterSpeed

"Excrete" is, biologically speaking, the wrong word, and even dictionaries can get this wrong. One excretes urine and sweat, for example, as they represent substances that have been generated by the organism. Faeces hasn't; it's mostly what's left over when most of the nutrients have been extracted from food. It's complicated by the fact that in some organisms, e.g. birds and reptiles, true excretion products like uric acid can be defecated.

Oct 21, 2013 at 11:53 AM | Unregistered CommenterMichael Larkin

Dum spiro spero.

Excellent news. The poor quality of so much 'science' that has been hyped in and around the IPCC about climate scares is deserving of more such public sharing by those in academia. In the UK, virtually all of the climate establishment has been hired, and promoted, for and because of climate scares over the last 30 years or more - to the extent that journalists struggle to find active climate scientists they would class as 'sceptic'. Geographers such as Parry and Hulme played no small part in this unsettling transformation of a corner of scientific endeavour in the 1970s and 1980s, so perhaps it is encouraging that one in the form of Dr Wilson, is taking a lead in promoting a more critical, less intellectually totalitarian view of one bit of that corner. Prof Tol is another deserving of admiration for both his intellect and his courage.

It is quite shameful for 'climate science' (in quotes since it is not very well defined) that such courage is required to challenge massively-promoted views widely adopted by political establishments. Unhealthy too.

Oct 21, 2013 at 11:56 AM | Registered CommenterJohn Shade

This week's QI contained an interesting graph about the aging of 'facts' in cutting-edge scientific and cultural studies.

They estimated that approximately 60% of the known 'facts' from the first series, broadcast in 2003, had been subsequently modified or completely overturned. QI concentrates on obscure and often very recently published information as its source material - and as you'd expect, much of this is not subsequently confirmed, despite being peer reviewed.

If there is any truth to this aging of facts, it seem likely that the TAR was around 65% wrong, and the older reports worse. In which case, surely AR5 should be explicitly correcting all the earlier errors, instead of just being even more sure of the same facts?

Oct 21, 2013 at 11:58 AM | Unregistered Commentersteveta_uk

Philip B Your posts are almost always well-argued and educational, but I fear your source, the Urban Dictionary, may have mixed up its Greeks and Romans, unless the spoof quote from Socrates was intended as an elaborate joke on all of us.

Oct 21, 2013 at 12:00 PM | Unregistered CommenterDavid S

The reason there was no attempt at global reconstructions before is that people then knew that there was not enough data to do so. They were right! And that is still the case. It's also clear from the climategate emails that few people in the field believed Mann's dross at the time either but they qall kept quiet to keep a united front against the carbon menace.

Experience says that declaring yourself as a skeptic is enough to prevent anyone listening to anything you have to say; after all if someone is anti-science and disagreeing with the vast majority of clever people then why bother to even listen? It also gets you disinvited from the parties in Cancun, Fiji etc and prevents you ever getting a prestigious prize of the type that go to Mann, Hansen, Emmanuel, Erlich etc (akin to rewards for being continually wrong but for for the "right" reasons).

Oct 21, 2013 at 12:03 PM | Unregistered CommenterJamesG

"Dingo's kidneys" are the preferred term of opprobrium in this house, but crock of shit works, too. If it was OK for Socrates (or his Roman equivalent)...

Oct 21, 2013 at 12:03 PM | Registered Commenterjamesp

I daresay that QI bothered to listen to skeptics of their asserted "facts". What a pity everyone doesn't follow that example.

Oct 21, 2013 at 12:07 PM | Unregistered CommenterJamesG

Re; Iain Stewart's particular crock - The Climate Wars.

I would have cheered at that point. One of my hopes would be a severe, point by point rebuttal of it all somewhere on prime-time. It can't be easy to be offered a free trip around the world, on great pay, to tell a few fibs about climate to the great unwashed when you have two children to feed. A trip through the sausage machine, some exaggerations and a few mistruths are no obstacle to getting your beliefs across in the guise of science. Climate scientists, even the chemists and atmospheric physicists, I let off the hook now and again. They have such poor 'climate' data to work with. The field/cause can support many activists because it is young and populated by ... well (to the general public), people like Mann, Hanson, Cook, Gleik, Lewandowsky, Santer, Ramsdorf, Jones, Schellnhuber, etc. But a geologist? Nope. There is no excuse for not showing the conclusions about co2, wrt climate, that their data leads them to - hence the vitriol Bob Carter and others attract. As to the misdirection and the other similarly odious ... stuff, well, I can dream of justice but, I fear, the major players have all been purchased and these creatures can spout all their bs with impunity - and with an ever growing confidence that the avoidance of the civilized constraints to which the rest of us must adhere in our dealings with the public is endorsed and encouraged by their handlers, allegedly.

Oct 21, 2013 at 12:17 PM | Unregistered CommenterHenry Galt

Apologies to all. I should have given the source of the quote as the Urban Dictionary.

Oct 21, 2013 at 12:20 PM | Registered CommenterPhillip Bratby

Well done to RobW in showing some much needed scientific integrity in this area (being churlish; better late than never).

Along with JamesG above, my view is it is clear that there just isn't enough data. True error bands would be floor to ceiling, i.e. we just don't know. Nice work if you can get someone to pay you to play around with the data for years but ultimately pointless.

It does seem the "climate" is changing to allow a few more academics to crawl out into the light and say perhaps the Emperor has no clothes. Good.

It's why I was so disappointed with our friend RichardB over the AR5 SPM. He had a perfect opportunity to fess up "it's NOT as bad as we thought" but instead chose to defend the indefensible like that horrendous "spaghetti bolloxnese" graph.

Saying it's hidden in the report somewhere is not good enough, it should have been THE headline news not that 95% certainty crapola.

Oct 21, 2013 at 12:38 PM | Registered CommenterSimonW

The faecal content of a crock seems an unlikely story on three counts.

Firstly Roman amphorae had pointed bases, and normally leaned against things. So establishing whether one was full or not would not be a simple matter.

Secondly, the level of faeces in an amphora seems like a poor proxy measure of dissatisfaction with an orator, because one could only express one’s dissatisfaction if the timing of one’s digestive processes permitted it. As this cannot be relied upon, then in effect, the data are contaminated by false negatives (no data received from people who would have expressed disfavour, but couldn’t) and - to a lesser extent - false positives (people quite content with the oratory, but who voted involuntarily against, on an any-port-in-a-storm basis).

The data from each crock could thus be a better indicator of proximity to mealtime than to speech quality; so while it’s a proxy, it’s a proxy for something other than what the organiser imagines.

Thirdly, the satisfaction level must depend heavily on how standardised the crocks are. If there is no norm size, with a standard deviation defined and allowed, then one could fiddle the results by short-centring – eg by supplying rivals with a smaller crock than one's own so as to accelerate their elimination.

I think I've put it as delicately as possible.

Oct 21, 2013 at 12:49 PM | Unregistered CommenterJustice4Rinka

@J4R: You've successfully pooh-poohed the idea, I'll allow.

Oct 21, 2013 at 12:53 PM | Unregistered CommenterSackerson

Although I vetted Andrew's post, I want to clarify that my 2 hour lecture was, I hope, a critical look at all of the northern hemispheric reconstructions of past temperature to date. It was not focussed entirely on Michael Mann's work. I described each of the major studies and tried to highlight both their strengths and weaknesses - they all have some useful information but it is important to understand the limitations of the studies as well. Of course Mann's work was mentioned as several of his papers have been so prominent over the last 15 years but I actually spent substantially more time taking apart the D'Arrigo et al. (2006) study on which I did much of the analysis.

This was a session where I wanted the students to critically look at the different studies and specifically address what we can learn from them and how the science can move on over the next decade. Such large scale reconstructions are critically important for understanding the controls on large climate variability, but as yet, due to great uncertainties and large differences in reconstructed amplitude, they are not yet very useful at constraining modelled estimates of future temperature change.

Bar some personal comments, much of what I said is published (see papers below) and is in the public domain.

Lastly, the "crock of xxxx" statement was focussed entirely on recent work By Michael Mann w.r.t. hypothesised missing rings in tree-ring records (a whole bunch of papers listed below). Although a rather flippant statement, I stand by it and Mann is well aware of my criticisms (privately and through the peer reviewed literature) of his recent work.


I hope all the PDF links below.

Edwards, T.L., Crucifix, M. and Harrison, S.P., 2007. Using the past to constrain the future: how the palaeorecord can improve estimates of global warming. Progress in Physical Geography 31 (5), 481-500.

D'Arrigo, R., Wilson, R. and Jacoby, G. 2006. On the long-term context for late 20th century warming. Journal of Geophysical Research, Vol. 111, D03103, doi:10.1029/2005JD006352

D Frank, D., J. Esper, E. Zorita, R. Wilson. (2010). A noodle, hockey stick, and spaghetti plate: a perspective on high resolution paleoclimatology. Wiley Interdisciplinary Reviews Climate Change. doi: 10.1002/wcc.53.

Trieste 2008 Paleoclimate Uncertainties Workshop, Final Report.

Esper J, Frank DC, Wilson RJS (2004) Climate reconstructions - low frequency ambition and high frequency ratification. EOS 85, 113, 120.

Esper J, Wilson RJS, Frank DC, Moberg A, Wanner H, Luterbacher J (2005) Climate: past ranges and future changes. Quaternary Science Reviews 24, 2164-2166.

Mann et al. 2012. Underestimation of Volcanic Cooling in Tree-Ring Based Reconstructions of Hemispheric Temperatures, Nature Geoscience, 5, 202-205.

Anchukaitis, K. et al. (2012). Tree rings and volcanic cooling. Nature Geoscience. 5: 836–837. doi:10.1038/ngeo1645

Mann et al. (2013). Discrepancies between the modeled and proxy-reconstructed response to volcanic forcing over the past millennium: Implications and possible mechanisms. JGR. 118, 14, p. 7617-7627.

Esper J et al (2013) Testing the hypothesis of post-volcanic missing rings in temperature sensitive dendrochronological data. Dendrochronologia. 31 (3): 216-222.

Esper J et al (2013) European summer temperature response to annually dated volcanic eruptions over the past nine centuries. Bulletin of Volcanology 75, 736, doi: 10.1007/s00445-013-0736-z.

St. George et al. (2013). The rarity of absent growth rings in Northern Hemisphere forests
outside the American Southwest. Geophysical Research Letters 40, doi:10.1002/grl.50743

D’Arrigo, et al. (2013). Volcanic cooling signal in tree-ring temperature reconstructions for the past millennium, Journal of Geophysical Research, doi:10.1002/jgrd.50692'Arrigoetal2013.pdf

Oct 21, 2013 at 1:12 PM | Unregistered CommenterRob Wilson

Mann has already started twitter-marketing this blog post :-)

'Closet #climatechange #denier Rob Wilson, comes out of the closet big time: … #BadScience #DisingenuousBehavior'

Oct 21, 2013 at 1:47 PM | Unregistered CommenterEspen

@Rob Wilson

thank you

Oct 21, 2013 at 1:48 PM | Unregistered CommenterDolphinlegs

Oct 21, 2013 at 1:47 PM | Unregistered CommenterEspen

Wow! Thanks, had a doubt that Mann could be so crass so had to see for myself, but yes, Mann brings out the denier accusation when he feels personally challenged!

Here's a linked version:

Closet #climatechange #denier Rob Wilson, comes out of the closet big time: … #BadScience #DisingenuousBehavior

Narcissism on stilts.

Oct 21, 2013 at 1:56 PM | Registered CommenterThe Leopard In The Basement

one of the insights in the climategate emails was how poisonous M Mann's involvement was, for the community (ego due to IPCC and Hockey Stick)?

this tweet, just now.

Michael E. Mann ‏@MichaelEMann
Closet #climatechange #denier Rob Wilson, comes out of the closet big time: … #BadScience #DisingenuousBehavior

I'm sure Dana and/or Cook, will be debunking Rob, and labelling him a climate misinformer, anytime soon.

Oct 21, 2013 at 2:03 PM | Unregistered CommenterBarry Woods

I think the "denier" epithet may have just jumped the shark ;)

Oct 21, 2013 at 2:05 PM | Registered CommenterThe Leopard In The Basement

Mann did actually send that tweet calling Wilson a denier (in case anybody thought it was a joke). So instead of responding to Wilson's specific criticisms, Mann goes ad hom. In defense of Mann, it is hard to be nuanced in 140 characters, so much easier and quicker to go ad hom than to construct a reasoned rebuttal.

Oct 21, 2013 at 2:25 PM | Unregistered CommenterSteve Koch

When the AR5 came out, on the main BBC News, Shukman did a location clip from Bangor U waving a hockey stick around, based on a clam proxy. Paul Dennis was challenging him on it. Anyone know what happened?

Oct 21, 2013 at 2:44 PM | Registered CommenterPharos

I believe what we're seeing here, and in AR5, is the next generation of climate scientists "asserting" themselves. Few, if any of them, have the same skin in the game as the Manns, Jones, Slingos etc. and although they believe that humans are the cause of the rise in temperatures (as I do, at least some of it) they themselves haven't participated, at least only at a junior level, in the political campaign.

As the years have passed these younger scientists are less dependant upon the patronage of their elders, and, unconsciously I believe, have moved back to the real scientific method where the data and observations are king and queen. They still "believe", and may continue to do so, but they're not overtly political, nor in direct contact with the sort of funding and "fame" the original hockeyteam got from their 15 minutes of publicity, hence they tend to follow the data and observations with, shall we say, a little more reverence than the elders, and are finding, I guess to their surprise, but not ours, that the data aren't saying nearly as much as they'd expected about CAGW. Being unpoliticised scientists, and not in the pockets of politicians, they are telling it as they see it and finding those they once thought could stop them/damage their careers, as they have done others, are powerless in the face of the reality of a hiatus that can't be explained.

Unlike Slingo, they don't see themselves needing to get out of the woods to save their reputations, indeed they may have in their mind that the future "reputations" of their mentors and heroes stand to be in tatters once this whole CAGW blows over, but they are still taking the science where the data, not the politics takes it. At least I hope so.

Oct 21, 2013 at 2:45 PM | Unregistered Commentergeronimo

Am I the only one appalled by Mann's action of supplementing "denier" with "coming out of the closet?" I wonder how long this string will become?

Thank you, Professor Wilson.

Oct 21, 2013 at 2:47 PM | Unregistered CommenterTheo Goodwin

@Oct 21, 2013 at 2:25 PM | Unregistered CommenterSteve Koch

In defense of Mann, it is hard to be nuanced in 140 characters, so much easier and quicker to go ad hom than to construct a reasoned rebuttal.

Don't know how serious you are there but whenever I see that defence used for faux pas comments on twitter I always like to remind people you really do have the option of not saying anything at all on it ;)

Anyway Tamsin Edwards has strongly picked up Mann on twitter for a while until he ran away, some examples:

@MichaelEMann You are seriously calling Rob a denier for criticising your work, M? That's pretty strong to call a prof climate colleague.

@flimsin Not for criticizing my work, but for apparently regurgitating #denialist drivel by the likes of McIntyre etc.

@MichaelEMann Is it not better to tweet which criticisms you disagree about, a technical response, rather than call him "denier"?

Tweet of support from a fellow dendro: Scott St. George

Rob Wilson (U St. Andrew's) is a fine dendrochronologist and paleoclimatologist, a thoughtful scientist, and 100% not a 'climate denier'.

Oct 21, 2013 at 2:48 PM | Registered CommenterThe Leopard In The Basement

Jumping the shark is exactly the phrase I nearly used to him. Rob, thanks for the citation. I stuck up for you on Twitter and it drew his fire for a bit...


Oct 21, 2013 at 2:50 PM | Unregistered CommenterTamsin Edwards

Pharos, I put in a complaint to the BBC and got an anodyne response from them to the effect that the research group ahd a good reputation therefore it wasn't necessary to check the provenance of the plot or the data. I know the area where these clams were collected (The North Iceland Shelf) and I also know that there are temperature measurements going back some considerable time at this site that show there is no significant change in water temperature. I contacted the researchers and they told me the data are not published, was preliminary and awaiting calibration. The key issue is that the clams are collected from an area where several different water masses merge, each having different isotope characteristics. Tus what is purported to be a temperature variation may in fact be a signal that currents have changed slightly. I've asked them to send me details when they have them.

The hockey stick that Shukman showed had a 20th century temperature rise of over 5C for this area of the shelf. The clams were collected in 70m of water. Using growth dynamics of these clams the same research group have published temperature histories for the shelf which in fact show a flat to slight cooling trend for the North Iceland Shelf.

So what we have is a hockey stick being presented which doesn't have any validity at all. It represents how far BBC science reporting has slipped when the message is everything and veracity nothing.

I'm going to keep a close eye on this data set and the way it is reported and published.

Oct 21, 2013 at 2:56 PM | Unregistered CommenterPaul Dennis

Michael Mann is out of bed, and all the action is on Twitter.

Oct 21, 2013 at 3:02 PM | Unregistered CommenterRichard Tol

Unfortunately Joe Bastardi has joined the twitter war in a most disruptive way - could almost be designed to ensure Mann doesn't drop himself further into the crock.

Oct 21, 2013 at 3:12 PM | Registered Commentersteve ta

That tweet from Mann attacking one of the British Establishments "own" might very well open up peoples eyes to the language used.

its alright calling "right wing US loonies deniers"... that was ok..... but coming after a thoughtful professor......

Will possibly really start and wake up academia to the unacceptable language in the climate debate.

Very Very massive blunder from Mann..... He has just basically read a skeptical blog critiquing him. without knowing anything about the person involved

*Pop Corn time*

Could be the final straw one could hope.

Oct 21, 2013 at 3:13 PM | Unregistered CommenterJustAnotherPoster

Has the twitter thread been disappeared?

Not sure, but it looks like the Mann has removed the original denier/closet tweet.

Oct 21, 2013 at 3:14 PM | Registered Commentersteve ta

Oct 21, 2013 at 3:13 PM | Unregistered CommenterJustAnotherPoster

The Mann Twitter phenomenon leaves me speechless. Why haven't his lawyers cancelled his Twitter account? In the old days, making remarks similar to Mann's Twitter remarks would get you the label of "abrasive." That was considered a bad thing.

Oct 21, 2013 at 3:19 PM | Unregistered CommenterTheo Goodwin

"without knowing anything about the person involved"

Michael does know Rob well in a professional capacity. Which is why I was so shocked.


Oct 21, 2013 at 3:20 PM | Unregistered CommenterTamsin Edwards

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