Bishop Hill Skeptical Science on the divergence problem
Apr 16, 2011 Climate: MWP 
Richard Muller is taking flak from both sides, which I guess was inevitable when such a prominent figure enters the climate fray accompanied by a great deal of media attention. The latest set of potshots has come from Skeptical Science, which has posted a new article this morning looking at some of the things it says Muller got wrong in his widely reported lecture on "hide the decline".
A couple of things interested me about the Skeptical Science article or, more precisely, its companion piece published at the end of last month. In this piece, I'm going to discuss the article's consideration of the divergence problem:
...the decline in tree-ring density is not a hidden phenomena - it's been openly discussed in the peer-reviewed literature since 1995 (Jacoby 1995) and was also discussed in the IPCC Third Assessment Report (TAR) and Fourth Assessment Report (AR4).
I think the characterisation of the discussion of the issue in the Third Assessment Report as "open" is not a reasonable one. Here is what the report had to say on the issue
There is evidence, for example, that high latitude tree-ring density variations have changed in their response to temperature in recent decades, associated with possible non-climatic factors (Briffa et al., 1998a). By contrast, Vaganov et al. (1999) have presented evidence that such changes may actually be climatic and result from the effects of increasing winter precipitation on the starting date of the growing season (see Section 2.7.2.2).
"Variation in response" hardly characterises the decline very well, does it? Would a reader of this section have understood that these tree rings were headed off in the opposite direction to that expected? Were the implications discussed? And there was no discussion of the truncation of the record in order to hide the change in response (i.e. the decline) either. I don't think Skeptical Science has got this right.
But there was also this:
it bears remembering that other research finds tree-ring density is reliable before 1960. Briffa 1998 finds that tree-ring width and density show close agreement with temperature back to 1880. The high-latitude tree-rings that show divergence after 1960 also match closely with other non-diverging proxies going back to the Medieval Warm Period (Cook 2004). This indicates the divergence problem is restricted to modern times.
Now this is a bit naughty. Cook did indeed suggest that the divergence was restricted to modern times, a paper that reasonable people can probably agree is not a firm basis for disposing of such an important question. But even the Fourth Assessment report quoted D'Arrigo et al saying that the divergence problem might be a manifestation of a non-linear response to temperature, something that would undermine the whole of the tree-ring approach to paleoclimate. And a still more recent paper describes the evidence restricting the problem to the twentieth century as "limited". For Skeptical Science to pretend otherwise seems to me to be...a problem.
Reader Comments (78)
Leopard, I liked your point about grammar! BBD's heart is in the right place but he likes to pick a fight. This is a blog after all...
Skeptical Science is pathetic. Always claiming that someone has been debunked because they used 'can' not 'may' or some similar scientific Crime Of Major Proportions - never engaging with the key points. I wonder if anyone can think of any previous scientific story where Running Dogs sprang up to defend the new orthodoxy so persistently? Thos Huxley was Darwin's bulldog, but I seem to remember he knew what he was talking about first hand also.
TLIT Basement
You say:
And I agree. What worries me is the repeated attacks on Muller and BEST from some sceptics.
I'm guessing that by 'putting down a purse' you mean place your bets and be clear about what you are betting on?
If so, I have already done it. I've been clear in this and other threads here that Muller deserves credit for criticising the consensus. I'm betting he is more credible than Cook because Cook is the one defending the indefensible.
j
If you know where my heart is, please provide a link. I haven't been able to find the blasted thing for several years...
And I prefer to think of myself as questioning the questionable, rather than picking a fight, but as you say, this is a blog ;-)
Someone pinch me, does the entire Skeptical Science article really hinge on an affirmative-action parsing of the email in question? I'm serious, somebody straighten me out if I'm wrong here.
From the article:
In the above, I read a phrase "each series for the last 20 years (ie from 1981 onwards) and from 1961 for Keith’s" that is the subject of the preposition "to". In that phrase Jones states that he added "real temps" to every series. For most of them he started at 1981, but for "Keith's" he started at 1961. The object of his additions is to "hide the decline". "Mike's nature trick" implies that "Mike" first introduced this postmodern data processing technique in "Nature". (Ok, I snark a little. Sorry.)
The, um, "Skeptic" reads Jones differently:
The Skeptic insists, but does not support. Perhaps he has read Jones as "I've just completed A and B". A is "Mike’s Nature trick of adding in the real temps to each series for the last 20 years (ie from 1981 onwards)". B is "from 1961 for Keith’s to hide the decline." Even if this parsing was grammatically valid, wouldn't the choice still strike you as unwisely charitable? It does me.
Ugh, reading over this I see I have to apologize for gross pedantry. Still, one must rise to the occasion. Are these people for real?
Again, again, lookin' at Cook it seems a bit sloppy with his references. In Cooks "Muller Misinformation #1: confusing Mike's trick with hide the decline" article he shows a colour diagram of the Briffa Low-Frequency Density changes construction against temp, but then links to a 2000 paper with a simliar looking black and white graph but with a totally different LFD (worse fitting IMO) visual cue is the dip at 1544 in the B&W graph. Eh? How many Briffa reconstructions from 2000 are there to choose from?
I've been looking at this for a while trying to work out my obvious mistake and going crazy wondering but now I realize Cook always seems to link to the same post with same B&W LFD when referencing the other colour jpeg. I am not a scholar or a gentleman so I wonder how this works just getting your references wrong?
If I could be arsed I would check out the Climate Audit archives to find out. But do you guys know where the colour Fig. 5 comes from?
BBD, a bit of robust argument with each other is good fun for all. And this is indeed a blog - a far better one than Skeptical Science, that's for sure. Someone above bemoaned the fact that Simon Singh referred to Skeptical Science as gospel truth. I agree: what a silly site it is. Has anyone ever looked at Lubos Motl's rebuttal of Skeptical Science? Good fun.
BBD : "You seem to be suggesting either confirmation bias or misconduct. There is evidence for neither."
"confirmation bias" would be my view (of a lot more than just the temperature record or paleo). I'm not even suggesting that they are wrong but it seems to me that if you set out with a particular result in mind then your thinking while designing your model is likely to reflect that expected result. This is as applicable to science as it to any other human endeavour. I design machines in software and am more than familiar with getting myself "stuck in a rut".
Explain to me what exactly Muller will do if his first "global" run indicates a 5C warming over the last 100 years? How exactly will he "know" that the 5C figure is incorrect? As far as I can see he will "know" that 5C is "incorrect" by "instinct" and re-design the model accordingly.
My design of a rubber, earthquake proof, building worked fine in my simulation until some "second opinion" dialled down the ambient temperature. My building cracked and fell in a moderate wind. In "climate science" I'm just not seeing much of that "second opinion".
"And I agree. What worries me is the repeated attacks on Muller and BEST from some sceptics."
Why does criticism in climate science have to always morph into an "attack"? My criticism of Professor Muller was simply that he appears, on the one hand, to want to re-examine the instrumental temperature record from the bottom up, without bias, and on the other hand he "knows" what the outcome will be. In my view you can't have it both ways. If neutrality or cooling are not options then why expend the energy in the first place?
Ultimately, I guess, prof. Muller et al really don't see the billions being made by Goldman Sachs and Deutsche Bank (for example) as we here argue the toss over 0.x degrees in 100 years. (No reduction in CO2 incidentally). As far as I'm concerned - useful idiots as Stalin might have said. That's the Ivory Tower for you.
(still way OT though)
Nice post. But can you tell me how do I get the feed o your site climategate.nl . I would love to know that cheers.:)
3x2
It's science. Replicate or falsify. BEST is another go.
Why do you think the preliminary BEST results indicate warming?
Well i have bookmarked your web site climategate.nl for future referece.:)
Well can I use some of your post to my website. I will certainly give a attributable link to climategate.nl if i use any details. Tell me if you don't have any problems with it. Regards :)
As per my guess your web site climategate.nl has a really clean and simple look. I can try to be creative just like your site.
Well I had book marked your web site climategate.nl for future referece.:)
As per my guess your web site climategate.nl has a really clean and very simple look. I will try to be creative just like your site.
Sorry, I typed the link to Lubos Motl's rebuttal of Skeptical Science's rebuttal of sceptics' arguments in my previous posts. Lubos writes in shorthand so can be hard to follow, but for those who can be bothered, its worth a look!
BBD
Where did I say that it was not warming? Did you read what I posted?
I'm specifically stating that Muller attributed the warming to humans saying " It's us ". Did he say it or not?
Nobody denies that it has warmed in thee last 150 years or so as we are coming out of the LIA.
How did Dr.Muller decide based upon 2% of data that the reason for the warming is " us "? That was my question. How can he attribute humans as a reason for warming when he has not completed the analysis of the full data, as per his own statements?
Venter
Yes. Let’s get this sorted out.
I originally pulled you up for distorting what I said (see April 17 7:06pm).
Absurdly, you denied this and once again inserted Muller's comment about attribution into the exchange. You know, the one I didn't actually mention in the first place. The one you seem keen to talk about even though it had nothing to do with my original point. The one you are still trying to insert into this exchange and pick a fight with me about.
You go on to say:
In an earlier comment, you said:
Your real aim is Muller-bashing. Your ‘argument’ is that Muller should not have made any comment about the attribution of the warming evident in the preliminary BEST results.
You claim that Muller’s statement reveals a bias and BEST is compromised as a result.
This is nonsense of course. Muller isn't basing his views on anthropogenic attribution on the '2% of data' and BEST's incomplete analysis. He is basing them on his overview of the entire debate.
Nor is BEST an exercise in attribution. It is a surface temperature reconstruction. You are (deliberately?) confusing the two.
Since you won’t accept any degree of anthropogenic influence on climate, you question Muller’s integrity and imply that BEST is a fix, not an ‘objective analysis’.
That makes you guilty of exactly what you wrongly accuse Muller of. Gross confirmation bias.
I object to that mentality just as much as I object to you putting words into my mouth. Two sides of the same coin, really.
Bish could you kindly dispose of Mr S Panels.
Thanks
BBD,
You are the one putting words what I never said. I stand by what I said. There may or may not be AGW and your belief is as good as mine. But it is still only a belief. The day it gets proved is when somebody can separate the natural and anthropogenic warming signals and show that it is " us " who cause it. That is the day when the AGW theory will be proved.
So you are the one with a confirmation bias here already acting as if AGW is proved. Till empirical evidence shows that human emitted CO2 causes unprecedented global warming, nothing is proven.
Muller said it is " us ". Until he shows his work and analysis and proves that it is " us " conclusively, it remains an empty statement.
And maybe it my have escaped you, but in the past when people who already had a fixed positive opinion on the AGW theory were given the charge of gathering data prove it, the torture of the data and methods has been seen and it is not pretty or scientific.
So having been bitten once or many times for that matter, I'm waiting to be convinced and will be glad to accept any result as it falls with regards to AGW provided it is open with methods and data shown and stands the testing by it's best friends and worst enemies.
As of now, based upon work done by GISS, CRU and their cohorts, my belief is that AGW is a scam. But I'm willing to be corrected if proper science shows it is true.
Venter
So, you still don't accept that you distorted my comments and continue to do so as I describe above? And now I'm in the wrong (again) for daring to object to your cavalier way with (my) words?
On that basis, I'm going to ignore most of your comment in the same way you have ignored mine.
However, there is this to think about:
If you think GISS and Hadley/CRU are faking the surface temperature data, why does it agree so well with the satellite data showing tropospheric warming?
The correspondence is good both for interannual variability and trend over the 32 year period of satellite observations.
The obvious conclusion is that GISTEMP and HADCRUT are broadly correct.
Where does this leave your assertion that 'based on work done by GISS, CRU and their cohorts [...] AGW is a scam'.
I've set it all out on the Discussion thread (top right of the main page). Do please go and have a look.
We can argue the toss about attribution all night, although you might be surprised to learn that I suspect the consensus estimate for climate sensitivity to CO2 is too high.
Hence the lower than expected warming trends over the 32 year satellite period and perhaps too the hiatus in warming over the last decade.
All I can say is if Muller is taking flak from both sides, he must be doing something right. Or demonstrating just how polarised and politicised the debate is. Or how difficult it can be to remain an 'honest broker' in the climate world. BEST has certainly generated a lot of excitement and speculation despite not having published any results.
BBD, if you take a second to read properly I talked about work done by GISS, CRU and Co about AGW, got it? In capital letters AGW.
I never said there is no warming.
Satellite data is there only since 1979.
I said that due to their games with the proxies, truncation and hiding the decline to show that current warming is unprecedented, due to Hansen constantly applying adjustments which diminishes past temperatures and raises present temperatures, due to antics in spreading warming in the Artic where GISS has no thermometers, due to GISS showing aa fairytale anomaly of + 0.57 degrees for March when RSS and UAH show a negative anomaly, due to the model predictions being falsified by empirical observations etc. etc. etc. etc. There are many other reasons which I have no time to elaborate.
One of the fundamental reasons of course is that nobody has shown any empirical, testable, falsifiable evidence showing human induced CO2 to be the only reason for the warming and accurately separating the natural and anthropogenic parts of it.
Antidisestablishuniformitarianism.
========================
Venter
Oh come on, man. This is just... silly.
You aren't being straight with me and we both know it, so I think that will have to be it for the time being.
When you learn to argue like an adult, we can try again.
If you can refute what I stated with facts, I'll be glad to accept. I've seen zero facts too many ad homs as last line of defence from AGW defenders.
BBD
"If you know where my heart is, please provide a link."
Quite pointless but very funny.
Venter
You say:
And:
You have managed to tangle and twist this exchange so much that it is now virtually meaningless.
However, if you really are interested in facts, then go across to the Discussion thread and read what I posted about comparing TLT satellite temperatures with surface temperatures.
It is directly relevant to what you say re Arctic interpolation and odd GISTEMP anomalies. It shows how, in the big picture, they actually make very little difference.
Rather like UHI in fact, which was what I was trying to demonstrate.
For future reference, please note that I prefer directed arguments in which:
- all protagonists refer back to previous statements and address them directly
- all protagonists refer back to previous statements accurately
- all protagonists stick to the point and do not obfuscate
- all protagonists honestly admit errors
sHx
Life at its best.