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THREAD RULES. BE POLITE. NO AD HOMS (trying to prove argument by attacking the integrity of the arguer. It is fine to show specific instances of incompetence etc if directly relevant). KEEP TO THE TOPIC.

Lensman challenged me on another thread, saying that it was obvious Mann suppressed information with his infamous "hockey stick graph"

The argument for this is summarised by Lensman as follows:

 

Lensman said:

Here is a temperature graph of the past 1000 years published in 1990. Was it from some global warming skeptic blog? No, it's from the IPCC's own official executive summary for that year:

 

 

 

 

 

 

 

 

 

And here is the infamous "hockey stick" graph which pretends to show the temperatures for the same period, the past 1000 years:

[Edited to remove ref to malware alert site "churchofglobalwarming"]

 

 

 

The suppression by Mann et al of the widespread and well-documented evidence for the Little Ice Age cannot be disputed. The evidence of the Medieval Warm Period is less well established-- current (hopefully better) data would show the maximum temperature lower than current temperatures-- but there is no legitimate reason for Mann deliberately omitting the data for the LIA.

If you deny there is clear bias shown here, if you deny that the "hockey stick" graph has been made the centerpiece of the alarmist AGW argument, and if you deny that this is a deliberate suppression of evidence of natural climate change by so-called "consensus" climate science, then it's pretty obvious just who is in denial here, Tom.

As they say: "You are entitled to your own opinion. You are not entitled to your own facts."

So let us get to the bottom of this. There are really four separate questions:

(1) Are the graphs Lensman posts, which appear to show strong disagreement, what they seem? There are lies, damned lies, statistic, and AGW-related graphs. Thre latter being the easiest to distort. So let us look at lensman's data and see what happens.

(2) is the overall Hockey Stick temperature shape correct? In other words, given the best information now, do we have a grpah looking like that?

(3) Was Mann guilty of deliberate distortion of facts etc?

(4) Is this graph the centrepiece of the AGW argumen?

I suggest we deal with (1) and (2) first. When the science on these to questions is settled we should be in a good position to tackle (3). I propose we ignore (4). It is very political - the hockey stick is a very powerful popular illustration -  but no single graph is much use at conveying the whole scientific picture. Since i am interested in the science much more than how it is presented (TP I think sometimes worries I may be giving ammunition to "the other side") I'll ignore the politics. As far as i am concerned, looking at the science, there are not two sides. Of course, in the politics there are, and internet debates which do not drill down into the detail of the science and shake it till the truth emerges can similarly polarise. I'm hoping we can avoid that sort of thing here.

Now I could post a rebuttal with a whole load of graphs, and referenced peer-reviewed papers as sources which shows in answer to (20 that Mann's Hockey Stick looks fine.

But that will not work, and would be unfair. It is necessary to post precise arguments with precise counter-arguments.

Prima facie the graph lensman posts looks damning. But is it? One thing that worries me is that it has no temperature scale. Another that we do not know over what scale it is averaged. Obviously the last bit of the hockey stick is very sharp, so if we average over 100 years or so we will suppress it.

I'll do some investigation. Perhaps Lensman can do the same.

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OK. I checked the image lensman quotes as from IPCC 1990. It is. However we need some context, because IT IS NOT SHOWING THE SAME THING AS MANN'S GRAPH.

There are two differences:

(1) It is from 1990 a time at which published large-scale (global or hemispheric) temperature reconstructions did not exist. Mann's work from 1999 had access to much more complete data sets. (remember IPCC reports are long reviews, and tend to lag the most uptodate science by a few years).

(2) It is based on Lamb's climate history for central England. (For those US readers here who don't know, UK is a very very small part of Europe, central England a very small part of the UK). UK as an island in the N Atlantic has unusual climate: much warmer than would be expected from its latitude due to the gulf stream current. So you don't expect English temperature variation to track N hemisphere temp variation.

So - just to be clear:

  • Mann - 1999 - North hemisphere
  • Lamb - 1990 - central England only


See the difference? The IPCC 1990 report does not state explicitly that this graph is from central England only reconstructions - which I guess is why people can be confused. Let us check this by going to IPCC 1990 report, finding the graph, seeing whether it refers to Lamb's work, checking that.

And BTW I agree, that lack of context in the IPCC review was careless and bad science. Of course, you find it in many other places, but the IPCC is meant to be more careful than most others, and you would not expect to find such an omission in current reports, given better review procedures.

Here is Chapter 7 of the IPCC report. this has a whole load of graphs, some look quite like the one we are looking for. I have not definitely identified it - still looking.

http://www.ipcc.ch/ipccreports/far/wg_I/ipcc_far_wg_I_chapter_07.pdf

from: IPCC1990 Ch 7 Executive summary]

We conclude that despite great limitations in the quantity and
quality of the available historical temperature data, the evidence
points consistently to a real but irregular warming over the last
century. A global warming of larger size has almost certainly
occurred at least once since the end of the last glaciation without
any appieciable increase in greenhouse gases. Because we do not
understand the reasons for these past warming events it is not yet
possible to attribute a specific proportion ol the recent, smaller,
warming to an increase of greenhouse gases.

I'll leave further ferretting into this pre-1990 graph to Lensman. Does he think it represents hemispheric data? If so why? Or does he think it is more accurate than the 1999 and after hemispheric reconstructions?

let us try and tackle the other part of this - what do modern best practice reconstructions look like? Remember that as time goes on we have new ways of estimating historic temperature not available pre-1990.

Well, a (one-sided) list of more modern hockey stick comparable reconstructions is shown here:

http://www.skepticalscience.com/broken-hockey-stick.htm

I don't expect this to settle the matter. But it does have links to source literature for what it says. The interesting thing is that we have now got ways of estimating temperatures that did not exist previously.

Another interesting thing is to note the ERROR BARS. All such reconstructions, including Mann's, have error bars. They tend to be large for anything before the twentieth century.

So when you look at this type of graph and the error bars are not given, just remember it does not mean much.

I find the BEST WAY to sort out conflicting internet opinions is to read comments on a blog where the comments are (mostly) discussing both sides of the technical case. It is not like being spoon-fed, you have to go beyond the headline statements and work out who is giving a more complete picture.

Here is a substantial section of the comments on the above "is hockey stick broken" blog. You will see that to get to the bottom of it you need to delve in to quite a bit of subsequent literature, and statistics. But worth it, if you want an informed view.

EDIT - sorry, the post numbers etc have not pasted properly, so the original is easier to read than the version below

I'm hoping lensman will read all this stuff together with his own (perhaps less biassed :) ) sources and come up with specific issues for debate in detail.

marty at 02:20 AM on 1 July, 2010
I just read an article saying that it was responsible for the hockey stick appearence and wondered if it was true that it makes temperature records have a hockey stick shape.

Obviously if there are hockey stick shaped graphs that don't include the tree ring records of bristlecone pine then the article is clearly wrong.

The article is on a site called spiked and I was rather hoping that someone knowledgeable about this issue might like to clarify things either here or in a posting to the letters page on spiked.

http://www.spiked-online.com/index.php/debates/copenhagen_article/9...

Since I haven't made up my mind about the science I obvioously flit between sites like spiked and this one.

I'll have a look at the NOAA site and if it's not too technical I'll see if I can figure it out myself seeing as no one here can just give me a straight answer to what seemed to me a straight question.

cheers
Tom Dayton at 02:29 AM on 1 July, 2010
Marty, read the post at the top of this page. See all the graphs of temperature data from sources that do not include bristlecone pines?
KR at 02:40 AM on 1 July, 2010
marty - an excellent question. Kudos to you for checking additional data sources; many people don't bother.

As Tom pointed out, there are a number of different temperature measurements (proxies) listed at the top of the page.

I believe the Mann 'hockey stick' is composed of data from ~100 different temperature estimates, including some tree ring data. Mann felt (with some reason) that the later part of the tree ring data set was distorted, possibly due to other influences (drought) on tree growth for those proxies. It doesn't really matter, though, as including/excluding the later period tree ring data doesn't really change the graph by more than a couple percent either way.

This is a popular 'skeptic' tactic, marty, which you might see elsewhere - picking a tiny piece of evidence, pointing out issues (correct or not) with it, and using that to claim that a conclusion based on many, independent lines of evidence is therefore invalidated by that tiny piece.
marty at 03:05 AM on 1 July, 2010
Ok well for the sake of trying the debate I've posted a question about this on the comments box accompanying the article with a link to the article above. unfortunately I couldn't raise KR's claim about the small difference the inclusion/exclusion of tree ring data makes since I hadn't read it at that point. I would like to see what anyone following the link will have to say.

I would disagree about the skeptic tactic bit though since it is a 'tactic' used by science in general. A tiny seemingly peripheral detail like the weird backwards looping about of a planet bought the whole glorious earth-centric universe tumbling down.

Cheers.
KR at 04:34 AM on 1 July, 2010
A small inconsistency can be an issue with a larger theory, marty - if the measurement is accurate/repeatable. Retrograde planetary transits certainly fit in that category.

Unfortunately, many 'skeptic' arguments involve disagreements on interpretation, completely incorrect data, arguments about data normalization and calibration, etc. - and each (mis)point is used to argue that the Earth isn't warming, or we aren't the cause, or it won't hurt us anyway.

An error in measurement (if it exists) is of quite different importance than a solid measurement that contradicts the theoretic predictions. I haven't seen any of those, really; the only recent issues I've seen that required consideration were ocean heating measurements and the tropospheric hot spot - and after the discussions I have to agree that these do NOT invalidate the conclusions of human driven global warming.

You might find the list John has put together of the standard arguments quite interesting.
KR at 06:09 AM on 1 July, 2010
To clarify my previous statement, marty:

An invalid measurement (paper, data, whatever) is a lack of evidence for something. It really doesn't say anything about other evidence supporting a particular conclusion, just that the particular measurement has issues.

A valid and contradictory measurement, on the other hand, is evidence against something. That's the category that retrograde planetary transits fall into.

I really haven't seen any valid contradictory evidence regarding the conclusion of human driven global warming - nothing that held up as valid under examination.
Eric (skeptic) at 22:14 PM on 2 July, 2010
KR says: "I believe the Mann 'hockey stick' is composed of data from ~100 different temperature estimates, including some tree ring data." The Mann hockey stick in MBH98 was mostly created by incorrect standardization (normalization) that overweighted the Bristlecone proxies, a simple error. If you are referring to a newer version of "Mann 'hockey stick'" then please specify what version you are referring to.
KR at 04:53 AM on 7 August, 2010
Eric - please read the last two paragraphs of this posting for an answer to that question.
pedroj at 02:31 AM on 14 August, 2010
John, I don't know what's happening with Tamino's blog, but links are not working anymore. Fortunately internet archive keeps his blog until the end of 2008. Here is the link for the post not alike.
Ned at 02:40 AM on 14 August, 2010
All of the threads from before March or so of this year are gone at Tamino's site. It's a huge loss, as there was a lot of very good information there.
doug_bostrom at 03:59 AM on 17 August, 2010
In another thread the so-far unpublished McShane and Wyner paper was pointed out by David Walters.

Some (me, for instance) have speculated that McShane and Walters drop some remarks indicating their unfamiliarity with the topic of their statistical analysis, even as they suggest climate researchers in turn are suffering from a lack of statistical expertise.

Perhaps this is in fact a problem?

1) Why did McShane and Wyner regress their proxy PCs against the global mean temperature time series rather than against the whole NH temperature field over time, like Mann does? In other words, why throw away all that detailed info and calibrate against aggregated data only?

2) Why did M&W not notice that their calibration using the first PC of the instrumental field, rather than the global mean of instrumental, gives a reconstruction indistinguishable from Mann et al. 2008?

3) …and why did they not use this calibration — also aggregated but apparently better — in their Bayesian run, when it also clearly gives the best fit even by their crippled (because again, taken relative to the instru mean time series, not the whole field) RMSE criterion?

"Gavin's Pussycat" at OpenMind

Ordinarily I don't think I'd be referring to a blog comment by a cat as opposed to a formal comment or the like but apparently this paper has been pushed into the limelight before benefiting from full review. So, fair game, I guess.
sailrick at 12:36 PM on 17 August, 2010
Regarding the supposed debunking of the hockey stick by McShane and Wyner,

"A new Hockey Stick: McShane and Wyner
August 16, 2010, by Tim Lambert

http://scienceblogs.com/deltoid/2010/08/a_new_hockey_stick_mcshane_...
doug_bostrom at 13:37 PM on 17 August, 2010
McShane and Wyner is apparently yet another smoking "gub," looks like. Nailed by their lack of expertise?

The tasty nugget at the center of the paper, for skeptics:

In other words, our model performs better when using highly autocorrelated noise rather than proxies to predict temperature. The real proxies are less predictive than our "fake" data.

It appears M&W compared the performance of proxies sensitive to regional changes against the global NH temperature record. Naturally, the thermometer on your porch (for instance) will turn out to be a poor proxy for global NH temperature if you're trying to tease out changes on the order of a couple of degrees.

Even I should have been able to see that. Rats.

Noted in various places.
Eric (skeptic) at 19:53 PM on 17 August, 2010
Re: Comparing proxies against global NH (i.e. EIV) versus regional temperature records (i.e. CPS). The two methodologies are compared in Mann 08
http://www.pnas.org/content/early/2008/09/02/0805721105.full.pdf and are also compared in the new paper (see sections 3.2 and 3.6 in Doug's link in post 26)
cruzn246 at 06:18 AM on 21 August, 2010
And that makes this time period......the 26th warmest period in the Holocene era. Big deal.
Response: See the Argument "It's Not Bad," also titled "Positives and Negatives of Global Warming."
Tom Dayton at 03:07 AM on 1 September, 2010
Deep Climate has done a detailed analysis of the McShane and Wyner paper.
doug_bostrom at 03:17 AM on 1 September, 2010
McShane and Wyner's paper was tossed into the ring of public contention prior to being graced with the full benefit of review. Presumably this was voluntary on the authors' part, or let's hope so.

DeepClimate has a lengthy post delving into various features of M&W, and as well there's a robust discussion in the comments there for folks who'd like to get caught up one way or another.

DC is not the only outfit to notice the strangely situated political freight loaded onto the M&W train of thought.
TOP at 09:31 AM on 1 September, 2010
Regarding McShane and Wyner:

Is being reviewed. We will wait with baited breath.

I guess I missed the "political freight" when I read it today. DC seemed to be going for the ad hominem argument in that regard. I would have preferred that DC skip over the jibes at political incorrectness and spent that time delving into the paper itself. There was a lot going on in those 45 pages.

McShane and Wyner take their own shot at the climatological world for being statistically challenged as well. Data is data after all and that is the world of statisticians.

One of the conclusions:

...we conclude unequivocally that the evidence for a ”long-handled” hockey stick (where the shaft of the hockey stick extends to the year 1000 AD) is lacking in the data.

In other words, there might have been other sharp run-ups in temperature, but the proxies show them. The hockey stick handle may be crooked, but the proxies can't show it one way or the other.

Note that McShane and Wyner don't necessarily think the historical record is all wrong, but rather that the anomaly signal that the global warming crowd is using is not necessarily detectable the data.
doug_bostrom at 10:22 AM on 1 September, 2010
TOP if M&W choose to include a narrative of the political history of paleoclimate studies in what is advertised as a technical critique and improvement of statistics employed in proxy temperature reconstructions, it's not an ad hominem attack when readers are arrested by this unusual feature and begin to speculate on why the extra material is included. The authors themselves after all have chosen to include this distraction; presumably they wished to call attention to their paper in this way. They've succeeded.

To wit, this example paragraph, which you apparently did not notice when reading the paper:

Quotations like the above and graphs like those in Figures 1, 2, and 3 are featured prominently not only in official documents like the IPCC report but also in widely viewed television programs (BBC, September 14, 2008), in film (Gore, 2006), and in museum expositions (Rothstein, October 17, 2008), alarming both the populace and policy makers.

Al Gore? Alarming? Really? Can you spot the statistics in that? I can't, but I do read what many would term as "dog whistle" political words.

Now do you notice how the choice to include political fluff makes it more difficult to discuss their work? Why do I have to ask, because I made M&W mention Al Gore, or because M&W chose to write about Al Gore instead of statistics?
scaddenp at 11:44 AM on 1 September, 2010
TOP - where is the ad hominem in DC's article? Ie the attempt to discredit the argument by an attack on the persons of M&W, rather than on the argument that they present? DC helpfully makes it possible to check M&W version of history is correct or not, but the teeth of article deals with the technical argument.
robert way at 13:48 PM on 1 September, 2010
It is easy to see why M & W was not submitted to a climate journal. First question they'd be asked is why they used local proxies to correlate to global temperatures and then criticized those same proxies for not being predictive of global temperatures. If they had any sense they would of compared them to the LOCAL temperatures that the proxies actually respond to...
Daniel Bailey at 05:52 AM on 27 September, 2010
Moderator:

The link to Tamino's post "Not Alike" in the Further Reading section is broken.

The actual link to where it can be accessed is:
http://web.archive.org/web/20080220174450/http://tamino.wordpress.c...

Courtesy of the Internet Archive Wayback Machine".

Tamino's posts older than March of 2010 are gone, and pre-existing links to them are probably broken. Posts older than August 22 of 2008 can be found at the archive search link provided.

Anyone have any ideas for missing posts between those dates?

The Yooper
Bodo at 05:57 AM on 27 September, 2010
As far as I know Tamino has written a book, and that may be a reason why he deleted the older post.
Daniel Bailey at 06:25 AM on 27 September, 2010
Re: Bodo (38)

AFAIK, the missing posts are a result of a dispute between Wordpress and Tamino over content. At one point, one of the two parties pulled all past content. All posts prior to March or so of this year are gone from Tamino's Wordpress blog.

Some of the missing content is still accessible, as I note.

On the subject "is the hockey stick correct" here is a nice discussion based on the reconstruction which most emphasises the LIA and MWP.

http://web.archive.org/web/20080220174450/http://tamino.wordpress.c...

It argues that even given this, the modern temperature change is extraordinary and not comparable with previous changes.

Note that there are lots of temperature reconstructions based on different things - this reconstruction is cherry picked to make the LIA MWP seems as significant as possible - it is an outlier and probably not accurate.

 

You like to argue with yourself?  :-)

 I've read an interesting novel a few months ago: 

State of Fear

by Michael Crichton

One of the interesting part I personally found about the book is the author's note at the end. A must read I must stay.

 

 

ee-tom,

Should you really be interested, try reading "The Hockey Stick Illusion."

http://www.amazon.com/gp/product/1906768358/ref=s9_simi_gw_p14_t1?p...

Tamino is not a reliable source.  For further details on the statistics used by Mann see http://climateaudit.org/

hmmm... FINALLY, eetom proved somebody was lying.  CONGRATULATONS are in order.

Good God Tom, maybe you should do a little research.  Try reading what his peers wrote to each other in the climategate emails.  If more people actually did really read everything instead of only reading the prophets of AGW(Tamino, etc ) then we might have less alarmist useful idiots for the "Team".  Parallel had a great suggestion with The Hocky Schtick.  If you have the statistic skill try reading Climate Audit and the Wegman report, try finding out about the censored directory...  Mike Mann knew that without Greybill his hockey stick fell apart, he hid that fact.  The Mann is a scientific fraud and a bully.

Better yet why don't you do some critical thinking on your own, there are many examples of the MWP and RWP being warmer than today that are out there.  Greenland's dwellings that could not exist today because it is still too cold.  Graves in permafrost today that were not permafrost when they were dug.  Mines, farms and dwellings under glaciers in the Alps that we are now just finding as the glaciers recede - meaning it was warmer when they were built/dug.

Try also reading Idso's site which lists hundreds of papers showing a distinct MWP.

Although I doubt you will because you like all believers rely on what the great mann tells you.  Coincidence though that just a couple of years after climate researchers say "we have to get rid of the medeival warm period" Mike Mann produces this POS.

OK. The Tamino post was interesting partly because it has some cogent skeptic comments (in fact it is mostly cogent skeptic comments). Those questions need to be answered.

I reject "Tamino is not reliable". It is an ad hom if stated without specific reasons.

I reject "go look at this book". If the book has specific arguments relevant you could summarise, if the book is available online you can quote page number - but it needs to be ONE or A SMALL NUMBER of argument (pick the strongest if you like) so it can be considered and counter-srguments also considered. You must realise that it is easy to post a reference to 100 pages and say "read all that, you will find you are wrong". But it does not advance the debate.

Remember also that we are arguing science, not ad hims about scientists. Easy to do these on both sides. If the scientist is bad then his specific material will be weak and can be argued.


So I will await specific arguments from the your sites.

Tom


Parallel said:

ee-tom,

Should you really be interested, try reading "The Hockey Stick Illusion."

http://www.amazon.com/gp/product/1906768358/ref=s9_simi_gw_p14_t1?p...

Tamino is not a reliable source.  For further details on the statistics used by Mann see http://climateaudit.org/

Fibb, that is contrary thread rules: OT at very least if not impolite.

Fibb :D said:

hmmm... FINALLY, eetom proved somebody was lying.  CONGRATULATONS are in order.

Hum thaks for this.I've edited to remove insults and ad homs, I will answer your points.

Hum said:

Try reading what his peers wrote to each other in the climategate emails.

If these comments advance the science you will hav eto quote them. If as I suspect you are implying that the authors and by implication Hansen is unreliable that is contrary to thread rules. If Hansen's science is bad this can be shown. Specifically. Drill down to the science issue please, because otherwise we will just get sides, with each side angry at the other.

If you have the statistic skill try reading Climate Audit and the Wegman report,

I have used PCA analysis proffesionally, and even coded PCA algorithms (which of course is quite unnecesary, ue matlab). For anyone interested there is a good non-political intro on Tamnio's site.

I'll post it when I can find it.

I'm expecting that the Wegman report, and other stuff, will be discussed. It may get a bit technical. I'm not going to accept political phrases from either side. So it needs to be technical criticism from or of Wegman, or whatever.

This is a topic where there is some merit on both sides, an dthe science is not so dificult. I will be interested to see what happens when people really look at the science arguments, without ad homs.

try finding out about the censored directory...  Mike Mann knew that without Greybill his hockey stick fell apart, he hid that fact.  The Mann is a scientific fraud and a bully.

I'm leaving that in just as example. That is ad hom. And not substantiated. And links to large web sites with a given view, rather than a specific argument, won't help. Specifics please relating to technical stuff.

Better yet why don't you do some critical thinking on your own, there are many examples of the MWP and RWP being warmer than today that are out there. 

Greenland's dwellings that could not exist today because it is still too cold.  Graves in permafrost today that were not permafrost when they were dug.  Mines, farms and dwellings under glaciers in the Alps that we are now just finding as the glaciers recede - meaning it was warmer when they were built/dug.

OK. This is arguing that hemispheric global temperatures are warmer than today because some specific sites are warmer? Specific sites can be much warmer or colder than the average for many reasons, you see examples even today e.g. some glaciers are increasing although the vast majority are decresing. I can find examples if you need them. But it is pretty obvious that changes in weather patterns (e.g. gluf stream) can have profound local affects which do not change global results. The hockey stick is N hemisphere global temps.

Try also reading Idso's site which lists hundreds of papers showing a distinct MWP.

Of course 100s of papers is too many to read. There are clearly many different reconstructions, including the Lamb central England one that Lensman highlights, which show distinct MWP. In fact I linked and highlighted one such above commented on by Tamino.

MWP & LIA were clearly important regional climate phenomena. The question to be addresed is how important were they globally? You will find many different reconstructions some of which have regional biasses etc. You will notice that all the good reconstructions, including Mann's Hockey Stick, have error bars. They tend to be llarge for LIA/MWP times because these are a long time ago. I have not seen sensible global rconstructions that have MWP higher temp than now however. Perhaps you can help by posting one.

That does not in any way invalidate Mann's hocket stick work. We could take any one such reconstruction and look at what it is based on, and whether it is likely more or less accurate than Mann. If recent it should be more accurate. Go for it.

Although I doubt you will because you like all believers rely on what the great mann tells you.  Coincidence though that just a couple of years after climate researchers say "we have to get rid of the medeival warm period" Mike Mann produces this POS.

This is a set of ad homs against me + climate scientists. In my case i have posted two substantial links, one of which (Tamino's blog) shows very clearly the concerns about BCP proxies and whether their unreliability undermines Mann's reconstruction. That is if you read the comments, which I am sure you will. Bloig posts, no matter how persuasive, are only seen in context when you have thoughtful (not ad hom style) comments giving contrary views, and equally thoughtful replies to these. You then usually need to go do some reading of source material.

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