Thanks to Willis Eschenbach for the amusing spoof ‘reconstructed’ photo of Michael Mann.
No doubt many blog readers will be familiar with the infamous ‘Hockey Stick’ graph, which used ‘proxy’ reconstructed temperature data up to 1980, grafted onto Hadley CRU instrumental data. The IPCC liked it so much that it appeared several times in the Third Assessment Report of 2001, thus enhancing the man-made global warming scare. A very different graph was used in the 1995 report, which clearly showed a Medieval Warm Period and the Little Ice Age.
To cut a long story short, Steve McIntyre and Ross McKitrick published critiques of the Michael Mann et al ‘Hockey Stick’ in 2003, which were updated in further publications in 2005 (GRL and E&E), followed in 2006 by a presentation to the National Academy of Sciences Expert Panel, “Surface Temperature Reconstructions for the Past 1,000-2,000 Years.”
Steve McIntyre and Ross McKitrick wrote on the Nature blog:
In their summary of the change in consensus over the hockey stick, von Storch and Zorita (VZ) at first did not mention our work, then, in light of criticism, they dismissed our contributions as minimal and largely irrelevant.
We note with some pride that the NAS took a very different and more favorable view of our work, even crediting us with a revival of research on fundamental methodological issues, saying :
“A second area of criticism focuses on statistical validation and robustness. McIntyre and McKitrick (2003, 2005a,b) question the choice and application of statistical methods, notably principal component analysis; the metric used in the validation step of the reconstruction exercise; and the selection of proxies, especially the bristlecone pine data used in some of the original temperature reconstruction studies. These and other criticisms, explored briefly in the remainder of this chapter, raised concerns that led to new research and ongoing efforts to improve how surface temperature reconstructions are performed. (p.110)”
While we are pleased that some of our observations, in particular, about verification statistics and non-robustness, have attracted academic interest (e.g. from Bürger), it was not our intent to develop methodological innovations or tell paleoclimatologists how to do their job.
Our initial objective was simpler: despite the prominence of the MBH98 reconstruction, no one seemed sure how it was done, and nobody had verified the results. Did the reconstruction possess the claimed “statistical skill”? Did it have the claimed “robustness” to the presence/absence of all dendroclimatic indicators? Had the proxies been “rigorously” selected according to objective criteria?
Notwithstanding claims in the MBH papers (e.g. verification r2 skill as shown in MBH98 Figure 3), we showed the answer was, in every case, No. Early segments of the MBH reconstruction fail verification significance tests, a finding later confirmed by Wahl and Ammann and accepted by the NAS Panel. Far from being “robust” to the presence or absence of all dendroclimatic indicators, we showed that results vanished just by removing the controversial bristlecones, a result also confirmed by Wahl and Ammann and noted by the NAS Panel. We showed that the PC method yielded biased trends, an effect confirmed by the NAS and Wegman panels. We showed that pivotal PC1 was not a valid temperature proxy due to non-climatic contamination in the dominant-weighted proxies (bristlecones, foxtails). Here again the NAS panel concurred, saying that strip-bark bristlecones should not be used in climate reconstructions.
The VZ Comment did not refute our research, as we explained in our published Reply and here .
VZ criticize us for supposedly only publishing one peer-reviewed study; however, the IPCC AR4 cites five peer-reviewed studies by us, one of which contains the requested discussion of bristlecones.
While we believe that VZ’s views are unjustified, we believe that they hold them in good faith. Almost uniquely among climate scientists, they have been cordial to us both publicly and privately and we would have no hesitation in requesting either of them as a reviewer. However, we deserve more credit than they give us and we do not agree that their GRL Comment overturned our results.
Steve McIntyre and Ross McKitrick
The NAS Panel said that strip bark trees should be avoided, a policy then disregarded in recent paleoclimate studies (Osborn and Briffa 2006; Hegerl et al 2007; anything by Mann and/or Rutherford; and, of course; Juckes et al 2007).
Now we come to Steve McIntyre’s ‘Little Secret:’
Steve wrote:
Don’t you think that someone on the Team might have been a little curious as to what bristlecone ring widths have done during the past 25 years? For this, we have the classic excuse of Michael Mann and the Team for not updating bristlecone and proxy records is that it’s not practical within the limited climate budgets:
“While paleoclimatologists are attempting to update many important proxy records to the present, this is a costly, and labor-intensive activity, often requiring expensive field campaigns that involve traveling with heavy equipment to difficult-to-reach locations (such as high-elevation or remote polar sites). For historical reasons, many of the important records were obtained in the 1970s and 1980s and have yet to be updated.”
……..I’ve continued to satirize this failure pointing out that several of Graybill’s classic bristlecone sites were easily accessible from UCAR world headquarters in Boulder and that no heroic expedition was required to update, for example, the Graybill sites to the west of Colorado Springs.
To make a long story short, last summer, when my wife and I visited my sister in Colorado Springs……..
…….Prior to the trip, I obtained a permit from the U.S. Forest Service to take dendrochronological samples from bristlecones on Mount Almagre and we did more than look at pretty views; we obtained up-to-date bristlecone samples. I only went up Almagre on the first day. Our permit lasted a month and Pete and Leslie spent two more days on Almagre, finally locating and sampling tagged Graybill trees on the third day.
Before writing this blog piece, I emailed Steve McIntyre. He replied:
“In one sense, it was just testing that needed to be done, and I stated ahead of time that I would archive the results promptly whatever they showed and would archive them when they became available as opposed to when and if I published an academic article on them. Given the reliance both on strip bark bristlecones/foxtails and secondarily on Graybill’s chronologies (although Graumlich’s foxtails are also used), you’d think that even climate scientists would be curious.
I’m not sure that the results can be said to be “unexpected”. However so far they show that (1) there is a “divergence problem” with the bristlecones; (2) more speculatively, supposedly “anomalous” 20th century bristlecone growth may not be due to CO2 fertilization but actually not exist and merely be an artifact of strip bark selection.”
Read more over at Climate Audit where donations can be made via the ‘Tip Jar’ to help Steve cover the costs of this project:
8 Measured Graybill Trees at Almagre
Paul Biggs
21st October 2007
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
““A second area of criticism focuses on statistical validation and robustness. McIntyre and McKitrick (2003, 2005a,b) question the choice and application of statistical methods, notably principal component analysis; the metric used in the validation step of the reconstruction exercise; and the selection of proxies, especially the bristlecone pine data used in some of the original temperature reconstruction studies. These and other criticisms, explored briefly in the remainder of this chapter, raised concerns that led to new research and ongoing efforts to improve how surface temperature reconstructions are performed. (p.110)”
Yes, I think that was one of the minor footnotes in an otherwise lengthy appraisal of the science. They seem to have a grossly inflated sense of their importance on this issue. Further research has confirmed Manns estimation of the past climate.
Even then, the reconstructions are not the major part of the global warming case.
The “Hockey Stick is Dead”, but the “Hockey Stick is Dead Party” is never going to end. Meanwhile, in the real world, climate change is having serious effects on Australia.
“Further research has confirmed Manns estimation of the past climate.”
SJT: Could you post some mainstream references, please? Thanks in advance.
Read the IPCC report.
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch06.pdf
Part 6.
SJT, a bunch of people who have all worked together and who insist recycling many of the SAME proxies including the bristlecones and foxtails in reconstuctions in direct violation of NAS recomendations while using similar flawed methodologies to Mann’s can hardly be called ‘further research’, unless you have your tongue firmly in your cheek.
All the newer papers supporting Mann so far examined fail the same tests as the original hockey stick did.
The fact that peer reviewers have not required these tests to be applied with the results included in the papers before publication is an indictment of published climate science.
Pointing to the IPCC where many of the lead author’s are the same people that produced much of the shoddy science in the first place is not very helpful, as the IPCC is political in both name and process.
Professor Mann looks as if he is trying to sell something. A refrigerator to an Esquimo?
Carl Smith – “SJT, a bunch of people who have all worked together and who insist recycling many of the SAME proxies including the bristlecones and foxtails in reconstuctions in direct violation of NAS recomendations while using similar flawed methodologies to Mann’s can hardly be called ‘further research’, unless you have your tongue firmly in your cheek.”
How do you know this? Are you a researcher in the field? At least one of the studies:
http://www.sciencemag.org/cgi/content/abstract/308/5722/675
“Extracting a Climate Signal from 169 Glacier Records
J. Oerlemans
I constructed a temperature history for different parts of the world from 169 glacier length records. Using a first-order theory of glacier dynamics, I related changes in glacier length to changes in temperature. The derived temperature histories are fully independent of proxy and instrumental data used in earlier reconstructions. Moderate global warming started in the middle of the 19th century. The reconstructed warming in the first half of the 20th century is 0.5 kelvin. This warming was notably coherent over the globe. The warming signals from glaciers at low and high elevations appear to be very similar.”
Does not use any of the previous proxies and comes to a remarkably similar conclusion.
Another:
“Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data
Anders Moberg1, Dmitry M. Sonechkin2, Karin Holmgren3, Nina M. Datsenko2 and Wibjörn Karlén3
1. Department of Meteorology, Stockholm University, SE-106 91 Stockholm, Sweden
2. Dynamical-Stochastical Laboratory, Hydrometeorological Research Centre of Russia, Bolshoy Predtechensky Lane 11/13, Moscow 123 242, Russia
3. Department of Physical Geography and Quaternary Geology, Stockholm University, SE-106 91 Stockholm, Sweden
Correspondence to: Anders Moberg1 Correspondence and requests for materials should be addressed to A.M. (Email: anders.moberg@misu.su.se).
Top of page
A number of reconstructions of millennial-scale climate variability have been carried out in order to understand patterns of natural climate variability, on decade to century timescales, and the role of anthropogenic forcing1, 2, 3, 4, 5, 6, 7, 8. These reconstructions have mainly used tree-ring data and other data sets of annual to decadal resolution. Lake and ocean sediments have a lower time resolution, but provide climate information at multicentennial timescales that may not be captured by tree-ring data9, 10. Here we reconstruct Northern Hemisphere temperatures for the past 2,000 years by combining low-resolution proxies with tree-ring data, using a wavelet transform technique11 to achieve timescale-dependent processing of the data. Our reconstruction shows larger multicentennial variability than most previous multi-proxy reconstructions1, 2, 3, 4, 7, but agrees well with temperatures reconstructed from borehole measurements12 and with temperatures obtained with a general circulation model13, 14. According to our reconstruction, high temperatures—similar to those observed in the twentieth century before 1990—occurred around ad 1000 to 1100, and minimum temperatures that are about 0.7 K below the average of 1961–90 occurred around ad 1600. This large natural variability in the past suggests an important role of natural multicentennial variability that is likely to continue.”
http://www.nature.com/nature/journal/v433/n7026/abs/nature03265.html;jsessionid=637CDFBD11C55C917CFB4A16F8D943F5
does not use PCA analysis.
Perhaps you should take the rantings of MacIntyre with a grain of salt.
Would anyone buy a used car from this Mann?
Ender – “does not use PCA analysis.”
Uses G. Bulloides.
“Ender – “does not use PCA analysis.”
Uses G. Bulloides.”
???????????????????????????????
Meanwhile, in the real world, climate change is having serious effects on Australia.
Posted by: SJT at October 22, 2007 09:46 AM
By ‘climate change’, I assume you mean human induced ‘global warming’.
What unprecedented climate effects on Australia can we attribute to human activity and why?
A type of foraminifera Globigerina bulloides
McIntyre will have inevitably disproved everything of course: http://www.climateaudit.org/?p=848
Of course as chrisgo notes people in the real world are looking for answers. So all this denialist stuff, interesting and combative as it is, doesn’t help anyone trying to make a risk management calculation.
(and you know I can’t do basic maths).
Just more rolling rocks in the road.
Steve McIntyre isn’t a ‘denialist’ in any shape or form. He has pointed out glaring errors in proxy data studies and dodgy data selection. He has come up against vitriol, plus ‘lost’ and withheld or non-archived data. No-one truly interested in objective climate science should defend that sort of behaviour or it’s ‘scientific’ results.
This thread is primarily about how well, or not, tree rings represent measured surface temperatures for the past 25 years.
In all this crap that Luke calls “discussion”..
at no time has he ever presented a solution, (check the archives) ..
in fact he has said there is no solution (check the archives) and also..
never said there is a solution (check the archives)..
Its all just overcompensation from some grievous injury suffered when he was 6..
months old, about the time you start to wean these…
suckers
Well yes I did actually Rog & Pat – CHECK THE ARCHIVES – but you said like the tossed up little Taliban-like wanker that you are – “too much info” you said. Rog – “whatever a primordial scum like critter a Rog is” – go do some felching over at Tim Blair – it’s your style.
Don’t be so unkind to rog, Luke.
He probably doesn’t realize this is your blog.
No f*ck him – Rog have been an arsehole from way back.
Fuc*ing and ar*seholes, I’ll leave to you.
have been, has been – Luke is too tense, or two tents.
And now I’m like a Taliban, is that a curse? – I’ll check the archives but I think that is a new one.
Very good Luke, you are breaking your own records
Rog
Luke comes up with copious amounts of science, which just happens to be mostly ignored, despite the time it must take him to read and collate it for posting here. In the meantime, the likes of Rog and Ian blithely let it pass over their heads with no meaningful responses at all.
Nah I was just kidding … Rog is a cool guy for an etymologist, but I did have to break out my backup monitor after I punched the last one out. Phil wasn’t using it anyway.
As I was about to say, and relevant to the lead post after Ender, and I AM NOT SHOUTING, is that Tamino has made an interesting comparison the Medieval Optimum temperature pattern the current temperature rise using Moberg (which I’m sure Paul can provide a McIntrye reference as to why it’s crap). Basically it’s steeper.
http://tamino.wordpress.com/2007/10/19/not-alike/
It’s also worth noting the Medieval Optimum wasn’t that optimum in places other than Europe with prolonged droughts in the USA.
http://en.wikipedia.org/wiki/Medieval_Warm_Period
Anyway Tamino makes a case for the current warming being exceptional.
C’mon SJT, are you Lukes therapist?
When it comes to copious, Lukes got in bucketfuls. But without meaningful analysis it aint worth a hill of beans, just online masturbation.
I doubt that Moberg would have any basis for claiming his reconstruction was perfect. Science is supposed to be critical – it’s not about protecting flawed data and methodology. McIntyre’s criticism is referenced and valid:
http://www.climateaudit.org/?p=848
Luke likes to derive certainty from uncertainty.
I doubt that proxy data is as reliable as a thermometer free of non-climatic influences. No-one knows how warm the MWP was for sure, plus regional differences existed then, as now.
What’s striking about the hockey stick is the large error bars for the proxy data, and the fact that instrumental data was grafted on to proxy data.
Since when has anonymous Tamino been an authority on anything? Who wrote the Wiki article?
Come on Paul – no dummy spits – I provided as is. Do I really have to get the USA drought papers out?
And while we’re on Tamino his return serve on Svensmark and Friis-Christensen is most excellent. Thanks for reminding me.
http://tamino.wordpress.com/2007/10/21/how-to-fool-yourself/#more-440
Just another day of denialist busting.
Actually Rog & Pat is getting better – we’re not at multiple lines – an attempt at discussion. Typically it’s the sneering one liner from a fascist Tim Blair devotee with no stake in the climate issue.
Luke – use the papers to keep yor french fries warm.
What is the ‘Hockey Stick’ Debate About?
http://www.climatechangeissues.com/files/PDF/conf05mckitrick.pdf
What does Figure 7 of MBH’98 tell us about solar?
http://www.climateaudit.org/?p=692
As for cosmic rays on long timescales, Shaviv’s work (2003) on the earth’s passage through spiral galaxies was confirmed independently in 2005. It is not unreasonable to hypothesise that there would also be an effect on shorter timescales via a similar mechanism.
As for solar activity, it has been the dominant driving force since the LIA, and peaked in the 20th century – it’s now on the way down – Even L & F 2007 say:
Nevertheless, it is possible that the decline seen since 1985 marks the beginning of the end of the recent grand maximum in solar activity and the cosmogenic isotope record suggests that even if the present decline is interrupted in the near future, mean values will decline over the next century. This would reduce the solar forcing of climate, but to what extent this might counteract the effect of anthropogenic warming, if at all, is certainly not yet known. For this reason, studies of putative amplification of solar forcing over the past 150 years (Stott et al. 2003) are likely to be important for understanding future changes.
The sun’s going down, and temperature is going with it – hence 1998 remains the record instrumental global average temperature. ARGO says little or no ocean warming for the past 5 years.
Davey Gam Esq.- If you can pull Mann-Made global warming out of “Extracting a Climate Signal from 169 Glacier Records” you must be reading between the lines. The published record only extends back to the 1700s (some what earlier with the stated lag time). IMHO this paper documents first, the end of the LIA and second, the fact that Mann’s omission of the magnitude of the LIA on his hockey stick graph was an error. The fact that global temperatures are warmer now than 100 years ago is well documented. What is not well documented is (Natural-Human= ?).
Davey, I am sorry, my post above should have been directed to Ender’s post, not yours.
Davey Gam Esq-
The Oerlemans publication you cite mentions warming beginning in the mid 1800s and a quantity of 0.5 K warming from 1900-1950. This is prior to substantial contributions of man-made GHGs to the atmosphere. Even the IPCC doesn’t attempt to explain the warming during these periods as anthropogenic.
The Moberg publication says temps were as warm during the MWP as the late 20th century. And the last line: “This large natural variability in the past suggests an important role of natural multicentennial variability that is likely to continue.”
You’ve cited two papers which suggest today’s temps are not extraordinary and significantly the product of natural climate swings.
Oops.
Maybe solar is on the way down or maybe it’s a bit o’ the old internal variability.
Do we have some actual data that say solar radiation is declining?
Ocean surprises – maybe not!
Proc Natl Acad Sci U S A. 2007 June 26; 104(26): 10768–10773.
Simulated and observed variability in ocean temperature and heat content
K. M. AchutaRao,*† M. Ishii,‡ B. D. Santer,* P. J. Gleckler,* K. E. Taylor,* T. P. Barnett,§ D. W. Pierce,§ R. J. Stouffer,¶ and T. M. L. Wigley‖
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1904169
Observations show both a pronounced increase in ocean heat content (OHC) over the second half of the 20th century and substantial OHC variability on interannual-to-decadal time scales. Although climate models are able to simulate overall changes in OHC, they are generally thought to underestimate the amplitude of OHC variability. Using simulations of 20th century climate performed with 13 numerical models, we demonstrate that the apparent discrepancy between modeled and observed variability is largely explained by accounting for changes in observational coverage and instrumentation and by including the effects of volcanic eruptions. Our work does not support the recent claim that the 0- to 700-m layer of the global ocean experienced a substantial OHC decrease over the 2003 to 2005 time period. We show that the 2003–2005 cooling is largely an artifact of a systematic change in the observing system, with the deployment of Argo floats reducing a warm bias in the original observing system.
Paul Biggs – “The sun’s going down, and temperature is going with it – hence 1998 remains the record instrumental global average temperature. ARGO says little or no ocean warming for the past 5 years.”
So where is the graph showing that the long term temperature trend is downward? What is the magnitude the solar forcing? Reference please. Where is the study that shows solar forcing is sufficient to account for recent temperature rises? Reference please.
ARGO released a new flood of information where before it was very thin on the ground (or sea if you prefer). Only the stupidist see this as evidence of no warming.
Thanks Michael,
What was that all about? Seriously though, I have an important announcement. Poor Luke passed away yesterday from Galloping Coprolalia, combined with advanced von Munchausen Syndrome. SJT and I, as fellow greens, were there at the last. Between bouts of faecal delirium, Luke asked for forgiveness from Motty and Rog for his obscenities. It was just the disorder talking.
I have heard that there is a fake Luke now posting. This is a cunning conspiracy by oil and tobacco companies. The new, fake Luke, will write ever more outrageous babble, so trying to discredit us greens. Readers should be alert to this ploy.
SJT has declined to post any more, as a sign of respect to the late Luke, but those oil and tobacco companies (probably coal and nuclear too) may put up a bogus SJT. Is there no end to their cunning? Beware! Be alert, but not alarmed. We greens will triumph eventually. (Fridge stickers will follow.)
P.S. Thinks – is Michael Mann a greeny or an Exxon agent provocateur? Perhaps something else?
The problem with tree ring analysis is that it is assumed that a wide ring is the product of warmer temperature and higher rainfall. This can be the case in some instances but it is not certain enough to rely on.
The widest rings usually indicate a good growing season which is not a synonym for high rainfall and high temperatures. The best growing seasons usually have more moderate temperatures and only slightly above average rainfall. What distinguishes them is consistent rainfall that enables continuous growth.
The highest (1st decile) rainfall years almost always have high intensity events followed by periods of moisture deficit. Ditto for warmer years which seem to coincide with lowest decile rainfall years and periods of moisture stress and less than ideal growth.
The variability within these elements are sufficient to make these tree ring records very unreliable. They are a measure of seasonal quality, not temperature or rainfall.
SJT accuses me of not making material contributions? Go to the far queue, punk.
Another scintillating expose of content and comprehensive addition to the debate from now pseudo Davey Gam (aka fence-sitter in disguise, norty personage and rapscallion). Incidentally Davey I have never seen you once pounce on Mottsa for having a go. (I wonder why that is – double standards – of course not). As I said Davey – I AM NOT SHOUTING ! OK !
Anyway lah de dah and back to it – Ian’s being nice so – so far so good. Moberg’s paper brought up be Ender is using other proxies than tree rings.
Ender – The IPCC classify the ‘Level of Scientific Understanding’ for ‘Solar Irradiance’ as ‘Low.’ As L&F pointed out, there is an unknown amplification factor.
Which part of 1998 being the record year and now being 2007 don’t you understand. The falling temperature graph will be drawn during solar cycles 24 and 25, if I’m right. There are obviously other factors to consider, but solar forcing is heading for a fall.
A recent (Solanki) reconstructed increase in solar irradiance since 1700 is around 1.4Wm-2.
Pseudo ‘Luke’,
Stop desecrating the memory of our fallen comrade, Lucius Gluteus Maximus.
Paul, you just don’t understand. Anthony explained it all to me. Apparently we have to get over the whole 1998 was the hottest year thingy to fully understand global warming.
SJT, as already pointed out by others, the glacier reconstruction is a short term joke in the context of backing up Mann and other multi-century or longer ‘hockey sticks’, and the Moberg paper using wavelets instead of PCA has far greater variability than Mann and other ‘hockey sticks’.
Of course, any study using tree rings or other biological proxies still has to sort out the upside-down quadratic response of living organisms to environmental factors before being anywhere near credible!
For those who do not understand what I’m getting at, each environmental factor (temperature, moisture, light, nutrients, etc.) has an optimal quantity for maximum growth, and less or more of each slows growth, which may be plotted on a graph as an upside down ‘U’ shaped curve.
All these environmental factors confound each other – is that tree ring narrow because it was too hot or too cold and/or too wet or too dry and/or too sunny or too cloudy or ….?
See this graph for the optimal temperature case for bristlecones:
http://i173.photobucket.com/albums/w45/CarlSmith_2007/climate/growth_vs_temp.gif
IPCC AR4 and the Return of Chucky – He’s Baaack!
http://www.climateaudit.org/?p=2245