NOTE: This has been running two weeks at the top of WUWT, discussion has slowed, so I’m placing it back in regular que. – Anthony
UPDATES:
Statistician William Briggs weighs in here
Eduardo Zorita weighs in here
Anonymous blogger “Deep Climate” weighs in with what he/she calls a “deeply flawed study” here
After a week of being “preoccupied” Real Climate finally breaks radio silence here. It appears to be a prelude to a dismissal with a “wave of the hand”
Supplementary Info now available: All data and code used in this paper are available at the Annals of Applied Statistics supplementary materials website:
http://www.imstat.org/aoas/supplements/default.htm
=========================================
Sticky Wicket – phrase, meaning: “A difficult situation”.
Oh, my. There is a new and important study on temperature proxy reconstructions (McShane and Wyner 2010) submitted into the Annals of Applied Statistics and is listed to be published in the next issue. According to Steve McIntyre, this is one of the “top statistical journals”. This paper is a direct and serious rebuttal to the proxy reconstructions of Mann. It seems watertight on the surface, because instead of trying to attack the proxy data quality issues, they assumed the proxy data was accurate for their purpose, then created a bayesian backcast method. Then, using the proxy data, they demonstrate it fails to reproduce the sharp 20th century uptick.
Now, there’s a new look to the familiar “hockey stick”.
Before:
After:
Not only are the results stunning, but the paper is highly readable, written in a sensible style that most laymen can absorb, even if they don’t understand some of the finer points of bayesian and loess filters, or principal components. Not only that, this paper is a confirmation of McIntyre and McKitrick’s work, with a strong nod to Wegman. I highly recommend reading this and distributing this story widely.
Here’s the submitted paper:
(PDF, 2.5 MB. Backup download available here: McShane and Wyner 2010 )
It states in its abstract:
We find that the proxies do not predict temperature significantly better than random series generated independently of temperature. Furthermore, various model specifications that perform similarly at predicting temperature produce extremely different historical backcasts. Finally, the proxies seem unable to forecast the high levels of and sharp run-up in temperature in the 1990s either in-sample or from contiguous holdout blocks, thus casting doubt on their ability to predict such phenomena if in fact they occurred several hundred years ago.
Here are some excerpts from the paper (emphasis in paragraphs mine):
This one shows that M&M hit the mark, because it is independent validation:
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. While the Lasso generated reconstructions using the proxies are highly statistically significant compared to simple null models, they do not achieve statistical significance against sophisticated null models.
We are not the first to observe this effect. It was shown, in McIntyre
and McKitrick (2005a,c), that random sequences with complex local dependence
structures can predict temperatures. Their approach has been
roundly dismissed in the climate science literature:
To generate ”random” noise series, MM05c apply the full autoregressive structure of the real world proxy series. In this way, they in fact train their stochastic engine with significant (if not dominant) low frequency climate signal rather than purely non-climatic noise and its persistence. [Emphasis in original]
Ammann and Wahl (2007)
…
On the power of the proxy data to actually detect climate change:
This is disturbing: if a model cannot predict the occurrence of a sharp run-up in an out-of-sample block which is contiguous with the insample training set, then it seems highly unlikely that it has power to detect such levels or run-ups in the more distant past. It is even more discouraging when one recalls Figure 15: the model cannot capture the sharp run-up even in-sample. In sum, these results suggest that the ninety-three sequences that comprise the 1,000 year old proxy record simply lack power to detect a sharp increase in temperature. See Footnote 12
Footnote 12:
On the other hand, perhaps our model is unable to detect the high level of and sharp run-up in recent temperatures because anthropogenic factors have, for example, caused a regime change in the relation between temperatures and proxies. While this is certainly a consistent line of reasoning, it is also fraught with peril for, once one admits the possibility of regime changes in the instrumental period, it raises the question of whether such changes exist elsewhere over the past 1,000 years. Furthermore, it implies that up to half of the already short instrumental record is corrupted by anthropogenic factors, thus undermining paleoclimatology as a statistical enterprise.
…
We plot the in-sample portion of this backcast (1850-1998 AD) in Figure 15. Not surprisingly, the model tracks CRU reasonably well because it is in-sample. However, despite the fact that the backcast is both in-sample and initialized with the high true temperatures from 1999 AD and 2000 AD, it still cannot capture either the high level of or the sharp run-up in temperatures of the 1990s. It is substantially biased low. That the model cannot capture run-up even in-sample does not portend well for its ability
to capture similar levels and run-ups if they exist out-of-sample.
…
Conclusion.
Research on multi-proxy temperature reconstructions of the earth’s temperature is now entering its second decade. While the literature is large, there has been very little collaboration with universitylevel, professional statisticians (Wegman et al., 2006; Wegman, 2006). Our paper is an effort to apply some modern statistical methods to these problems. While our results agree with the climate scientists findings in some
respects, our methods of estimating model uncertainty and accuracy are in sharp disagreement.
On the one hand, 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. The fundamental problem is that there is a limited amount of proxy data which dates back to 1000 AD; what is available is weakly predictive of global annual temperature. Our backcasting methods, which track quite closely the methods applied most recently in Mann (2008) to the same data, are unable to catch the sharp run up in temperatures recorded in the 1990s, even in-sample.
As can be seen in Figure 15, our estimate of the run up in temperature in the 1990s has
a much smaller slope than the actual temperature series. Furthermore, the lower frame of Figure 18 clearly reveals that the proxy model is not at all able to track the high gradient segment. Consequently, the long flat handle of the hockey stick is best understood to be a feature of regression and less a reflection of our knowledge of the truth. Nevertheless, the temperatures of the last few decades have been relatively warm compared to many of the thousand year temperature curves sampled from the posterior distribution of our model.
Our main contribution is our efforts to seriously grapple with the uncertainty involved in paleoclimatological reconstructions. Regression of high dimensional time series is always a complex problem with many traps. In our case, the particular challenges include (i) a short sequence of training data, (ii) more predictors than observations, (iii) a very weak signal, and (iv) response and predictor variables which are both strongly autocorrelated.
The final point is particularly troublesome: since the data is not easily modeled by a simple autoregressive process it follows that the number of truly independent observations (i.e., the effective sample size) may be just too small for accurate reconstruction.
Climate scientists have greatly underestimated the uncertainty of proxy based reconstructions and hence have been overconfident in their models. We have shown that time dependence in the temperature series is sufficiently strong to permit complex sequences of random numbers to forecast out-of-sample reasonably well fairly frequently (see, for example, Figure 9). Furthermore, even proxy based models with approximately the same amount of reconstructive skill (Figures 11,12, and 13), produce strikingly dissimilar historical backcasts: some of these look like hockey sticks but most do not (Figure 14).
Natural climate variability is not well understood and is probably quite large. It is not clear that the proxies currently used to predict temperature are even predictive of it at the scale of several decades let alone over many centuries. Nonetheless, paleoclimatoligical reconstructions constitute only one source of evidence in the AGW debate. Our work stands entirely on the shoulders of those environmental scientists who labored untold years to assemble the vast network of natural proxies. Although we assume the reliability of their data for our purposes here, there still remains a considerable number of outstanding questions that can only be answered with a free and open inquiry and a great deal of replication.
===============================================================
Commenters on WUWT report that Tamino and Romm are deleting comments even mentioning this paper on their blog comment forum. Their refusal to even acknowledge it tells you it has squarely hit the target, and the fat lady has sung – loudly.
(h/t to WUWT reader “thechuckr”)
Barry,
Even IF those classroom results are valid, it is and incredibly huge stretch to then declare that all us humans have to do is is control the level of .03% of the atmosphere to set the temperature of the earth (as though CO2 were some magical thermostat). There are so many known and unknown (and please don’t be foolish enough to ask me to prove we don’t know something) factors and interactions in the earth’s climate, that it is beyond foolhardy to pin everything on TRYING to control the reletavie level of CO2 in the earth’s atmosphere (unless, of course, you personally are going to make money from others doing so).
One only has to point to China where they say they believe in AGW (to get all that income from selling carbon credits), but then are adding hundreds of coal fired power plants to their electrical grid to show just why there are so many pushing this stupid idea.
It even makes me wonder if you are making money throught the promotion of this concept or potentially could make a lot of money through its acceptance.
Finally, the GCMs have yet to accurately predict the earth’s climate. Until they do, I, for one, will not accept the “magic” of CO2
from Barry:
“Lab tests performed thousands of times in high schools and universities definitively show that increasing CO2 in a volume of atmosphere will result in more infrared absorption leading to the heating of the volume.”
Yes, this is where the misconception starts, as the other part of this lab test is missing. Namely that since CO2 is an IR active gas, it also cools an atmospheric volume quicker as the relative volume of CO2 increases.
The other part of the lab test is to take a volume of gas with CO2 at a temperature greater than ambient and observe its rate of cooling. More CO2 = more cooling.
The relevance to the climate in this simple model, is the net effect that the 0.038% of CO2 in the atmosphere has between its small daytime heating effect and the small night-time cooling effect.
Oh, and the schools should also point out that CO2 is about 25 times less prevalent that H2O, which is a more IR active gas.
I’ve read all the comments so far. Good inputs, very informative as usual.
Some unbelievably smug MIT physicist made me quite nauseous though. Surreal.
For Barry and all those debating with him. Please read my presentation of a statistical model, http://www.kidswincom.net/CO2OLR.pdf and see where it fits in your debate over physics and model validity.
Henry@ur momisuglybarry
If you had understood all my postings here on this thread you would have figured out that I think the basic science is completely wrong – i.e. unsubstantiated by any real experiments and testing. No correct formulae. What the IPPC did is put the horse behind the carriage. They assumed they knew what the cause was of global warming i.e. GHG’s – and CO2 specifically. Then by weighting the concentrations (back to 1750) they made their assumptions and theories. This is the worst mistake a scientist can make: assuming you know the cause of a problem and then trying to work your way back to find a solution for the problem. I know this! ! But now it is slowly dawning on all of them that CO2 might not be the problem.
As for me: I have come to a point where I am doubting that we really have a problem.
It seems to me earth has its own cooling system.
http://wattsupwiththat.com/2010/07/24/willis-publishes-his-thermostat-hypothesis-paper/
have a nice weekend you all! enjoy lobal warming while we can~!! take a dip!!@ur momisugly!
What was that story of 3 persons :
EVERYBODY thought that SOMEBODY would do it (the experiments, the tests, the measurements ) and in the end NOBODY did it.
I tried posting the following at Deep Climate this Friday afternoon:
“R.S.Brown | August 20, 2010 at 1:33 pm | Reply Your comment is awaiting moderation.
Since Mann et alia have yet to release their early statistical methodologies in a coherant
format, even with the Mann et al (2004) Corrigendum to MBH98, it’s tough to have
much faith in their follow up statistical work(s).”
It will be my first time posting a comment there.
@duckster
‘Since when has it been science to accept a paper as scientifically valid without its findings being independently repeated?’
I was under the impression that this is the norm for climatological work. Since data and methods are rarely published in enough detail, independent repeats are, by definition, impossible.
orkneygal says:
August 17, 2010 at 6:14 pm
“For example, it might have been hotter in 1066.”
Yes, I think Magnus Barefoot would agree.Even though he was a bit later.
Isnt it funny that he was “King of Mann and the Isles” ? (Is it a typo?)
Here;
http://en.wikipedia.org/wiki/Magnus_III_of_Norway
barry says:
August 20, 2010 at 8:30 am
stephen richrds,
Barry says:
basic physics tells us that CO2 will cause temps to rise
Henry you are correct when you say that NO definitive study has ever been done which proves beyond doubt that CO² warms the planet
Firstly, there is no such thing as a definitive paper. Were Einstein’s relativity papers ‘definitive?’
Wrong as usual. Physics models are always defined within the limits at which they match reality. When eistein proposed both his theory of relativity and his special theory of relativity he proposed them from a theoretical point of view and provided the equations on which his proposition was based. Much of significance of his theories have only recently been understood (galaxy lensing) but the fundamentals were shown to be valid by the construction of the atomic weapons of WWII and the nuclear piles before that. Einsteins theories WERE DEFINITIVE in every way but were shown not to describe some molecular features at the limit after further research. Hence the development of Quantum mechanics (so called because Einstein and his colleagues decided it wasn’t true Physics. Now we have other theories such as string because the quantum model has been shown not to describe all the features of the atomic world as exposed by higher and higher energy colliders.
So I repeat, let’s see your CO² model equations working with reality at the molecular and atmospheric level. I have seen this excuse too much from you Climate cowboys. It’s time you lot understood what REAL SCIENCE is.
Basic physics tells us that the CO² molecule absorbs IR at very specific and narrow bands. Some of those bands absorb at energies re-radiated by the planet. It also says that all excited atoms always want to be at their ground state and will try to get their as soon as possible. Probability functions for determining the mean time to rest are available from all good basic physics books. I suggest you read one.
Stephen Richards BSc MSC Solid State Physics and Material Physics.
Latimer Alder says:
August 20, 2010 at 12:25 pm
@duckster
‘Since when has it been science to accept a paper as scientifically valid without its findings being independently repeated?’
I was under the impression that this is the norm for climatological work. Since data and methods are rarely published in enough detail, independent repeats are, by definition, impossible.
Duckster. Foot, Mouth swallowed comes to mind.
Those stupid school test drive me to distraction. I have threatened to sue my granddaughters school if they do it.
Let me explain. Glass bowl filled with wet air. Light bulb close by. Heats glass which transfers energy both by radiation from the bulb (energy unknown) and kinetic from the glass. Gas is trapped convection occurs for a few seconds or minutes until some sort of equilibrium arrives. Temp appears higher in one glass than the other. Relation to planet Earth ZERO, NONE, AUCUNE, DE NADA.
barry,
your discussion of experiments with CO2 in glass tubes is something of a strawman. Sceptics accept that the gas absorbs ir, but the real question is what is the aggregate effect in the real world climate with all the hydrological and convection cycles. Even these flask experiments lead to a very limited temperature sensitivity to co2 – about 1.2c per doubling. Some are arguing for a net negative feedback and some for positive. Those who say we do not know the answers to these questions are correct, and those who say otherwise are charlatans.
barry wrote:
“Lab tests performed thousands of times in high schools and universities definitively show that increasing CO2 in a volume of atmosphere will result in more infrared absorption leading to the heating of the volume.”
Not quite. CO2 alone is not enough to alone achieve the rise in global temperature predicted by the IPCC. A positive feedback between CO2 and water vapour is assumed in the GCM simulation models. In reality, not only the magnitude but also the sign [positive or negative] of such a hypothesized feedback mechanism is unknown.
Note that water vapour, by far the most common greenhouse gas and the one responsible for making our planet inhabitable, is only treated as a secondary effect. Also the role of clouds, especially their role in feedback mechanism, is ignored.
Seitz is so saucy;
Barry’s been into the lab.
Show me the real world.
==============
Anonymous blogger “Deep Climate” weighs in with what he/she calls a “deeply flawed study” here:
http://deepclimate.org/2010/08/19/mcshane-and-wyner-2010/
Romm of course republishes it, since he’s not competent to “eviscerate” it himself.
Still nothing from Real Climate.
“”” barry says:
August 20, 2010 at 8:30 am
stephen richrds
Barry says:
basic physics tells us that CO2 will cause temps to rise
Henry you are correct when you say that NO definitive study has ever been done which proves beyond doubt that CO² warms the planet
Firstly, there is no such thing as a definitive paper. Were Einstein’s relativity papers ‘definitive?’
Lab tests performed thousands of times in high schools and universities definitively show that increasing CO2 in a volume of atmosphere will result in more infrared absorption leading to the heating of the volume. “”””
Not sure who said what up there particularly this:- “””””
Lab tests performed thousands of times in high schools and universities definitively show that increasing CO2 in a volume of atmosphere will result in more infrared absorption leading to the heating of the volume. “””””
Now that is patent nonsense; well about the experiment being performed thousands of times in schools and universities. I’d be very surprised if Barry; whoever Barry is can cite just ONE specific instance in which that experiment was performed.
Shall I explain? Well of course. The postulate is that CO2 in the atmosphere captures LWIR Radiation emitted from the surface and “heats” the atmosphere; and that experiment has been performed thousands of times in schools and universities.
Well no it actually hasn’t. What has been done in schools and universities and even on TV shows like myth busters and the like is to take two samples of air; one with more CO2 than the other; but likely neither one having the same trace amount of CO2 that exists in the real atmosphere; and the other say double that; and then those two totally phony air samples; both of which have probably been shorn of any water vapor; unlike the real atmosphere; and then instead of irradiating these two phony air samples with LWIR radiation corresponding to that typically emitted by the average earth surface which would approximate a Black body radiator at about 288 Kelvins or +15 deg C or so and having a spectrum from about 5 microns to 80 microns, which includes the active 15 micorn CO2 band; they choose to use a very high temperature “heat lamp” or even a hotter light bulb that could be 2700 Kelvins or so, and which emits radiation in the visible and near IR region; none of which is emitted from a 288 K black body in any measureable amount.
So to actually perform the demonstrative experiment; you need one sample of air with say 390 ppm of CO2 and the other say 780 ppm of CO2; and I’ll even accept the total exclusion of any H2O from both samples.
And then you need to place some sort of brick or other dark object that is at a temperature of about 15 deg C (59 deg F) in front of the samples to emit the necessary thermal radiation spectrum to match what actually happens in the real atmosphere; except of course the real atmosphere is NEVER devoid of more H2O vapor than it has CO2.
so NO Barry, the experiment has not been performed thousands of times in schools and laboratories; possibly not even once.
And for the legal disclaimer; I fully accept the fact that trace amounts of CO2 in the atmosphere DO intercept some of the LWIR radiation emitted from the earth’s surface, and warms the atmosphere; but the effect has seldom if ever been tested in a laboratory setting.
Barry says:
August 20, 2010 at 8:30 am
stephen richrds,
Barry says:
basic physics tells us that CO2 will cause temps to rise
Henry you are correct when you say that NO definitive study has ever been done which proves beyond doubt that CO² warms the planet
Firstly, there is no such thing as a definitive paper. Were Einstein’s relativity papers ‘definitive?’
Lab tests performed thousands of times in high schools and universities definitively show that increasing CO2 in a volume of atmosphere will result in more infrared absorption leading to the heating of the volume. “”””
I couldn’t get past the horrible grammar in the first paragraph of the Eduardo Zorita paper to care.
REPLY: English is not his native language, cut some slack. – Anthony
Anthony Watts says:
August 20, 2010 at 2:24 pm
“Anonymous blogger “Deep Climate” weighs in with what he/she calls a “deeply flawed study” here:……”
DC spends a considerable amount of time, (about half of the response) taking issue on the background of the paper. None of the background has anything to do with the validity of the study. DC does take time to take issue with the methodologies used in sect 3 of the paper, but it comes down to “the paper is wrong because I don’t agree with the results and they should have done x to get the results I would like to see.”
Eviscerate seems to be an extreme description of the critique. It may have been more believable if DC hadn’t try to make a points playing to their crowd, “Similarly, the review of the “scientific literature” relies inordinately on grey literature such as Steve McIntyre and Ross McKitrick’s two Environment and Energy articles and the (non peer-reviewed) Wegman report.”
I asked how they thought that might be relevant, but it seems they just don’t believe mention M&M or the Wegman report should be allowed. “Why should that be permissable?” <———- quote from DC. Finally, after pressing, DC states this, “There is a difference between describing or assessing the grey litarature and *relying* on it. On every issue M&W side with M&M and Wegman.
The statistical analysis is flawed because it does not implement robust methodologies.”
Bold emphasis is mine.
Huh? I read the background section as a chronicle of studies and the subsequent discussions. And I suppose the chronology could be a bit off as DC states, but “siding with M&M and Wegman during the background invalidates the study? Since when? The study doesn’t rely on M&M nor Wegman. In fact, one could take all references to both and the study would remain the same. After that statement, I saw no reason to continue dialogue there.
I’m a bit underwhelmed with the critique. But it could be my emotional response to the word “robust”.
I’ve had enough talk. It is now 9AM here on the East coast of Australia, and I am off to vote in our elections. Hopefully, this evening, we will have a new government and I remember Tony Abbot saying, “Climate change is crap”.
I hadn’t entertained the possibility that deepclimate be a ‘she’.
Barry
Your post at August 20, 2010 at 7:34 am is not acceptable.
You quote me at August 20, 2010 at 2:14 am stressing:
“THE SKEWING – NOT THE USE OF PCA – IS THE FLAWED METHODOLOGY INTRODUCED BY THE ‘TEAM’.”
and respond with
“The various studies use different methodologies. You’ve retreated from PCA calibration to some ambiguous ‘skewing’.”.
NO!
That is NOT a retreat. It is a stressing of my point at August 19, 2010 at 1:20 pm
that you tried to ignore.
I had then said (in full);
“Barry:
At August 19, 2010 at 9:25 am you ask me:
“Please name the the “flawed statistical analysis method” common to the studies listed. Acronyms or short-hand will do.”
Sorry, I assumed you knew since you have displayed such confidence in it (above).
The “flawed statistical analysis method” is to use Principle Component Analysis (or PCA) that applies principal components in a ”skew”-centered fashion such that they are centered by the mean of the proxy data over the instrumental period.
This method was novel to Mann et al. in MBH98. Standard PCA analysis centers by the mean of the entire data record.
But the self-termed ‘hockey team’ are dedicated followers of fashion so they all adopted Mann’s novel method.
And the Mann-’skew’ induces PCA to generate ‘hockey sticks’.
Richard”
So, my saying,
“THE SKEWING – NOT THE USE OF PCA – IS THE FLAWED METHODOLOGY INTRODUCED BY THE ‘TEAM’.”
is NOT “a retreat” from my having said,
“And the Mann-’skew’ induces PCA to generate ‘hockey sticks’ ”.
It is a shouting of the same statement.
If you do not like a fact then that is no reason for you to pretend that I did not state the fact and – on the basis of that pretence – to falsely assert that I have “retreated” from stating that fact.
Richard
REPLY: Do you treat all members of the public with such a condescending attitude? And academics wonder why the public does not take them seriously when they try to communicate AGW ideas. You are exhibiting the same sort of attitude as Phil Jones and the team. – Anthony
One tries to be equitable, but when one side actually does science day in and day out and the other divides its time between riding a one stick pony and trolling the literature for dead horses to beat , the comedy of manners of some scientists behaving badly some of the time cannot long prevail over the hilarity of seeing bad science obtusely discussed
You distort. We deride.
REPLY: Ah, well Mr. Sietz, I daresay, there will come a day, when that holier than thou viewpoint of yours will have a shift in equity. In the meantime you might consider doing some science to contribute to this thread, you are even welcome to run a guest post on your “tiny bubbles” theory. Since you are foaming here, it seems only appropriate that you follow up to our first coverage of it. Let me know if you’d like to do a guest post. – Anthony Watts
The authors have done a really excellent job in showing what the data really contain. But unfortunately I still have to do some nitpicking. 1998 of all years is not a year to base statistics on: it is an outlier, the year of the super El Nino that does not even belong to the ENSO system that dominates temperature history. Secondly, I think it is simply stupid to change scale when you are trying to compare curves. The scale of the second graph is reduced by a factor of two from first one. The difference would be much more dramatic if you used the same vertical scale for both curves. And my personal feeling is that putting an uncertainty estimate on the graph as they all do is simply an annoyance and does not contribute any real information. That is because neighboring points are strongly correlated and the statistics used clearly fail to take this into account.
M&M and M&W were not able to reproduce Mann’s results.
Has anyone tried to jiggle with it to try and get the same results that Mann did?