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”)
Hmmm….methinks “Mike” Roddy is the alter ego of Mike Mann….
Richy, I’d like to ask you yourself to be a bit more scientific yourself, before you wonder about others. Scientific Method has to do with, first of all, paying close attention. So – Have you noticed that many readers here have clearly READ the paper, for starters? Have you noticed how many are drawing on the paper for their remarks here? Have you considered how such remarks imply having done earlier homework and research, too? Have you simply allowed for the fullness of human nature, that, when the careful analysis has been done, still needs to shout whooppee or c**p? Have you considered the function of WUWT and how it dovetails into, and balances, the function of Climate Audit? Have you looked at the CA thread for more careful scientific analysis? Have you considered that many posters here also post there? And if these remarks of mine look vague and “unscientific” to you, just click my name. Think for yourself. Here we don’t expect to be spoonfed with “scientific results”, we want to understand the science for ourselves, and one consequence of this is, we need to include not only all the counter-arguments but also something of all the facets of our humanity, if we are really to know in the depth of our beings that the science is being done. This might look messier than RealClimate but we know our science is real because it does not involve suppression.
@Gail Combs
Thanks. I have read the paper now. I understand what it is about. On face value, it looks really good – a very solid piece of research. I also think that it will be 4 – 5 years before we can objectively evaluate whether the paper is successful in doing what it claims to be doing. Mann et al need a chance to respond. It’s way too premature to be claiming that the Hockey Stick is dead in the water.
@warren in Minnesota
Once again – the timing of the MWP, if you accept the M&W graph above, wildly conflicts with the timing of the MWP graphs that have commonly been used here – cited earlier – which clearly placed the MWP at 1200 – 1400ce. I could use this paper to therefore discredit many of the lines of argument that have been made here in support of a medieval warming period (it almost completely disappears into the margin error, temporal placement wildly inconsistent etc.). Not that I am doing this. My point is that this paper also undermines much of the work that has been ‘published’ here.
@Jaye
Actually not. For the purposes of rejecting a hypothesis all “we” need is one counter example.
But if you are using an argument that conflicts with previous arguments that you have used to discredit CAGW, then that’s not science. What it amounts to is the logical fallacy of Logical Inconsistency. What I just don’t get is why no-one here thinks that this paper doesn’t also call into question many of the models and arguments and theories that have been flying around here for the past couple of years.
Rather than cheering the death of the hockey stick (‘Gotcha’ Science), you should be using the paper to re-evaluate all the arguments you have made that might be affected by the paper. That would at least make your process scientific, even if it didn’t lead to the generation of a new theory.
intrepid_wanders says:
August 15, 2010 at 9:25 pm
Just because O.J. Simpson was found innocent in the criminal case, does that force you to understand that he did not kill his ex-wife? That is why politics need to stay out of science. ))
The reason we are here and the world is being dragged into ruin is because immoral Political Activists are using twisted science as a social engineering tool. Politicains using like minded lackeys as a Higher Authority.
regards
duckster says:
August 14, 2010 at 7:48 pm
No I don’t need a theory to explain what is happening now when pointing out a error in your theory.
For example, let’s say the local veterinary society announces the theory that storks are responsible for the appearance of human babies. They are doing this hoping we will all agree to raise taxes to pay for a bird care facility in Denver, staffed by veterinarians.
I point out that storks are never seen outside of the zoo, yet, human babies continue to arrive. Therefore, the stork theory of baby origins is obviously flawed.
I do not need to present another theory on baby origins, only that the vets (much as I like them) are wrong.
BTW, can anyone explain the appearance of human babies?
Reply: They seem, loosely, to have a positive correlation with the presence of diamonds. Diamonds may catalyze the formation of babies, or perhaps diamonds are the babies’ larval stage. ~ ctm
James Sexton says:
Mike, can you imagine what this world could have accomplished in the last 30 years if all of the mental, financial, and social energies hadn’t been diverted to this issue, from both sides of the debate?
I say this to my acquaintances but they look me back with poker face.
Congratulations to you all for keeping the debate and this site so vigorous.
Alexej Buergin says:
August 15, 2010 at 1:43 am
Sticky wicket: Some people call the cricket pitch “wicket”, and a sticky wicket would e.g. be a wet pitch which makes it a difficult situation for the batsman.
Another interpretation: The real wicket ist the construction of three stumps with two bails that the bowler is trying to hit. If the bails are sticking to the stumps (in climatology “because of some chewing gum” would come to my mind) it will be difficult for the bowler to make them fall.
Either that, or it’s named after Edward Greer Sticky, a 19th century batsman who was extremely difficult to bowl out. Sticky never scored many runs, because he worked on the precautionary principle that it was better to be safe behind his crease than sorry halfway down the pitch. In 1883, playing for Nottinghamshire versus Surrey, Sticky opened for Nottinghamshire and was not out for all of 3 runs scored after 17 hours at the crease, after having successfully blocked 337 deliveries.
tallbloke, to carry on the white flannelled fools analogy –
Dr WG Grace was bowled out on the first ball of a charity match, but continued to play, exclaiming “They came to see me bat, not to see you umpire”.
Somewhat like the team’s approach to scrutiny.
And BTW, the Ashes will be heading south this year, although unfortunately the MCC as usual will not have the good (W.G) Grace to actually send them, unlike the NY Yacht club in similiar circumstances. Work that out US readers.
Michael Jankowski says:
August 14, 2010 at 8:47 pm
I wonder how many emails went back-and-forth between team members today?
Not many I think, Gavins recent posting outside of RC saying temp paleo recontructions are not scientifically interesting show they may have already known about this paper for some time and were preparing the ground for ‘Well we never used this much for justifing AGW anyway’ and let the whole matter drop. They plan to fall back on the CO2 is a Greenhouse gas lab experiment as their last wheel on the wagon, pity no body has tried seeing if its true in an earth like atmosphere experiment.
Henry@Brian & Evan
Sorry Brian, I did try to follow those 2 discussions , but I am afraid it is above me or at least I don’t understand what they are talking about, mostly to do with thermology, I suspect..
I do believe that what I see is happening is simple enough: in the places where there is absorption in the molecule there is deflection of light (=radiation) . It absorps up to a point (probably causing some heat transfer in the process) until it is saturated. The only way I can understand what happens next is that I must see these (wavelengths ) spots in the molecule as places where the radiation is first absorbed and once filled it then becomes reflective, like a mirror. That is the only way to explain what I see is happening. Because of the random position of the molecule, 50% is send back in the direction where the light came from!
To give you a simple example. An observation I made here: if I stand in the African sun, and during the day the humidity goes up, then I can feel that the sun’s heat on my skin becomes less as the humidity increases.. . This happens because the water vapor is doing its re-radiation of sunshine and 50% of the sun’s radiations in the areas of where water absorps are sent back to space (remember: light cannot stand still).
What I discovered in my search for answers is that nobody made a detailed balance sheet of substances in the atmosphere as to how much they cool (by re-radiating sunshine) and how much they warm up (by re-radiating earthshine).
So my original question to Evan, who, as a lukewarmer, seemed sure that CO2 is a greenhouse gas, was : How do you know for sure that CO2 is a greenhouse gas, if nobody has some actual results from experimentations on the cooling and warming?
(remember that without oxygen/ozone/water vapor, CO2 and other gases in the atmosphere, an additional 25-30 % radiation would be slammed on top of our heads – this is difference in radiation between the top of the atmosphere and at sea level).
My recall is that Mann’s claim about the MWP was not the it had never occurred, but rather that It only had a regional effect that had been limited to Northern Europe. While I understand that substantial evidence has been found that indicates that the warming was global and not just regional, the examples cited as evidence that Mann got it wrong about the MWP in these comments have largely focused on Europe (such as grape growing in England). While I am very displeased with what seems to be Mann’s failure to even attempt to live up scientific standards, I still take an ACLU like perspective on this issue. Blaming him for a position that he did not take is not fair, and besides, there is so much more about many of his other claims that call for criticize.
Actually I don’t see the big importance of the article ! The reworked data representation still shows a hockey stick. Slightly different in shape than the original one. Also shows the reworked graph that we live in the highest temperatures since 1000 years. More alarming is the fact that the new representation shows temperature deviations of ± 1° C for the nowaday times. The original Mann graph kept the actual temperature rise restricted to ± 0,5°C. Personnally I would not see this paper as a victory of the skeptical climate science….but rather as a confirmation even a strengthening of the original Mann message….the earth is warming and it deas that rather fast !
Just wondering: Would it be legitimate to construct a couple of alternative graphs that fit within the data as circumscribed by M&W, i.e., within the error bars, that are equally plausible, statistically, with the hockey stick? You know, something for the shaft that is lumpy and bumpy, but still possible, given Mann et al.’s data? Leave the blade as is.
If legitimate, I would like to see them. So would the newspapers.
BTW, can anyone explain the appearance of human babies?
Reply: They seem, loosely, to have a positive correlation with the presence of diamonds. Diamonds may catalyze the formation of babies, or perhaps diamonds are the babies’ larval stage. ~ ctm
Not so, it’s BEER that causes babies. Fact
[REPLY – I theorize that it may relate to positive feedback from the beer/diamond combination. (I am looking for volunteers for a robust series of field-tests.) ~ Evan]
C Colenaty:
At August 16, 2010 at 4:10 am you assert:
“My recall is that Mann’s claim about the MWP was not the it had never occurred, but rather that It only had a regional effect that had been limited to Northern Europe. While I understand that substantial evidence has been found that indicates that the warming was global and not just regional, the examples cited as evidence ”
Sorry, but that is an Orwellian rewriting of history.
The MBH ‘hockey stick’ was constructed (contrived?) from proxy data obtained from the Northern Hemisphere mostly in Northern Europe. It showed no MWP.
So, if it were to be claimed that the MWP was “regional” on the basis of the analyses by MBH then those analyses showed the Northern Hemisphere was the region where the MWP did NOT happen.
Richard
Willem de Rode:
Please read the original paper (it is linked from the above article).
Altenatively, if that is too difficult for you, then read the several contributions (above) that have explained the matter and refuted your point. To save you finding them, I copy one randomly selected example here:
“Mike Jowsey says:
August 14, 2010 at 8:32 pm
duckster says:
August 14, 2010 at 7:48 pm
Looking at the paper above…
The main point of this paper is to debunk the maths Mann used. You can get similar hockey sticks by using random numbers. Speak to that subject please.
By shifting focus to whether or not the graph shows a MWP is a strawman and is completely irrelevant to the point of the paper. Besides, the graph (fig.16) uses the same proxy data Mann used, with correct maths. Mann’s proxy data (and maths) explicitly set out to remove the MWP so it is no surprise that his biased proxy selections camouflage the MWP. Nevertheless, fig.16 does show temperatures 1000 years ago were on a par with today’s (according to Mann’s proxies).”
On a WUWT thread it pays to read the existing comments before posting one yourself.
Richard
Willem!
Dont you see the elephant? The statistic METHODS climate science use is flawed.
With flawed methods not understanding the underlying data you end up with wrong conclusions.
“Environmentalism, which in its raw, early form had no time for the encrusted, seized-up politics of left and right, has been sucked into the yawning, bottomless chasm of the ‘progressive’ left.”
…-
“Confessions of a recovering environmentalist
Paul Kingsnorth, 16 August 2010″
“Environmentalism, which in its raw, early form had no time for the encrusted, seized-up politics of left and right, has been sucked into the yawning, bottomless chasm of the ‘progressive’ left.” A personal, twenty-year journey through the world’s wild places and the movements to protect them is also, for Paul Kingsnorth, an education in the limits of a project that has forgotten nature and lost its soul.”
“Some see Nature all ridicule and deformity … and some scarce see Nature at all. But to the eyes of the man of imagination, Nature is imagination itself – William Blake
Scenes from a younger life # 1:
I am 12 years old. I am alone, I am scared, I am cold and I am crying my eyes out. I can’t see more than six feet in either direction. I am on some godforsaken moor high up on the dark, ancient, poisonous spine of England. The black bog-juice I have been trudging through for hours has long since crept over the tops of my boots and down into my socks. My rucksack is too heavy, I am unloved and lost and I will never find my way home. It is raining and the cloud is punishing me; clinging to me, laughing at me. Twenty-five years later, I still have a felt memory of that experience and its emotions: a real despair and a terrible loneliness.”
http://www.opendemocracy.net/paul-kingsnorth/confessions-of-recovering-environmentalist
http://pajamasmedia.com/richardfernandez/2010/08/15/talking-down-to-a-bigoted-nation/#comment-119296
http://www.smalldeadanimals.com/archives/014654.html
Willem de Rode,
This paper is extremely important. Here’s why:
The MBH98 hockey stick provided two separate arguments for the CAGW crowd. First, it showed a recent, rapid rise in temperature [the blade], and second, it showed that no MWP occurred [the stick]. That would make the current rise in temperature unprecedented.
Both claims were based on faulty statistics used improperly, and on very carefully picked proxies, selected after many computer runs and using statistically invalid methods, until one was found that gave the desired hockey stick shape. Mann threw out the proxies after 1960 because they stopped showing a rise in temperature, and he replaced them [without the necessary acknowledgement] with an instrumental overlay after 1960.
When the statistical analysis is done correctly using Mann’s own carefully selected tree ring proxies, the resulting graph shows that the current warming has happened just like the past MWP warming that happened well before the industrial revolution. That destroys the MBH98 hypothesis that current temperatures are “unprecedented.”
Since what is occurring now has happened in the past [and the planet has warmed even more, prior to the MWP], the null hypothesis remains standing: no one has falsified the theory that the observed temperatures changes are the result of natural variability, which fully explains the current temperature fluctuations without the need for an extraneous variable like CO2. Occam’s Razor warns against adding any unnecessary variables to an explanation that completely describes a hypothesis.
Next, this proper statistical analysis means that MBH98, MBH99, and follow-up Mann et al. papers are far from robust, and in fact are so riddled with bad statistics that they are essentially worthless; they are falsified.
Finally, Mann claims that no MWP happened. This paper clearly shows the high temperatures in the Middle Ages — verifying supporting historical documents and first-hand contemporary accounts from around the world showing the MWP was at least as warm as today, and very likely warmer.
This paper decisively breaks the hockey stick by showing a clearly recognizable MWP, and by showing that current temperatures are within past parameters. Nothing unusual or unnatural is occurring, and the coincidental rise of CO2 has much less to do with the [very mild] 0.7° temperature rise over the past century and a half than the effect of natural variability.
You conclude by saying “the earth is warming and it does that rather fast!” But even a chastened Phil Jones shows that the current rise has happened repeatedly.
None of this would be necessary if Michael Mann had produced his data and methodologies as required by the scientific method, and as required by the written policies of the journals that published his findings. Mann understands very well that producing his methods — paid for by public taxes — would cause his iconic chart to be promptly falsified. So for the past twelve years he has used every trick in the book to avoid allowing other scientists the opportunity to replicate his methods.
Now Mann’s statistics have been debunked, destroying his hockey stick. Whether or not you believe that is unimportant doesn’t matter. This paper is yet another torpedo in the side of the Mann CAGW ship. It’s going down.
Willem de Rode says:
August 16, 2010 at 4:24 am
Actually I don’t see the big importance of the article ! The reworked data representation still shows a hockey stick.
————Reply:
Mann’s central point is that the current warming is UNPRECDENTED–he does that by using bogus statistical methods to flatten past temperature variations. You yourself state that it shows temperatures this warm 1000 years years ago, a direct refutation of Mann’s central point (whether it was regional or global is immaterial, although more evidence indicates it was a global phenomena, not just regional).
You see, the “C” in CAGW stands for “Catastrophic”; hence, if temperatures in the past have been as warm or warmer than they currently are, it means two things: It wasn’t due to man’s influence and it won’t have catastrophic impact. Of course, the “climate scientists” that push their CAGW agenda like Mann through the use of home-made “statistics” are going to ignore this, but the rest of the world (particularly thinking voters and most likely a certain attorney general from Virginia) are going to see through the charade. By the way, the rate at which the earth is currently warming is a very debatable topic, since so many temperature stations have been dropped, and due to other irregularities (for example, their “homogenization” adjustments are highly questionable as pointed out in a companion post on this site that indicates New Zealand’s NIWA is being sued for “cooking” the temperature data); there is far more information of this type that you can find in past postings here at WUWT. Not only are “climate scientist’s” mathematical abilities highly questionable (and perhaps erroneous on purpose), but their data-gathering abilities are highly suspect too.
Willem de Rode says:
August 16, 2010 at 4:24 am
“Actually I don’t see the big importance of the article ! The reworked data representation still shows a hockey stick.”
William, I don’t mean to be overly critical, but you have, as many others here, simply looked at the graph and drew an errant conclusion. In doing so, you’ve made it abundantly clear that you haven’t even bothered to read the discussion, (I know it is lengthy, but you could at least skim) much less the paper itself. The authors didn’t seek to make a statement of past or present temperatures or anomalies. They were trying to determine if the temp proxies(ie, tree rings) were valid proxies. The graph was presented to show levels of uncertainty not some perception of reality.
From the paper. “We decompose the uncertainty of our model’s backcast by plotting the curves drawn using each of the methods outlined in the previous three
paragraphs in Figure 16. As can be seen, in the modern instrumental period
the residual variance (in cyan) dominates the uncertainty in the backcast.
However, the variance due to β uncertainty (in green) propagates through
time and becomes the dominant portion of the overall error for earlier periods.
The primary conclusion is that failure to account for parameter uncertainty
results in overly confident model predictions.”(emphasis mine)
As you can see, they don’t have any confidence this graph(or any other from the proxy data) reflects reality. Do yourself a favor and read the paper. The statistics are difficult(for me anyway), the read and reasoning are not.
Ken Harvey says:
August 15, 2010 at 5:44 am
…Why would they want to spend some of their grant money on professional numbers men? …
Note well that your drugs and food additives are approved with even greater prudent savings on unnecessary expenditure on professional statisticians.
___________________________________________________________
Food and drug safety is the other worldwide hoax. That is why all the real data on the cause of food borne illness is swept under the rug. There is very big money in controlling the food supply. And just as tax and regulation (Markey’s Cap & Trade bill) is the means of controlling energy, Markey’s other bill “Food Safety” is all about gaining complete control the food supply
“Food is power! We use it to change behavior. Some may call that bribery. We do not apologize.” These are the words of Catherine Bertini, Executive Director of the United Nations World Food Program, former U.S. Assistant Secretary of Agriculture – UN World Food Summit in November of 1996.
REFERENCES:
To understand the implications of food safety regulations on private kitchen gardens you have to understand The Interstate Commerce Clause and The Kitchen Sink
The WTO and the Politics of GMO
History, HACCP and the Food Safety Con Job
The Festering Fraud behind Food Safety Reform
FARM ANIMALS AND CORPORATE PATENT STRATEGIES
STOP ‘MONSANTOSIZING’ FOOD, SEEDS AND ANIMALS!
No End Seen to Cartel’s Destruction of Food Capacity
Food Safety Bill:
HR 2749: Totalitarian Control of the Food Supply
Text of H.R. 2749: Food Safety Enhancement Act of 2009
(2009) HR 2749 Food Safety Regulation Amendments: A Politicians summary
http://aboutpolitics.com/politicians/Colorado-CO/Markey/Executive%20Branch
(How interesting–I see Smokey and I often argue the same points in tandem! (And no, we’re not corroborating behind the scenes!) Of course, I think Smokey has a deeper grasp of the subject matter than I do, so make sure you concentrate on his replies.)
[Reply: GMTA. ~dbs, mod.]
There’s another point in the article that is poignant. They talk about how one will select series that agree with known temperatures. This is something you should never do in statistics. This ends up skewing the data toward what you want it for the data that you know, but will lead to erroneous data everywhere else.
In classical cryptography, you can see the same thing with Vigenere type ciphers. Suppose you think it’s English, you can test for that by calculating the IC. Each language has a different IC. But if you get a huge spike in IC, it will look strange, but it is meaningless. You cannot take this high IC, even though it is very rare to get such a value, to mean you’ve found anything significant. That high IC was found after the fact.
Same thing with tree ring proxies. You cannot select good matches AFTER THE FACT. You need to have a hypothesis BEFOREHAND and then test for that will ALL data. If it happens that there are serious flaws outside of this (like something went wrong with the collection of tree ring data), then sure you can remove it. But otherwise, all data must be use within the hypothesis. This is why the paper included all the data. If one of them skews the data, then that can be analyzed later. However, the first step is to include everything. If the paper in question did not do this, they could be accused of cherry picking themselves and of doing what they themselves say cannot be done. Which is to select tree series based on what we already know.
In short, the correct way is to make a hypothesis and then check to see if it fits the data we already have. Not the other way around.
I find that this is the more important point of the paper that has perhaps been glossed over.
It’s the same problem that happened with hiding the decline. If a proxy series does not match the instrumental data, then it’s possible that it won’t match actual data in the past either. So that entire series is no good. By the same token, if some tree proxy series don’t match actual temperatures (or changes in temperature), then none of the tree series can be trusted, even those that do match, because we don’t know if it’s just by chance that they match the last 100 years or so.
[REPLY – Gosh, yes. When I was reviewing CRN ratings for surface stations I avoided looking at the raw trends first. ~ Evan]
Barefoot boy from Brooklyn says:
August 16, 2010 at 4:37 am
“Just wondering: Would it be legitimate to construct a couple of alternative graphs that fit within the data as circumscribed by M&W, i.e., within the error bars, that are equally plausible, statistically, with the hockey stick? You know, something for the shaft that is lumpy and bumpy, but still possible, given Mann et al.’s data? Leave the blade as is.
If legitimate, I would like to see them. So would the newspapers.”
One could, but it wouldn’t be legitimate. The paper concludes the proxy data itself isn’t sensitive enough to pick up the upticks (nor downturns) in our historical data. Given the margins of error in the various graphs and analysis, a child with a crayon would be as valid as anything you’ve seen if the graph was constructed by the proxy data used in paleo-climatology.
From the paper, “Still, it seems there is simply not enough signal in the proxies to
detect either the high levels of or the sharp run-up in temperature seen in
the 1990s. 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.” and “Since our model cannot detect the recent
temperature change, detection of dramatic changes hundreds of years
ago seems out of the question.”
Barefoot, it is tempting to do such things. And I suspect it has been done to the populace by less scrupulous people. But there wouldn’t be justification for it. Again, the graphs are only representative of the proxy data, which, the authors state doesn’t have the ability to detect historical temps to such a sensitive degree. The reality is the temps could be and may be greater and lower than the error bands of the graphs. See figure 15 for as to why I stated such.