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”)
JP Miller says:
August 19, 2010 at 7:28 pm
“Sorry if the following comment has been made in this 800+ comment thread, but as significant as McS-W’s criticism of MBH98 might be, I think it diverts attention from the real problem(s): the poor proxies and wholly unjustified way they are constructed.”
Yeh, sorry if some of the discussion has varied there, but MBH98 wasn’t the topic of the study.
From the paper, “we work entirely with the data from Mann et al. (2008)”
The entire point of the paper is exactly for the reasons you stated(they said as much), and their conclusions bare that point.
Richard,
thanks for being specific.
You musn’t be reading my posts too well. I’ve already stated that PCA analysis was one of the principals criticisms against MBH.
And this is the analysis that you believe is common to all the studies in the paper I cited.
Actually, the term ‘hockey team’ is not self-adopted, but was initiated by critics of paleoclimatologists – Stephen McIntyre was the first, I believe.
So now we can cross reference the papers to see whether Mannian PCA analysis was adopted by all of them.
Going from the list you cited:
Jones et al 1998 was published months earlier than M98.
Huang et al 2001 is a study of 616 bore holes. There is no principal component analysis, and their methodology is based on their previous (1996) work, and that of thermally induced temperature reconstructions from studies earlier in the 20th century. No PCA
Briffa et al (2001) use an age banding method (differently from M98) and explain their PC analysis in great detail. It is distinct from MBH 1998 in all respects.
Esper et al (2002) employ Regional Curve Standardization (no PCA). They use this technique as an independent test of MBH 1999. They do not reference M98.
Moberg (2006) calibrates from variance and not PCA. Their methodology is quite distinct from M98.
Osborn and Briffa (2006) methodology avoids calibrating against 20th century temperatures, and instead attempts to resolve the proxy records themselves. No Mannian PCA.
These are not the only distinguishing features of the various reconstructions. Amongst most of them, but not all, there is some overlap of proxies, but they are treated differently. The PCA of MBH 98/99 are particular to those studies, and do not form the basis or bias of other millennial reconstructions.
The paper I cited which assesses the relative merits of these approaches, itself discards Mannian PCA, the controversial US tree ring proxies, and the contentious Yamal series, and still corroborates the general story told by independent papers.
You have asked me to refocus on the paper to hand. While agreeing that it contends there is far more uncertainty in the early millennial record, I point out that their own estimates tend to comport with the IPCC result that late 2oth century temps are anomalously warm. They also maintain that the rate of warming during the 20th century appears to unprecedented in the last 1000 years.
This is not an attempt to resurrect MBH 98/99. Rather, I think it is important to separate broad misconceptions from more nuanced results. We cannot discuss the issue properly if we labour under false impressions.
It’s worth noting that M&M’s later papers reconstructed temperatures from 1400, and their corrections resulted in 15th century temps that were slightly lower than those of the late 20th century. They found lower 15th century temps (lower by 0.2K) after correcting problems with their 2003 study.
If we completely discard Mann’s work, there are other, independent methodologies, that agree with the IPCC findings. The 2001 IPCC report, for example, examined a number of reconstructions, and made conclusions that were less assertive than MBH 1999 as a result of combining the understanding. IPCC 2007 drew on later work and reached similar conclusions.
Tsk, sorry for the formatting error.
Jan Zeman says:
August 19, 2010 at 6:10 pm
“I would think that the proxies like treerings always would be result of multiple factors………”
Yes they are. Obviously, tree rings measure the growth of the specific trees. From the growth rate(rings), we can ascertain atmospheric CO2 and humidity and soil nutrient content and rainfall. From that “knowledge”, it is an easy jump to “know”the temperatures on a yearly, (decadal?) basis. No way that can’t be truth!
Well, only “scientists” know how to do that, it is way beyond “common” people to be able to follow such insight and knowledge.
Re: JP Miller says:
August 19, 2010 at 7:28 pm
“… Thorough evaluation of the base data is likely to be a more powerful way of showing MBH98 to be sheer nonsense than showing their stats are bad.”
Yes but this is sort of like jailing Al Capone for tax evasion 😉
Cheers
Michael
Chris,
Bob Brown’s pronouncement is not supported. That the rate of warming in the 20th century seems to be unprecedented in the last 1000 years is, as is the estimate that late 20th century temps seem to be warmer than any in the last 1000 years, including by the paper introduced at the top of this thread criticising MBH. When Mann is dead, there is still Huang, Jukes, Rahmstorf, Moberg, Briffa, Crowley, Jones, Esper, Oerlemans, Hegel and others to deal with.
But even if you outright “killed the hockey stick,” that would have little to no impact on the rest of AGW – global warming theory, radiation budget, stratospheric cooling, observed sea level rise, increasing CO2, species migration, early flowering, instrumental record, diminishing Arctic sea ice, projections – none of these are impacted by the hockey stick controversy. There are 29 000 independent observations (one of them is the instrumental temperature record) that tell uis the globe is warming, and basic physics tells us that CO2 will cause temps to rise. Millennial reconstructions, as noted by McShane and Wyner in the paper that kicked this thread off, don’t really make much of an impact here.
Still waiting for a response at DeepClimate. Did they have to regroup and get yet another set of talking points?
barry says:
August 19, 2010 at 9:04 pm
A lot!
Barry, you’re almost there!!!
Kinda reminds me of the (we thought) debunked “cold mother syndrome” once considered to be the cause of autism. It didn’t die, it just migrated as a cause to other childhood difficulties.
barry says:
August 19, 2010 at 9:04 pm
barry, one of the tenets of CAGW is that what we are seeing is unprecedented. Be it warming or melt or sea levels, or what ever. It is always unprecedented. Not to you or me, but to the populace. Many of the expressed concerns of the alarmist crowd isn’t really a concern but a welcomed event. But you know that. Moreover, most, if not all of the alarmism is over events that have happened many times already.
I know, and I know you know, there are many things occurring on this earth that are alarming, that have the potential to be catastrophic, that need our attention, but a bit of warming……….???!!??!!??! Tell me again why we need to address the imagined difficulties of the future while we can’t solve the real difficulties of the world today?
This has got to be the ultimate “do like I say……”
I submit we are sacrificing our humanity today to save ourselves from an imaginary harm tomorrow.
Humanity has always thrived better in warmer climates. The ice melt has happened in our father’s lifetimes. You know ice melt won’t cause sea rise flooding. Why? Because it didn’t happen already. Plants blooming early? Oh, the horror!!!! Budgets? Well that’s the crux of the contention, isn’t it? I know we can’t create matter. I know the water budget is fixed.(for the most part). Given H2O is the most well known and the overwhelming major element of the earth, we know that H2O will act in the correcting manner it always has.
I find it incredible that people are still prepared to defend the hockey stick, icon or not, in its various permutations. Briffa is a cheery-picker and obscurantist full stop. Mann is something else again. His first farrago used PCA, and his second CPS and EIV; the techniques are academic because obfuscation is the order of the day; in his second paper [08] Mann discarded proxies if they were inconsistent with hemispheric or GMST – the regional effect and information was discarded! -; LTP was not even considered and by emphasising the instrument record as a calibration [ie the data was calibrated down to the proxies, whereas M&W calibrated up from the regional proxies] he preferred an infilled instrument record using RegEm on non-stationary [because the infilled instrument record could be anywhere in the world and time] data to the gauntlet run proxies. Basically, Mann 2 compared proxies of proxies with an ‘instrument’ temp record which was infilled according to which location and time best matched the proxies!
As for Mann1 Jolliffe said it all: “given that the data appear to be non-stationary, it’s arguable whether you should be using any type of PCA.” You shouldn’t be using PCA with either dendroclimatic or temperature data because both are non-stationary; temperature inherently so because it has a unit root element and dendros because they are regionally different, something which Mann ignores.
The hockey stick, icon or not, is junk.
That, of course should be Briffa is a “Cherry picker”; he may be ‘cheery’ as well; I don’t know or care.
Barry, August 19, 2010 at 9:08 am, you say of the HS that
“The graph does not appear in An Inconvenient Truth.”
This is completely wrong. Al Gore claimed it was Thompson’s, but he was wrong, as Tim Lambert points out at
http://climateaudit.org/2007/11/09/al-gore-and-dr-thompsons-thermometer/
And Thompson refuses to correct the public record:
http://climateaudit.org/2008/01/13/sticking-thermometers-in-places-they-dont-belong/
Anyone see this it totally redefines “Moranic”
http://blogs.discovermagazine.com/80beats/2010/03/29/could-turning-the-oceans-into-a-giant-bubble-bath-cool-the-planet/
How can anyone possibly propose something so totally impractical as this and then expect to be ever taken seriously?
Those who can do. Those who can’t teach.
Russell teaches?!
Barry says:
basic physics tells us that CO2 will cause temps to rise
Henry says
Barry, I could not find that evidence. All I can find is stories and assumptions. We had an argument about that here. Dave Springer gave up. I assume his silence means that he agrees that he can not prove to me conclusively that CO2 is a green house gas
e.g. look here
http://letterdash.com/HenryP/more-carbon-dioxide-is-ok-ok
In case you missed, here are my questions
Dear Prof. Shillington (Barry!)
I heard you on the radio this afternoon and it seemed to me that you are also getting to a point where you are starting to get doubts about the influence of CO2 on global warming. Please bear with me to hear my story, and see if you can perhaps provide an answer to the questions that I have.
A few months before Climategate broke, I started my own investigations to see if my carbon footprint (CO2) really causes global warming, as claimed. To start off with, I found Svante Arrhenius’ formula completely wrong and since then I could not find any correctly conducted experiments (tests & measurements) that would somehow prove to me that the warming properties of CO2 (by trapping earth’s radiation between the wavelengths 14-15 um) are greater than its cooling properties (by deflecting sunlight at various wavelengths between 0 – 5 um). Even more disconcerting to me was finding that pupils at school and college are shown experiments with 100% carbon dioxide (representing earth’s atmosphere of only 0.04% or 380 ppms CO2!) and a light bulb as an energy source (representing the sun!). Obviously such crude experimentation can only lead to incorrect results and completely incorrect conclusions…e.g. what about the IR and near IR absorptions of CO2 and the UV absorptions of CO2 that have only been discovered recently and that also deflect sunlight?
I also found untruths in Al Gore’s story (An Inconvenient Truth). A lot of CO2 is dissolved in cold water and comes out when the oceans get warmer. Any chemistry student knows that the first smoke from the (warmed) water in a kettle is the CO2 being released. So, quite a number of scientists have reported that the increases of CO2 in the atmosphere in the past lagged the warming periods by quite a few hundred years… Cause and effect, get it? Smoking causes cancer but cancer does not cause smoking. But Al made it look from the past that our CO2 output must be the cause of global warming.
Just to put the carbon dioxide content of the atmosphere into the right perspective: it has increased by about 0.01% in the past 50 years from ca. 0.03% to 0.04%. This compares with an average of about 1 % for water vapor in the air. Note that most scientists agree that water vapor is a very strong green house gas, and a much stronger green house gas than carbon dioxide… (if indeed carbon dioxide is a green house gas, which, like I said before, has yet to be proven to me). It is also logical for me to suspect that as a result of human activities relating to burning, bathing, cooking, boiling, countless cooling processes (including that for nuclear energy), erection of dams and shallow pools, etc. a lot more water vapor than carbon dioxide is put up in the air.
The paper that confirmed to me that CO2 is (also) cooling the atmosphere by re-radiating sunshine is this one:
http://www.iop.org/EJ/article/0004-637X/644/1/551/64090.web.pdf?request-id=76e1a830-4451-4c80-aa58-4728c1d646ec
they measured this radiation as it bounced back to earth from the moon. So the direction of the radiation was:sun-earth-moon-earth. Follow the green line in fig. 6, bottom. Note that it already starts at 1.2 um, then one peak at 1.4 um, then various peaks at 1.6 um and 3 big peaks at 2 um.
This paper here shows that there is absorption of CO2 at between 0.21 and 0.19 um (close to 202 nm):
http://www.nat.vu.nl/en/sec/atom/Publications/pdf/DUV-CO2.pdf
There are other papers that I can look for again that will show that there are also absorptions of CO2 at between 0.18 and 0.135 um and between 0.125 and 0.12 um.
We already know from the normal IR spectra that CO2 has big absorption between 4 and 5 um.
So, to sum it up, we know that CO2 has absorption in the 14-15 um range causing some warming (by re-radiating earthshine) but as shown and proved above it also has a number of absorptions in the 0-5 um range causing cooling (by re-radiating sunshine). This cooling happens at all levels where the sunshine hits on the carbon dioxide same as the earthshine. The way from the bottom to the top is the same as from top to the bottom. So, my question is: how much cooling and how much warming is caused by the CO2? How was the experiment done to determine this and where are the test results? (I am afraid that simple heat retention testing might not work here, we have to use real sunshine and real earthshine to determine the effect in W/m3 [0.03%- 0.06%]CO2/m2/24hours). I am also doubtful of just doing analysis (determining surface areas) of the spectral data, as some of the UV absorptions of CO2 have only been discovered recently and I also think the actual heat caused by the sun’s IR at 4-5 may be underestimated, e.g. the amount of radiation of the sun between 4 and 5 maybe small but how many Watts does it cause? Here in Africa you can not stand in the sun for longer that 10 minutes, just because of the heat of the sun on your skin.
Anyway, with so much at stake, surely, someone actually has to come up with some empirical testing?
If this research has not been done, why don’t we just sue the oil companies to do this?? It is their product afterall.
I am going to state it here quite categorically again that if no one has got these results, then how do we know for sure that CO2 is a greenhouse gas? Maybe the cooling properties are equal to the warming properties?
I have also been thinking of the ozone concentration in the air: Assuming that its cooling properties are higher than its warming properties (did anyone test that?), then lower concentrations, as in the past, before CFC’s were banned, can be a cause for global warming; increasing levels, as noted in the past 10 years can be a cause of global cooling?
So the net effect of the increases in CO2 and ozone is close to zero or even cooling?
(I have no financial interest in any of this, I just started my investigations because I felt a bit guilty about driving my car)
James,
Depends what you’re talking about and in what context. In the world of soundbytes, there is much to complain about on both sides of the debate.
Best estimates give that:
The current rate of warming is unprecedented.
The current rate of CO2 rise is unprecedented.
The current atmospheric concentration of CO2 is unprecedented in the Quaternary period (where land formations and solar output has remained constant)*.
Arctic sea ice coverage averaged over the past decade is the lowest in the last century. There are no historical records of an ice free Arctic.
Temperatures have been higher in the past (certainly in the geological record). CO2 levels have been much higher in the past. The current rate of change doesn’t appear of have precedent, and where the climate has changed rapidly and profoundly, it is accompanied by great stress on the biosphere and species die-off (not that I am suggesting AGW poses a mortal threat to the continuation of our species).
If you want to complain that the popular press and politicians have exaggerated or been inaccurate on the issue, I will completely agree with you – but that applies to both sides of this debate. On the actual science, slogans and soundbytes are irrelevant. The science must be understood first, then we can accurately assess the validity of various rhetoric. In terms of my personal understanding and decision-making, I see the issue as one of risk management, nothing more.
* (Previous epochs are very different to the current configuration of the biosphere, making one-for-one comparisons useless. For example, where CO2 levels have been higher in the pasty but not temperatures, tectonic configuration is vastly different, bringing increased albedo to offset greenhouse warming, or solar output has been significantly less – the sun has become hotter over millions of years, and will continue to do so in the long-distant future)
A counter argument is out for this paper :-
http://deepclimate.org/2010/08/19/mcshane-and-wyner-2010/
I see the old its not peer reviewed is trotted out again, shameless really.
Henry Pool,
good questions for which I don’t have deeply considered answers. I have read here and there that radiation budgets for the greenhouse effect do include backscatter and reflection from atmospheric gases (eg, Ramanathan 1978), and that reflection is considered to be a very negligible factor.
Also, it doesn’t take much to consider that, even if reflection were a non-negligible influence, only half the planet is affected at any one time, while greenhouse properties are in effect all over the sphere. A key indicator to consider here is that warming has been greater for nighttime than daytime temps over the last century.
It would be interesting to pursue this, but we should do that in a more appropriate thread.
latitude says:
August 19, 2010 at 7:42 am
RR Kampen says:
August 19, 2010 at 6:18 am
There are no apparent other mechanisms
====================================
Of course there is RR.
The most obvious is the climate changes.
So the mechanism explaining recent climate change is: climate change?
Do you think there is magic involved in climate change? You know – changes without causes?
It’s been warmer in the past, CO2 has been higher, extremely high levels of CO2 did not insulate the planet or prevent an ice age, the oceans hold and release CO2 according to temps, and on and on………
There are more causes of climate change. Momentarily the increase of a strong greenhouse gas is just the most important one.
A long time ago, CO2 was much higher. It went down into coal and oil, so went global temperature. Now were digging up historical hot epochs…
The whole AGW theory could not be any shakier or weaker if you look at it.
What I see is that you are projecting your ignorance of the subject on the professionals studying it.
Richard S Courtney says:
August 19, 2010 at 7:46 am
Thank you for your elaborate response. I will pick out two lines:
The hypothesis predicts most warming of the air relative to the surface at altitude in the tropics.
In reality the hypothesis predicts most warming at high latitudes, particularly northern high latitudes. The hypothesis does so now and it did so when I studied climatology in an era the IPCC still had to be set up. The observations are conform hypothesis.
That’s 40 years of cooling and 28 years of warming. Global temperature is now similar to that of 1990.
Reality: the past decade was warmest; decade 1990’s second warmest, decade 1980’s third warmest and the difference between the nineties and tens is bigger than between the eighties and nineties. In other words: warming is accelerating.
Also, we are almost on par with 1998, not 1990 – without a superNiño and during deep solar minimum: http://www.weerwoord.be/uploads/14820101561.png . Some ice is melting, too.
AGW cannot be debunked because it is the reality.
By denying it, you are giving Al Gore and the carbon tax terrorists total right of way.
And you don’t seem to see it. Yet.
There are some advantages to warming. Emphasize THEM.
Barry:
At August 19, 2010 at 8:43 pm you assert:
“If we completely discard Mann’s work, there are other, independent methodologies, that agree with the IPCC findings. The 2001 IPCC report, for example, examined a number of reconstructions, and made conclusions that were less assertive than MBH 1999 as a result of combining the understanding. IPCC 2007 drew on later work and reached similar conclusions.”
OK. Let us not take my word for it but see what the ‘hockey team’ have to say about it in their own words in the leaked emails which you can read at
http://www.eastangliaemails.com/index.php
Mann:
“..The key thing is making sure the series are vertically aligned in a reasonable way. I had been using the entire 20th century, but in the case of Keith’s, we need to align the first half of the 20th century w/ the corresponding mean values of the other series, due to the late 20th century decline.”
“Keith” is Briffa . And Briffa wrote:
“.. For the record, I do believe that the proxy data do show unusually warm conditions in recent decades. I am not sure that this unusual warming is so clear in the summer responsive data. I believe that the recent warmth was probably matched about 1000 years ago. I do not believe that global mean annual temperatures have simply cooled progressively over thousands of years as Mike appears to..”
But Briffa also used the skewing of the calibration that Mann adopted but for a diffrent choice of calibratio period (as Mann suggested; see above in this post).
THE SKEWING – NOT THE USE OF PCA – IS THE FLAWED METHODOLOGY INTRODUCED BY THE ‘TEAM’.
All the analyses that used this erroneous distortion of PCA, including Briffa’s, are disproved by the McS&M.
Richard
“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 ”
Has it been removed? Maybe I’m blind but I can’t find it. Can someone provide a fully resolved link?
James Sexton says:
August 19, 2010 at 8:48 pm
Jan Zeman says:
August 19, 2010 at 6:10 pm
““I would think that the proxies like treerings always would be result of multiple factors………”
Yes they are. Obviously, tree rings measure the growth of the specific trees. From the growth rate(rings), we can ascertain atmospheric CO2 and humidity and soil nutrient content and rainfall. From that “knowledge”, it is an easy jump to “know”the temperatures on a yearly, (decadal?) basis. No way that can’t be truth!”
Not to mention the genetic makeup of individual trees which can affect growth… but we won’t mention that ;o)
No one has noticed but this must have been Google’s smartest ever way of avoiding this getting out there. Type “hockey stick climate”and you will get one link dealing with this. They have gotten around it by making the authors names + paper title prominent but of course the general population would never use this to find info about hockey stick…..
The silence from RC is deafening.. not one post, or as I see, any comment, allowed. This of course is a godsend as it confirms their worst fears….