So Wegman's comment “Method Wrong + Answer Correct = Bad Science” is meaningless since the method part of the project was correct and the statistical point was more of a “you didn’t do it my way” response.
Wegman said that the answer was correct?
I guess that Mann et al just had a stroke of good luck.

I have never been able to figure out why Mann would not release his data for years after he published his paper so that his work could be independently verfied by others. Independent verification does not mean that you give the data only to your friends for analysis. Mann's work was publicly funded, therefore the data belongs to the taxpayers.

Re: 'going back 1000 years, that Mann's conclusions were at best "plausible".'

Is that their wording, Paul, or did you cite it improperly?

From what I read of the NAS report, their conclusions were that the global mean temperature is warmer than at any point in the last 400 years and that it is plausible that global mean temperatures are warmer than at any point over the last 1000 years.

These two phrasings are quite different in their meaning.

Arie,

Climate changes are not unusual. Static temperatures would be unusual.

When temperatures dropped to a multi-thousand year minimum as they did in the mid 19th century, it is perfectly reasonable for them to increase.

This is not an answer to your question, but rather a statement of what has been happening to the climate for as far back as scientists can determine. Temperatures fluctuate. The cause of the recent warming is most likely a combination of forcings, rather than one particular change. The CO2 increase over this time of 0.0001 fraction of the air, is a contributing factor. There are other factors as well such as solar flux, and albedo changes.

Arie,

The issue of what is "normal" is at the heart of the climate debate. Frankly, I do not know what "normal" climate is nor even how it could be scientifically determined with the information which we have available today. It may not even be meaningful to define "normal" climate, but it does make good sense to determine upper and lower confidence levels.

The whole issue of normalcy does enter the climate debate specifically at sites like RealClimate (RC). There is an underlying assumption on the part of at least some of the people who run RC that we have had a stable climate (that is relative normalcy) until recently when the globe experienced unprecedented warming. Remember that RC was started by Michael Evan Mann and friends to support Mann, Bradley, and Hughes's papers which featured the famous hockey stick graph. MBH98 and MBH99 featured proxy reconstructions which not only showed recent warming but also showed greatly reduced variation during the period from 1000 to 1850 AD. The graph indicated that the world's climate had been relatively stable until the middle of the 19th century, when temperatures moved sharply higher.

Mann's most recent paper (available on his Penn State web site - without co-authors) proposes, among other things, that both the MWP and the LIA were European, rather than global phenomena. This is consistent with the Michael Mann and Gavin Schmidt post on RC which you referenced. If Mann's most recent paper is correct, then it supports the conclusions of MBH98 and MBH99 that until recently the globe's climate was relatively stable until the mid 19th century.

In spite of the fact that Mann uses some coral proxies to support his position, there are many other proxies which indicate that both the MWP and the LIA were, in fact, global rather than European.

Stephen, here is what the NAS said: === "the committee finds it plausible that the Northern Hemisphere was warmer during the last few decades of the 20th century than during any comparable period over the preceding millennium." ===

They also said: === "Even less confidence can be placed in the original conclusions by Mann et al. (1999) that “the 1990s are likely the warmest decade, and 1998 the warmest year, in at least a millennium." ===

http://fermat.nap.edu/books/0309102251/html/4.html

... can be placed in the posts of people who misrepresent the science.

There is considerable difference between something being "plausible" (which the Oxford defines as "seeming reasonable or probable") and your rather more colourfuil characterization of 'at best "plausible".' It's pretty clear what point Wegman was trying to make. And it seems equally clear that you're not that eager to accept it.

"Even less confidence" is a direct quote from the National Academy of Science report Richard. It is that quote and the "plausible" one that, taken together, imply less statistical validity in Mann's results pre-1600.

I am confused by what point you believe Wegman made. He was quite critical of Mann's temperature reconstruction. You seem to imply that you are in agreement with this criticism.

Regards,

Who cares what point he made? The whole Mann conversation is intended only to distract and undermine confidence in any conclusion that anthropogenic climate change is real.

You, too, seem determined NOT to talk about the other nine reconstructions represented on the attached graph - none of which has been challenged on any basis and all of which reach the same conclusion.

As ever, the DeSmogBlog has very little expertise in science, but we sure can recognize spin when we see it.

Richard, if you don't want to talk about Wegman, why post an article about him?

Mann's temperature reconstruction is "controversial", as you state, because claims, not supported by the evidence, were made from it.

As for the other nine reconstructions, interestingly, they don't show the Little Ice Age of Midieval Warming Period either!

The whole Mann "conversation", as you call it, is part and parcel of all debates, scientific and political. There is no avoiding it.

Regards,

'Mann's temperature reconstruction is "controversial", as you state, because claims, not supported by the evidence, were made from it.'

Give me a break, Paul! Mann's reconstruction is only "controversial" because of fossil-fuel-industry-funded people like McIntyre and McKitrick who wish to generate controversy where there is none, doubt where there is none, and confusion amongst ordinary people about whether global warming is really occurring (it is, in fact, if you haven't checked) and whether it is at least largely due to human activities which release greenhouse gases (which has been agreed upon by the IPCC and all major national science academies of the developed world).

As for your point (or lack thereof): 'As for the other nine reconstructions, interestingly, they don't show the Little Ice Age of Midieval Warming Period either!'

They do, in fact, show a LIA and MWP. The pre-1850 record is not a straight line, but one of gradual fluctuations. Post-1850 temperatures start climbing at an ever accelerating rate with the warmest temperature being at the present.

If you can't see fluctuations in the graph prior to 1850, then you are completely unqualified to comment on the graph as you must be blind. Either that or the smog in front of your eyes blocks you from seeing the graph. In that case, I'd say a daily dose of DeSmogBlog would be a proper prescription to remove that hazy vision.

Stephen, I have been getting a daily dose of DeSmogBlog, and not only does it remove my hazy vision, it raises my blood pressure to dangerous levels too! :)

Not to defend McIntyre or McKitrick, you have uncovered evidence they are mere tools of the fossil industry too? Please DO explain! I'm tingly with anticipation.

Interestingly, the National Academy of Sciences gave both of them a respectful hearing, and Mann also. Neither party was completely vindicated, and both were subject to criticism from this prestigious body.

Mann's temperature reconstruction was controversial because solid evidence could not support it's claims prior to the year 1600. Why is that so hard to accept?

Regards,

"Not to defend McIntyre or McKitrick, you have uncovered evidence they are mere tools of the fossil industry too? Please DO explain! I'm tingly with anticipation."

If you only did your research, Paul, you would easily find it.

Ross McKitrick:

http://www.exxonsecrets.org/html/personfactsheet.php?id=1008

Stephen McIntyre:

http://www.exxonsecrets.org/html/personfactsheet.php?id=1007

"Interestingly, the National Academy of Sciences gave both of them a respectful hearing, and Mann also. Neither party was completely vindicated, and both were subject to criticism from this prestigious body."

The NAS is a reasonable organisation and gives everyone a chance to air out their concerns. No surprise there. However, look at the criticisms of McIntyre and McKitrick in Wahl and Ammann and you'll see their results are flawed.

"Mann's temperature reconstruction was controversial because solid evidence could not support it's claims prior to the year 1600. Why is that so hard to accept?"

Not true. Prior to 1600, existing evidence could support the conclusions of MBH. However, not enough evidence was there for the NAS to fully endorse the results. The NAS never discarded the "Hockey Stick," but said that more evidence is needed to confirm the results.

Stephen, I checked out www.exxonsecrets.org. There's nothing there.

Secondly, you don't just ring up the National Academy of Science and expect them to convene some of the world's best scientists simply because you want to air a concern.

You then say:
"The NAS never discarded the "Hockey Stick," but said that more evidence is needed to confirm the results.'

Uh, you can't have "results" until you have sufficient evidence. That is why the claim that the Hockey Stick "proved" that temperatures are warmer now then in 1000 years has been discredited.

Regards,

Wrong, wrong, wrong.

Did you check the links I posted? They show the connection with ExxonMobil.

The claim that the "Hockey Stick" proved that temperatures are warmer than 1000 years ago has not been "discredited" as you suggest, but it has not been confirmed. There is a great gulf between the two.

I won't say anything more because you don't seem to listen or don't seem to care.

Stephen, your links shows nothing. No documentation, no independent verification....nothing!! Just because it's on someone's website doesn't make it true.

Lastly, something that has "not been confirmed" means it is unproven. But the Hockey Stick was presented to the public as if it were factual. That is what many objected to.

Regards,

"Stephen, your links shows nothing. No documentation, no independent verification....nothing!! Just because it's on someone's website doesn't make it true."

You do not have evidence denying this, do you?

"Lastly, something that has 'not been confirmed' means it is unproven. But the Hockey Stick was presented to the public as if it were factual. That is what many objected to."

You said "the claim that the Hockey Stick 'proved' that temperatures are warmer now then in 1000 years has been discredited" though, which is absolutely WRONG! You distorted what the Wegman hearing and the NAS inquiry concluded.

There is a great difference between the claim not being proven and being discredited. On one hand (not proven), the jury is still out, so to speak, while on the other hand (being discredited), the jury would have dismissed all charges.

Further examination is needed to confirm the claim, but existing evidence (of which there is some, you cannot deny this Paul) points to current temperatures being warmer than at any point in the past 1000 years. THIS CLAIM WAS NOT REJECTED, PAUL, ONLY REFERRED FOR FURTHER REVIEW! (Get this through your head!)

Stephen, when the enviro-activists were going around saying "It is hotter now then in 1000 years", they cited Mann's Hockey Stick as PROOF of this claim. Now we find that the proof was lacking.

Possibly I should say Mann has not been discredited; enviro-activists have been, by inflating the available evidence to make unsupported claims.

Regards,

"Stephen, when the enviro-activists were going around saying 'It is hotter now then in 1000 years', they cited Mann's Hockey Stick as PROOF of this claim. Now we find that the proof was lacking."

It may or may not be proven beyond a reasonable scientific doubt (though it has passed the peer-review test), but there haven't been any reconstructions that have passed peer-review tests that have proven the opposite, that the MWP was warmer than today. Wahl and Ammann (below) have concluded that the McIntyre and McKitrick work could not be verifiable.

http://www.cgd.ucar.edu/ccr/ammann/millennium/refs/WahlAmmann_ClimaticChange_inPress.pdf

So, until there is a proper reconstruction which refutes Mann, Bradley, and Hughes, the Hockey Stick will be the benchmark. Also, you neglect to acknowledge that MBH analysed several reconstructions of global temperatures and have graphed them to show the common trend. In other words, MBH is not one sole reconstruction, but an ensemble of several.

If the National Academy of Science had found other temperature reconstructions to be based on more verifiable data pre-1600 then Mann's data, they would have reported that. But they didn't. It may be that all of those reconstructions pre-1600 suffer from weak data.

Another point is that the peer review process has been criticized for not being independent enough.

As for what Wahl and Ammann stated, it appear that the National Academy of Sciences did not agree.

Regards,

The reason the NAS said that MBH could not claim that the last decade was the warmest in over a thousand years was because the data prior to 1600 did not have a decadal resolution to it. To make that claim you would need to have data on a decadal basis which was just not possible with the data they had. All the data which are available shows only a very small increase in temps, during the MWP, over the millenial average and it is obvious to anyone who looks at Mann's and the other data that the last 40 -50 years have been much warmer than 1000 years ago. There are no data except anecodotal reports that the MWP was exceptionally warm. There may have been a slight warming during that period due to a number of factors but nothing like the small band of deniers would like.

EXACTLY. MBH had INSUFFICIENT data to make their "Hottest Decade in 1000 Years" claim. So why did Mann make that claim?

Where did Mann make that claim? Can you point it out for me? Or are you making this up?

Geez Stephen, why are you even asking me to do this work for you?

Michael Mann:

"The specific conclusion published by my colleagues and me that late 20th century Northern Hemisphere warmth is anomalous in the context of at least the past millennium."

http://www.realclimate.org/Mann_response_to_Barton.pdf

If you want more, you can always read the IPCC report.

Regards,

Again, you misquoted Mann. In the letter to Rep. Barton, Mann says the following:

"Studies using these data and methodologies have confirmed
the primary conclusion of our work (e.g. Mann et al. 1998 and Mann et al. 1999) that the most recent decades were likely the warmest of the past 1,000 years for the Northern Hemisphere on the average. The most recent such study (published in Nature) in fact extends this conclusion to at least the past 2,000 years."

You claim he said: "Hottest decade in 1000 years." He actually said "The most recent decades were likely the warmest of the past 1,000 years ..."

You got the time frame wrong, Paul. How is someone to trust your judgment when you cannot even honestly quote a passage from a document?

Misqoute? Where? That you object to Mann's exact words demonstrates a remarkable lack of objectivity Stephen.

Look at Mann's graph. Which is the hottest decade? 1990? Now will you accuse people of not viewing his graph correctly?

Mann's 1000 year claim is not sufficiently supported by the data. Now it goes back 2000 years? How weak is this data?

Regards,

"Misqoute? Where? That you object to Mann's exact words demonstrates a remarkable lack of objectivity Stephen.

Look at Mann's graph. Which is the hottest decade? 1990? Now will you accuse people of not viewing his graph correctly?"

A graph (or any other presentation of data) is not someone's actual comments. He never explicitly said that the 1990s was the hottest decade of the past 1000 years. Therefore, your claim that he claims that the 1990s were the hottest 10 years over the past 1000 years is refuted unless he actually said this in the paper.

I will not accuse you of not viewing the graph correctly, for it is obvious that the 1990s was the warmest decade in 1000 years. (THERE! I SAID IT!) There may have been INDIVIDUAL YEARS in the MWP which were warmer than individual years in the 1990s. (The year of the Pinatubo eruption in 1991 or the following year may be one that was topped by a MWP year like 1043 or 1067. Who knows for sure, though, since resolution of the record is not that high back then.) However, by decadal average temperatures, it is highly unlikely that any 10-year span in the MWP was warmer than the 1990s.

Re: 'Mann's 1000 year claim is not sufficiently supported by the data.'

This may or may not be true. However, his claim cannot be refuted by any study which passed the peer-review test. The MBH study is the best we've got, bar none, and it is entirely justifiable that the IPCC wishes to use it rather than the flawed approach of M&M (which was blasted to smithereens by Wahl and Ammann).

Non, Sylvain. Ce n'est pas vrai.

Deniers in the case of AGW have their heads so deeply buried in the sand that they can't hear or see the facts presented by climatologists, oceanographers, and other scientists. These deniers are not Galileos by any stretch of the imagination. They are ideologues, intellectual dinosaurs, or worse, have a stake in the continuation of the status quo.

Stephen,

You seem to be casting this argument into the form of a black and white choice. In other words, either A or B is true and no other choice is possible.

If you are dealing with choices like M. Kopernik faced, then it is black or white. Either the solar system revolves around the earth, or it revolves around the sun. These were the key issues of his times, although we now know that this is an oversimplified view of the cosmos.

In the case of climate change, the issue is not black and white. The question is not whether man has influenced global climate, but rather by how much man has influenced the climate. Man's influence on the climate is clearly not zero, nor is man responsible for all climate change. The truth lies somewhere in between.

"Man's influence on the climate is clearly not zero, nor is man responsible for all climate change. The truth lies somewhere in between."

This may be true. However, the deniers to which Sylvain and I refer do not believe that increased CO2 levels caused by human activities have anything to do with the enhanced greenhouse effect. They do not consider CO2 to be a pollutant. CO2 at natural levels (i.e. the c. 275 ppm range before 1850) is not a pollutant. However, at the levels we are emitting into the atmosphere, it can be considered pollution, since it is hazardous to the health of the planet and detrimental to life (including our own).

An excellent explanation and description of the term "pollutant" and examples of pollutants can be found here:

http://en.wikipedia.org/wiki/Pollutant

Deniers believe that our impact on the climate system cannot be much more than a few percent as they try to persuade people that the planet is so large and we are so small.

However, they are deliberately misleading the public. The atmosphere is very thin, and as we are numerous, we can and do contribute vast amounts of CO2 to the atmosphere which shifts the balance out of whack.

True climate scientists like Drs. Weaver, Mann, Hansen, Schneider, and Santer who have a significant publishing history have found out the facts. Our activities are having a significant effect on the climate system. Deniers refuse to listen to reason and to the real science.