IPCC changed viewpoint on the MWP in 2001 – did this have effect on scientific results?
Guest post by Frank Lansner Latest News (hidethedecline)
A brief check indicates a “warm MWP-consensus” before IPCC published the Mann hockey stick graph in 2001. But after 2001, results on MWP seems to approach the IPCC viewpoint.
In April 2009 I collected a series of results concerning Holocene, Historic and recent temperatures for an article on WattsUpWithThat.
Here I found approximately 54 datasets (almost 100% peer reviewed results) that I used for analyzing the claimed difference on MWP on the Northern vs. the Southern hemisphere. I also used the 54 datasets to see if the tree ring method has an impact on MWP results.
Another aspect of MWP results caught my interest:
fig. 1.
It is often debated how IPCC changed its viewpoint concerning the Medieval Warm Period in 2001.
– Was the pre-2001 MWP viewpoint simply “wrong” ?
– When IPCC launched their new viewpoint on MWP in 2001, was this new viewpoint in fact the consensus in 2001?
– Or did the IPCC actually claim to know better than the consensus in 2001?
– What is the consensus on the MWP today?
– And finally, did the results after IPCC change of viewpoint in 2001 have changed, how can this be explained?
Here are the 54 temperature datasets covering the MWP divided in two groups :
1) 1976-2000 vs 2) 2001-2009
fig. 2. (Geographical origin see)
First we see that both 1) and 2) shows the MWP was warmer than today. (This is partly due to my criteria for the 54 datasets: Max 15% tree ring data, due to possible problems with tree ring data and thus a need to see data not dominated by this one method. Quite a few of the excluded tree ring data are frequently used by the IPCC, yielding the well known hockey shapes from IPCC AR4, 2007.)
Second, we see a MWP for group 1) 1976-2000 more than twice as warm, compared to recent years, as the group 2) 2001-2009. A significant and surprising finding. The distance between 1) and the IPCC hockey sticks, with all the tree graphs of recent years, is even bigger.
One might argue that the data choice for my Watts article was not quantitative, fully exact, etc. But I simply cannot come up with any explanation for such a big change in the trend of results when just dividing by the year of publishing. Therefore I will assume that there is in fact a development in the results regarding the MWP after 2001.
Further, if you compare graph 1) 1976-2000 on fig. 2 with the original temperature graph IPCC 1990-2001 on fig.1., you will see a stunning match. This indicates that the consensus of a WARM middle age before year 2001 was likely to be a real consensus. If true:
How could the IPCC publish the hockey stick in 2001 and ignore the consensus at the time?
Several results came later that confirmed the IPCC’s 2001 Opinion: Hockey sticks, mainly tree lines. But how could the IPCC know what the future results on the MWP would be?
If the conclusions of “climate gate” are even remotely true, then this would explain that the IPCC controlled the future results.
Just a thought: I suppose tree-ring proxies were selected because Mann et al understand that the best hockey sticks are still made of wood…?
🙂
“but… could IPCC see the future? Or how could IPCC know what future results on MWP would be?”
Of course they can see into the future because they set the ground-rules.
If the IPCC claimed that CO2 was responsible for global warming through the stimulating of magical fairy-dust, then no doubt a whole series of sycophantic researchers would use some undisclosed statistical techniques based on unpublished raw data to support the hypothesis.
The late John L. Daly’s blog contains a very good history of the disappearance of the Medieval Warm Period, and includes as figure 1. the graph showing the MWP and the Little Ice Age that appeared on page 202 of the 1990 assessment.
J T Houghton, G J Jenkins, J J Ephraums, Eds,, “Climate Change; The IPCC Scientific Assessment”. 1990 . Cambridge University Press, p.202
http://www.john-daly.com/hockey/hockey.htm
What happens if you plot MWP temperature versus date of publication of the study?
Are there two ‘clumps’ pre- and post- 2001.
Incidentally, even the ardent alarmist James Burke recognized the MWP, from Connections, talking about Old English life, ‘If all this sounds painfully chilly to the modern reader, it should be remembered that the average temperatures of northern Europe were several degrees higher than they are today.’
Original approach, good work, surprising result … or not so much.
And a good headline. Yes, they tried hard to ‘disappear’ it.
Almost worked, but not anymore. Tough times ahead for them.
Keep in mind that most of the present warming has been shown to be due to higher winter and night time temperatures, not growing season daytime temperatures. This may be also true for previous periods of greater average warmth. One might expect the temperatures being higher at times other than growth times might result in much less added growth than with hotter growth time. Also, If the daytime growing season were warmer, the rainfall may also be lower (or if higher, associated with more cloudiness and thus decreased Solar insolation). This is a negative correlating factor. One or both of the two effects may be the cause of subdued or different response of tree rings compared to more valid proxies.
Mann, the science rat, has been cornered. Now comes his counter-attack.
http://online.wsj.com/article/SB10001424052748704187204575101461287544470.html
Frank, a very enlightening approach to show the misinterpretation of science by the IPCC, congratulations!
I think there were some ClimateGate e-mails where Mann et.al. talked about the need to disappear the MWP. They would fit in nicely with your article.
The headline may be non-standard english, but you can’t blame that one on so-called “ebonics”. It’s seems more like criminal (mobster) derived jargon, which in a way is quite appropriate considering that AGW is the ultimate protection racket.
Anthony,
This posting on an alternative proxy using shells is interesting. I am not sure if you have that. The graphing is useful.
http://bishophill.squarespace.com/blog/2010/3/9/a-new-type-of-proxy.html
Also for interest, where I live in the UK (Wrotham pronounced Rootam) a grape variety from the Roman period was found growing near a wall it was then cultivated and exported and became known as Wrotham Pinot Noir. You can buy the wine in the USA.
http://www.richardgrantwine.com/news.html
Given that the Medieval Warm Period was probably warmer than now, is repeatedly mentioned in art and literature from the period and was, to the best of my knowledge, responsible for the spread of vineyards as far north as York (not generally considered to bethe warmest city in Christendom) how precisely did we/the IPCC/the press/Al Gore, etc let them get away with hiding it?
There’s a very ugly truth apparent here – at least, it is the only way I can read Lansner’s evidence.
(1) IPCC flout the true consensus and present the outliers.
(2) they tout them as “consensus”: a big lie.
(3) they pressurize researchers to reinforce the lie.
Here’s Canada Free Press
In order to carry out the IPCC’s mandate to show a human cause for global warming, Dr. Jonathan Overpeck of the University of Arizona and one of the lead authors of the IPCC reports sent an e-mail to fellow researcher Dr. David Deming of the University of Oklahoma stating that:
“we have to get rid of the Medieval Warm Period.”
Dr. Deming, maintaining his scientific ethics and professionalism, refused to alter his data to “get rid of the Medieval Warm Period.” However, Dr. Michael Mann rose (sank) to the challenge. In 1998 he, along with co-authors Bradley and Hughes published the now famous “hockey-stick curve” that did just that.
I seem to remember Dr Deming was pushed out of his job last year.
For what it’s worth, I like the title. If the grammatical incorrectness connotes a lack of education, then that’s analogous to the IPCC, where most authors are not actually climate scientists.
I have a vague memory that it was necessary to get rid of the MWP because the AGW theory had CO2 raise the temperature to a “tipping point” at which water vapor became the dominant and destructive green house gas. The pre 2000 MWP data showed temperatures above the “tipping point”. It was a problem to explain why positive water vapor feedback didn’t wipe out mankind then but it would this time.
The AGW models proved that there could not have been a MWP, if there had been we would not have survived. The next problem was to find data to support the proof. Clever scientists did it.
“R. Craigen (10:18:22) :
The most salient feature of the spaghetti graph of 54 datasets is the wild variety of time series available as ’scientific’ proxies. The immediate consequence is inescapable: by selecting which proxies to use, it is possible to tell practically any story one likes about the late Holocene temperatures.”
This is true.
However… 🙂 In my case I made the main article on Watts last year. And obviously I did not select data series with some kind of criteria on the year the data was published. In that sence these 54 datasets are really random (also) when considering publishing year. And therefore the huge difference in trends before and after 2001 appears significant and real. Otherwise I would never send to Anthony.
My wish is, that this would be investigated further. Why?
If my findings are true, this is a huge blow to the IPCC.
The thing is, IPCC should be NEUTRAL.
But if IPCC has promoted some specific viewpoint in 2001 on this essential matter, how could they get out of this one? How can IPCC “know” better than the consensus?
All this this talk about “consensus” and then IPCC acted against the consensus? Not good!
So i hope you super scientist on WATTS will take this lead and take it further.
OT. I can already see Al Gore receiving another Nobel Peace Prize for this
http://news.bbc.co.uk/2/hi/technology/8560469.stm
RockyRoad (10:00:28) :
Maybe we can “disappear” the IPCC! What a great thought
“He who asks God and asks for a little is a fool”…so, be more ambitious, disappear the UN!
-Another thing: I actually did the opposite than exaggerating the problem.
Since I did not use several tree-ring data (mostly after 2001) , the difference between 1976-2000 and 2001-2009 is VERY likely to be bigger than what I have shown.
This post needs some proof reading, there is some rather tortured English.
>And finally, did the results after IPCC change of viewpoint in 2001 have changed, how can this be explained?<
I can't get the thrust of this at all.
OT but AccuWeather’s Bastardi predicts an increase in hurricanes hitting the US in 2010: http://www.foxnews.com/weather/2010/03/10/hurricanes/
“If the conclusions of “climate gate” are even remotely true, then this would explain that the IPCC controlled the future results.”
This is a joke post right?
By the by – the 1990-2001 plot is of data for a small bit of Europe, not the Northern Hemisphere. Hence the MWP looking less of a feature in later plots – because the evidence for the whole Northern Hemisphere is that the MWP was rather less of a feature than it was in a small bit of Europe.
Where have all. The warmings gone Long time passing Where have all the warmings gone Long long ago Where have all the warmings gone Gone to hockeysticks every one When will they ever learn When will they ever learn. New verse to old song?
R. Craigen (10:18:22) :
I believe the past practice has been to take proxies that fail to explain historical records as more suspect than proxies that do explain them. In other words, those that don’t correspond to verifiable facts of history have critical flaws. Thus, a proxy that indicates warming during a period in which winters were unusually long, summers short, to the point of causing hemisphere-wide crisis (as during the LIA) must be considered unreliable. It is this breach of the obvious criterion of cross-correlation between “facts” that shows how far “climate scientists” have fallen. Science unhinged from reality is not science, but religion.
This was the real motivation behind “Mike’s clever trick” to “hide the decline”. It was done not to preclude any suggestion of declining temperatures in the present, but to conceal the “divergence problem” that revealed the complete inadequacy of proxies constructed to minimize temps in the MWP.
I continue to be incredulous that there is a controversy over the MWP. As a student, long ago, I took a course in Scandinavian literature and the first semester was devoted to the medieval Icelandic writings. Not just the sagas cited below, but especially “Njal’s saga” which describes conditions in Iceland a couple of hundred years after the era of exploration, written by Snorri Sturleson, and a compelling drama in itself.
Among the required readings were the saga of “Eric the Red,” finder of Greenland (voyaging from Iceland), and “Leif the Lucky,” his son, who set out from Greenland and explored the coast of North America. Keep in mind these folks were crossing the usually stormy North Atlantic in open boats of 40-70 feet in length. Try doing this today, even in Summer!
Leif’s report on North America included, among many other things, references to the grapes (Vinland) and hostile Amerinds, hostile enough that settlement attempts came to nought. There is archaeological evidence in the form of excavated Viking sites to confirm this attempt at settlement.
It’s important to know that in 1000CE, Iceland was (and perhaps still is) the most literate society on Earth. Do warmists actually believe that Eric and Leif were making these stories up? Apparently they do, or else chose to ignore the clear facts of the matter. Talk about inconvenient truths!
The rest of the Icelandic literature of the period portrays an Iceland far more benign than the present. How could those medieval Icelanders have anticipated the present need of skeptics for evidence of the MWP?
There is no need of “proxies” to elucidate the climate of a thousand years ago when there is a substantial writen record to confirm it. Nor is the written record confined to Icelandic literature.
Nor is there any need for skeptics to ‘prove’ that the MWP wasn’t a strictly Northern Hemisphere phenonomen; it is rather a task for the warmists to prove that it was; unfortunately for them, there is no comparable literature available from the southern hemisphere at the time, lacking as it did any society capable of written records.
That said, it has long been clear that the MWP is critical for a popular resolution of the current argument:
If the MWP was real, then certainly the climate was warmer then than now and, while the present situation may be warm, it is hardly outside the bounds of natural climate variability. If the MWP is a chimera, then we should take warmist alarmism seriously. If the MWP was real, no one can argue that its occurence had anything whatever to do with atmospheric C02. Game, set, match.
But, “we don’t need no stinkin’ proxies” where we have the written records of people of the time who had no reason to misrepresent the truth.
It continues to amaze me that folks, who should know better, ignore the historical record and rely instead upon purveyors of the cause “du jour” to form their opinions. Speaking for myself, I’m prepared to let the resolution of the warmist theory to stand or fall on the reality of the MWP. L