When the IPCC 'disappeared' the Medieval Warm Period

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.

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woodNfish

Who is responsible for that tortured headline? Please use proper English, the dumbed-down ebonics nonsense is disgraceful. (Yeah, I know “dumbed-down ebonics” is redundant.)

Steve Goddard

Which is more important? MWP or funding?

Ken Hatfield

This is really nice work. Can you go back through it and clean up the English so I can forward a link to my brother the warmist?
[Reply: Frank Lansner’s first language is not English, and he does a great job under the circumstances. I’ve cleaned up some of the syntax. ~dbs, mod.]

woodNfish

Frank Lansner: “I found approximately 54 datasets (almost 100% peer reviewed results)”
Thank you for the article, Frank, but surely you know that peer review is a meaningless process in climate science. I even hate to call this sham a science anymore. To me, it is totally discredited – all of it.

Dave Wendt

I recall reading somewhere a while back that in the pre IPCC days the common nomenclature was to call it the Medieval Climate Optimum. There seems to be a move afoot to again reclassify it as the Medieval Climate Anomaly. These folks seem to be devotees of the Sapir-Whorf theory that language defines thought.

H.R.

The three different lines on the graph show that the science obviously isn’t settled.

sHx

Said, Keith Briffa of the CRU:

“I know there is pressure to present a nice tidy story as regards ‘apparent unprecedented warming in a thousand years or more in the proxy data’ but in reality the situation is not quite so simple. … I believe that the recent warmth was probably matched about 1,000 years ago.”
http://www.eastangliaemails.com/emails.php?eid=138&filename=938031546.txt

Whenever I hear about the Medieval Warm Period, this candid assessment in one of those liberated emails comes to my mind. That, and Micheal Mann’s re-discovery late last year of the MWP and his immediate attempt to rename it ‘Medieval Climate Anomaly’.

I put together an interesting comparison of Mann & Jones (2003) vs. Esper (2003), Moberg (2005) and Alley’s 2004 d-18O temperature record for Central Greenland…
Mann (2003), Esper (2003), Alley (2004) and Moberg (2005)
Only one of these four reconstructions is missing a Medieval Warm Period… Mann & Jones.
Esper and Moberg coauthored a paper on the differences between the Hockey Sticks and the correct reconstructions in Quaternary Science Reviews in 2005…
Climate: past ranges and future changes

So, what would it mean, if the reconstructions indicate a larger (Esper et al., 2002; Pollack and Smerdon, 2004; Moberget al., 2005) or smaller (Jones et al., 1998; Mann et al., 1999) temperature amplitude?
We suggest that the former situation, i.e. enhanced variability during pre-industrial times, would result in a redistribution of weight towards the role of natural factors in forcing temperature changes, thereby relatively devaluing the impact of anthropogenic emissions and affecting future predicted scenarios. If that turns out to be the case, agreements such as the Kyoto
protocol that intend to reduce emissions of anthropogenic greenhouse gases, would be less effective than thought.

AGW Crunch time.
Anthropogenic Global Warming depends and rests entirely on one single premise.
That “greenhouse gases” alone (at no more than 1% of all the atmospheric gases) are responsible for all atmospheric temperature.
The assumption requires that oxygen and nitrogen (at 99% of all atmospheric gases) absorb no heat whatsoever.
It also requires that CO2 (0.0385% of atmospheric gases) is the primary driver of temperature in the atmosphere and that at a certain temperature, a positive feedback loop involving water vapour becomes activated by CO2 warming.
So to settle AGW debate should be and oddly is, a very simple and straight forward thing to do.
If it is possible to show that this premise is false then AGW is debunked.
Firstly we must ask, is it possible for the latent heat of one substance at 0.0385% of the entire atmosphere, or even several substances at no more than 1%, to be responsible for the assumed estimated atmospheric temperature of 33º C ?
Secondly, is it really at all possible that oxygen and nitrogen are, as the so called climatologists and AGW proponents claim, transparent to radiant heat ?
Thirdly is it possible to answer point one and two with simple reproducible experiments ?
The answers are NO, NO, and YES respectively.
We can resolve the first question with a simple thought experiment as follows:
Is it possible to heat one liter of fluid by 33º C, be it gas or liquid, with one centiliter (1% of 1 liter) with boiling water or steam ?
Answer, a resounding NO.
The second question can be answered just as easily:
How does ordinary air (20% oxygen and 79% nitrogen) compare to pure CO2 with regards to heat absorption ?
The answer can be found here: “AGW Debunked for £3.50”,
and is further verified here: “The Heat Capacity of gases”,
The only conclusion you can draw from this, is that AGW is indeed a fraud.

JDN

“Disappeared” is soviet-era speak. “Speak” is Orwellian speak. Lot’s of non-ebonic cultural references in that headline.

WHOA !!!!!!!!!!
Talk about a spagetti graph !!!!
The MWP, now you see it, now you don’t.
Serious “groupthink” going on there

Steve Oregon

“How could IPCC publish the hockey stick in 2001 and ignore the consensus at the time?”
Just imagine the excitement when they first viewed the “Hockey Stick” and how they imagined it would serve them.
Knowing how usefull the much louder alarms could be the changing of their MWP position was too easy.
The rest is RealClimate science.

Steve Goddard

Apparently the MWP was not “statistically significant.”
Unlike GCMs which consistently do worse than a coin toss.

TerrySkinner

It seems to have taken some time for it to sink in with the warmist community of how important is was to minimise earlier non-human climate fluctuations. Use of the word ‘unprecedented’ in relation to warming at the end of the 20th century, particularly with reference to the 1998 event was no doubt closely followed by this downgrading of the MWP and LIA.
It may be that this was a group think response to early sceptic responses to the ‘unprecedented’ late 20C warming, i.e. pointing out that it was certainly not unprecented. Very much an ‘Oh yes it was, so there!’ sort of response.
We have seen similar more rapid responses to recent warmist problems: Cold winters, lots of snow, non-melting glaciers, extra Antarctic ice, few hurricanes. The forthcoming AGW stuff will show how unimportant such evidence really is in the face of the dire threat…blah, blah, blah.
A good example perhaps of rewriting the peer reviewed literature!

richard verney

The historical evidence for the MWP in the NH is overwhelming and even Phil Jones accepts that in the NH, temperatures were hotter than today. The only issue is the SH where there is less proxy data (and we all know how unreliable proxy data is) and where there is less recorded history. What would be interesting is for AGW to explain what climate model permits a MWP in the NH but not on a global scale. What is the mechanism at work that caused the NH MWP? I have never heard any convincing explanation as to how this could have been caused.
The MWP and RWP are real problems for the AGW argument since at least as far as the NH is confirmed the historical evidence for these eents is overwhelming and they are unable to explain these events. Further, there is no evidence of mass specie extinction (polar bears were not wiped out) and mankind flourished. All the historical evidence suggests that man flourishes in a warmer climate and this that global warming woyuld be a good thing at least for the NH.
Against this backround, it is no surprise that the IPCC have had a revisionary approach to history so as to down play the MWP since without such a stance they cannot assert that tenmperatures are unprecedented etc.

RockyRoad

Maybe we can “disappear” the IPCC! What a great thought!
BTW, I actually like the title of this thread. It shows originality and absolutely nails the process used by the IPCC–in this case, “disappear” is their operatve word.
And I agree completely with Frank Lansner when he says “I even hate to call this sham a science anymore. To me, it is totally discredited – all of it.”
The more I study “climate science” and listen to revealing comments by folks like Phil Jones, the more my head spins.

richard verney

O/T and I know that weather does not = climate but Majorca has been hit by snow storms, the worst in 50 years. See Daily Mail article:
http://www.dailymail.co.uk/news/worldnews/article-1256974/Shock-British-holidaymakers-Majorca-island-hit-freak-snowstorm.html
An elderly man complains that in Barcelona, they have been without electricity for 24 hours and has never experienced such cold, even during WW2. This would have been the position in the UK if we had been reliant upon renewable energy for our power. This winter, for the best part of 2 weeks, due to the lack of wind, wind farms were generating only about 3 – 8 % of their rated output such that everyone in the UK would have been without electricity for more than 20 hours per day. Millions would have died since electricity is needed even for gas or oil powered central heating (eg., to run the circulating pump etc). The UK government needs to dramatically rethink its energy policy before it is too late.

TomLama

For our ‘English’ teachers among us. Lighten up!
The ‘disappeared’ reference has deeper meaning that your ‘deep thoughts’ allow you to perceive. Alas, dimbulbs rarely get the ‘point.’
As Bob Hope put it: Allah has chosen to dim your lights.

David

Steve I suspect the excitement of first viewing the hockey stick was akin to Dr Frankenstein’s on seeing his monster come to life as planned….

Vincent

Politicians,
“The only conclusion you can draw from this, is that AGW is indeed a fraud.”
It is indeed a fraud, but some of your figures are a bit suspect.
You write “Firstly we must ask, is it possible for the latent heat of one substance at 0.0385% of the entire atmosphere, or even several substances at no more than 1%, to be responsible for the assumed estimated atmospheric temperature of 33º C.”
The “assumed” atmospheric temperature as a global average is generally taken to be about 15C not 33C. Are you referring to the estimated GHG warming which has been assumed to be around 33C? It should be remembered that 90% of GHG warming comes from water vapour not from CO2.
Your other remark, that latent heat of CO2 being responsible for the warming is incomprehensible to me. Latent heat is the heat involved when a substance changes to a different state of matter. The GHG effect is supposed to be due to absorbtion of infra red radiation and has nothing to do with latent heat.

This is just one of numerous examples where the IPCC picks out the research paper that tells the story the IPCC wants to tell, and ignores all the rest of the papers. Other examples of this behavior include
* The antarctic sea ice story recently discussed at WUWT.
* Sea level rise
* Greenland ice sheet
* Tropical cyclones
* UHI
* Past levels of CO2
* Solar activity
Of course, post-climategate we now know the IPCC strategy even more clearly:

I can’t see either of these papers being in the next IPCC report. Kevin and I will keep them out somehow – even if we have to redefine what the peer-review literature is !
Cheers
Phil

See this link for a review of the CRU emails related to the MWP: http://www.appinsys.com/GlobalWarming/UnprecedentedWarming.htm
Also, the IPCC red herring that the MWP was not global: http://www.appinsys.com/GlobalWarming/MWP_Globality.htm

geo

I suspect that the lack of accuracy of dating multiple proxies from around the world is a significant culprit in the “disappearance” of the MWP. If you have two sine curves that should be matched up in time, you get a very different picture than if you mismatch the timeframes –they’ll tend towards cancelling (or at least minimzing) the overall impact in the latter case.

TomLama (10:07:22) :
“For our ‘English’ teachers among us. Lighten up!”

It’s a damn poor mind that can only think of one way to spell a word.
~President Andrew Jackson

R. Craigen

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.
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.

R. Craigen

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…?
🙂

KeithGuy

“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.

Jim Berkise

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

ZT

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.’

jaypan

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.

Leonard Weinstein

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.

Paddy

Mann, the science rat, has been cornered. Now comes his counter-attack.
http://online.wsj.com/article/SB10001424052748704187204575101461287544470.html

DirkH

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.

Justa Joe

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.

cloud10

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

richard

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.

TA

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.

Allan J

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.

Frank Lansner

“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.

Richard deSousa

OT. I can already see Al Gore receiving another Nobel Peace Prize for this
http://news.bbc.co.uk/2/hi/technology/8560469.stm

JonesII

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!

Frank Lansner

-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.

Nick Good

This post needs some proof reading, there is some rather tortured English.

Nick Good

>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.

RockyRoad

OT but AccuWeather’s Bastardi predicts an increase in hurricanes hitting the US in 2010: http://www.foxnews.com/weather/2010/03/10/hurricanes/

Jay

“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.

Richard Graves

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?

Dave Wendt

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.

L

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