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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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.)
Which is more important? MWP or funding?
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.]
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.
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.
The three different lines on the graph show that the science obviously isn’t settled.
Said, Keith Briffa of the CRU:
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
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.
“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
“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.
Apparently the MWP was not “statistically significant.”
Unlike GCMs which consistently do worse than a coin toss.
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!
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.
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.
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.
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.
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….
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:
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
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!”
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.