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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Christoffer Bugge Harder (12:53:23),
Michael Mann deliberately erased both the medieval Warm Period and the Little Ice Age. When he was repeatedly asked for his data and methodologies, he stonewalled.
If you weren’t such an apologist for Mann’s rewriting history, you would see what he’s doing, and why. Being an enabler for Mann’s pathological science doesn’t pass muster here.
@PhilJourdan
The PSU inquiry did in fact address that Mann had engaged in fabrications, falsification or suppressions of data wih respect to his entire work – including the Hockey Stick (MBH 98/99).
And the NRC did conclude that the biases of the statistical method used by Mann were “small in effect” and did not affect the outcome. The major issue was the inclusion of proxies.
The (non-peer reviewed) Wegman report dealt only with the statistical issues and failed to notice that these did not affect the outcome (as stated above). Besides, the criticisms about the non-centered PCA has subsequently been dealt with by Rutherford et al. – and the criticism with respect to the 1901-80 normalisation by Wahl & Ammann. Again, both found these to be non-issues with respect to the conclusions of MBH 98/99. Go read them for yourself if you doubt what I say.
P.S. Mr. Watts: I wrote a longer comment to Frank with many of the same points which I found very precise, polite and non-venomous – could you be kind to see if it has been lost in the spam filter?
REPLY: I don’t see it there. I’m sorry, you are welcome to resubmit. – Anthony
Smokey,
all you you do is simply repeating the classical claims and accusations which have already been debunked on multiple occasions in the sources given here – the NRC report, Rutherford et al., Wahl & Ammann and recently the PSU inquiry. Here is another nice summary for you:
http://www.logicalscience.com/skeptic_arguments/fakeddata.html
The data and metodology of MBH98/99 has been freely available for quite a few years:
http://www.nature.com/nature/journal/v430/n6995/suppinfo/nature02478.html
– and so far, nobody has succeeded in supporting any of your claims scientifically. But since you are so confident that they must be true, then why do not you go there and knock yourself away with the data + the methods? Surely, there is a high profile Nature or Science publication waiting for you if you are able to demonstrate what McIntyre, NRC and the entire scientific proxy community has hitherto failed in demonstrating.
To be sure, I am under no illusions that any factual documentation, evidence or judicial findings is likely to change your mind about Mann, just like the inquisitioners of Dreyfus remained unconvinced by any evidence to his innocence even after his exoneration. However, I do have the the vain hope that this page might harbour a true sceptic or two who would be interested in the facts. Surely you know the proper terminological label for the kind of scepticism which cannot be dissipated by whatever evidence or documentation?
@Mr.. Watts,
I see it now (17/03, 12:53:23). Apparently, it just took a while for it to surface. I jut did not see it with the usual note “awaiting moderation” upon submission, so I thought that it had become lost. Do not be bothered.
@CBH – The PSU inquiry was for his work at PSU only, not his work at UVA (when he concocted the Hockey Stick). And again, you seem to be agreeing with me on the NRC review as it was not a rebuttal of M&M, but merely whitewashing the results of the Hockey stick based upon the data supplied (not the method). The M&M review of MBH98 called into question the very method used.
CBH:
I asked you here and before, quite simple:
”
Can you explain why Mann overfokus on Bristlecones, one area of the NH and then claims results to be NH?
Can you explain why hia computerprogram was made to output hockey stick almost never mind what real data was used as input?
Can you explain why Briffa claims that Sibieria too had a temperature hockey stick just from a few individual trees?
”
I still havent got your explanation. And it puzzles me because you believe you have the best sources of information etc. So use them and come back with an explanation.
If you cant, then stop using Mann, Briffa and those who rely on Mann and Briffa as valid data sources. If you continue without actually being able to defend their methods, to me it seems like you have agenda rather than a wish to seek truth.
Rutherford:
“If your experiment needs statistics, you ought to have done a better experiment.” – Lord Ernest Rutherford
http://wattsupwiththat.com/2010/03/20/science%e2%80%99s-dirtiest-secret-the-%e2%80%9cscientific-method%e2%80%9d-of-testing-hypotheses-by-statistical-analysis-stands-on-a-flimsy-foundation/
Goes for Mann data for example:
http://www.klimadebat.dk/forum/vedhaeftninger/mannaverage.jpg