This is a very cool site. I am bookmarking it right now

Agriculture has had the concept of Leibig’s barrel (Law of the mMinimum) for almost two centuries: http://en.wikipedia.org/wiki/Liebig%27s_barrel

Simply, this concept says that the rate of growth of plants will be dictated by the minimum resource available to it at that time. It appears that Mann et al have made the assumption that temperature will have been the minimum resource for the entire span of the life of the trees that they selected.

If you have a total sample population where it does not appear that temperature is the minimum resource for most of those plants over the past century, then it is clear that there must be at least two potential resources that could control growth rates over the life of a plant. In reality, there are probably many more than two, including precipitation, temperature, nutrients, light, wind etc.

If they elect not to use the entire population, then they have to do some heavy duty number crunching to show statistically that these twelve trees should be expected to always have had temperature as the controlling minimum factor. Personally, I don’t really see how they could isolate out enough factors to conclusively show that for a millenium.

It appears that Mann et al have been victims of the same recency bias that has cause so many problems in the finacial sector where they have assumed that recent data during a period where there was surface temperature data available is both predictive of the future and is more important than older information.

[IMG]http://i939.photobucket.com/albums/ad234/Patriot_Vet/RealClimate/RealClimateScreenshot.jpg[/IMG]

http://i939.photobucket.com/albums/ad234/Patriot_Vet/RealClimate/RealClimateScreenshot.jpg

[IMG]http://i939.photobucket.com/albums/ad234/Patriot_Vet/RealClimate/RealClimateScreenshot-AfterModer-1.jpg[/IMG]

http://i939.photobucket.com/albums/ad234/Patriot_Vet/RealClimate/RealClimateScreenshot-AfterModer-1.jpg

[IMG]http://i939.photobucket.com/albums/ad234/Patriot_Vet/RealClimate/RealClimateScreenshot-AwaitingModer.jpg[/IMG]

http://i939.photobucket.com/albums/ad234/Patriot_Vet/RealClimate/RealClimateScreenshot-AwaitingModer.jpg

[IMG]http://i939.photobucket.com/albums/ad234/Patriot_Vet/RealClimate/RealClimateScreenshot-AfterModerati.jpg[/IMG]

http://i939.photobucket.com/albums/ad234/Patriot_Vet/RealClimate/RealClimateScreenshot-AfterModerati.jpg

I am supplying the direct link, as well as trying to post the pictures directly.

No expletives or imputations used – simply arguing the data, and yet the posts are still deleted or not even posted.

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The process above is doing no more conceptually than calibrating a series of thermometers at the end of an experiment and then using only the records from those thermometers in calibration as a valid reflection of the thermal history of the experiment.

Except that thermometers behave in a predictable way – the same cannot be said of tree rings. How can anyone be even vaguely sure that a tree behaved in the same way hundreds of years ago, when conditions may have been very different, to the way it behaves today with respect to temperature?
If you can’t use most of the proxy data then you shouldn’t use any of it.

There is a temperature record for a few hundred years. If it is assumed to be representative of the actual growing temperature during the growing season then picking trees that exhibit growth patterns that mimic the temperature is not cherry picking. You are picking trees that grow in tune to the facts and rejecting others that have grown otherwise (water, minerals, depth of soil, tree age, have changed the growth pattern and they do not match the temp record. In the extreme should you also include trees that have died early = zero growth?!)

I may well be mistaken here but I assume that the trees on record are not growing for the complete period of 2000 years? If each tree is just a short record then would you suggest that the matching of ring growths on progressively older/preserved trees is cherry picking. I have always assumed that the record can only be extended back in time by matching growth patterns in different samples from similar area. I assume that trees that have badly matched patterns are not used – I’m sure you would agree that this is a valid action?. Isn’t this the similar to only using trees that match known temperatures and discarding the rest.

The UK has very strange defamation laws. If you are accused of defamation you are guilty until you prove your innocence in a court of law= ££££££s. To initiate the case costs a mere £1700

All blogs message boards etc. have to be aware of this else vast sums of money can change hands – from the author, and if the blog/newspaper publisher does not remove the offending text completely, from the publisher mainly to the hands of barristers/lawyers etc.

Using a psuedonym is no safeguard as your ip address is recorded and can be extracted from the publisher and your name and address from your ip provider at no cost using something called a “norwich pharmacal”.

If your messages implied/stated falsification, incompetance, or otherwise denigrated the authors then the publisher would be forced to act to protect itself. There is a really good case to look at – smith v advfn for an example.
http://www.bailii.org/form/search_multidatabase.html and search advfn.

Take care!

From the links above, it appears Briffa used this profile of temperature change throughout the year.

http://rstb.royalsocietypublishing.org/content/363/1501/2269/F6.large.jpg

But there are other temperature profiles in the links which don’t show anything particularly special is happening – summer or annual.

http://rstb.royalsocietypublishing.org/content/363/1501/2283/F10.large.jpg

http://rstb.royalsocietypublishing.org/content/363/1501/2269/F1.large.jpg

http://rstb.royalsocietypublishing.org/content/363/1501/2283/F8.large.jpg

And then there is this profile of the number of trees and the resulting temperature index from three different datasets.

One can see which dataset was chosen – hint, the one in the middle with the hockey stick.

http://rstb.royalsocietypublishing.org/content/363/1501/2269/F3.large.jpg

She does note “The details are on the last three days of Steve McIntyre’s site Climate Audit, and summed up beautifully on Watts Up,” but I think her post is a good one to pass on to the general public. Those interested will be here soon enough.