Dendroclimatologists look specifically for trees hypothesized to be non-moisture limited. This is usually based on observations of the terrain the trees are located. Often but not always they will then use statistical correlation to temp to demonstrate whether they are correct and throw away the rest (very bad science).

There is no demonstration or verification of linearity, no demonstration that trees are responding to temp and no data to show how much certain species react to temp change. So basically you can say moisture is known to have a huge effect on the result.

Mann in particular ignores all of the rules for dendro sites and piles them all together. (even with the knowledge that some trees he uses are collected specifically for moisture records). Mann’s mode of operation over several papers is to use any old proxy and let the BS math sort it out.

I’m not botanist, but I am an enthusiastic gardener. Unfortunately for me, I live in north Texas. Between the wind, the cold, the sometimes dry climate, and the blistering Texas summer sun, it’s not the greatest place to grow a showplace garden.

I live west of Dallas, in an area that is dry 4 years out of 5, bone dry two of those four years, and rainy as all get out one year out of five. It’s brutally hot 5 summers out of 5, it’s just that two of them are a withering heat, two are a dry heat, and one is a mosquito-infested sauna. I have noticed over the past 12 years that my little tree collection doesn’t grow at all (and in fact, goes sort of dormant) in the withering years, grows a little in the dry years, and grows like crazy in the sauna year. I should add that I don’t water my trees after the first six months, because if something around here doesn’t grow really deep roots (which they will do if they have to look for water), it will blow away.

Here is my post which led to the CA post.
http://noconsensus.wordpress.com/2008/12/01/the-800lb-gorrilla-in-the-hockey-sticks-locker-room/

“They are simply not a robust measure of global warming – long term trends are much more relevant.”

Without specifying what would be considered a ‘long term trend’. Apparently it’s more than 10 years. When GISS states we’ll see record temperatures hit on a 2-3 years basis (visit their website for confirmation of this), or the MET Office predicts specific years:

http://www.metoffice.gov.uk/corporate/pressoffice/2007/pr20070104.html

It seems to be OK. But when things don’t pan out, the ‘opposition’ is being unreasonable by pointing to nearly 10 years of contradicting data because it’s too ’short’ and such individuals are apparently fooling themselves.

Each side should be held to the same standards of criticism. It’s a strange kind of one sided argumentation that always sounds reasonable if you don’t stop to think about what is actually being said.

The so called peer review of the first Mann opus failed to spot that his conclusion contradicted the known historical record from the Vikings in Greenland, to the paintings of Brughel, cathedral building, River Thames freezing (not done that since 1821 just before the Victorians started driving round in their 4×4s) and the flat thermometer record from the Armagh observatory. All this could be dealt with if the amply funded Mann team could go and update the tree record of the past 30 years which would confirm that his findings are peer reviewed (by his mates) nonsense.

Cheers

Paul

To argue that the study is “robust” is to really argue from an ideological position. It’s one of the worst studies ever done.

Everyone should read the links posted but in summary:

If a particular series happens to respond in the opposite way to what Mann wanted, i.e., shows recent cooling instead of warming, Mann flips the proxy upside down in order to still get the result he wants. He also uses proxies that have been stated by the providers of the proxies to be corrupted for recent decades. When a very small number of these types of proxies are removed, a completely different result is produced. There is nothing “robust” about a result like that.

This is a bad study done by a lousy scientist. Cranks are everywhere but a real scientist who does work like this hurts the reputation of science itself.

AGW believers who try to defend appallingly bad work, show that they are interested in defending a conclusion rather than looking at the science in an honest way. One bad study doesn’t prove or disprove AGW so let’s just admit it’s bad and move on to looking at other issues. There is more to AGW than just one (exceptionally) bad study.