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Global Temperature Change, baseline in History

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Dancing David said:
1. Are there ways that dendrochronology can be used usefully to add to climate pictures , if the temperature may not be accuarte through this methd. In what cases might it be accurate or how could it be used?
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Something to keep in mind is that many things effect the size of tree rings, that doesn’t mean useful data isn’t there, it just means you need to filter out the noise first.

It’s not peer reviewed but here is a comprehensive overview by a professional statistician of the technique used by Mann et al.

http://tamino.wordpress.com/2008/02/16/pca-part-1/
http://tamino.wordpress.com/2008/02/20/pca-part-2/
http://tamino.wordpress.com/2008/02/21/practical-pca/
http://tamino.wordpress.com/2008/03/06/pca-part-4-non-centered-hockey-sticks/
http://tamino.wordpress.com/2008/03/19/pca-part-5-non-centered-pca-and-multiple-regressions/

The reason tree rings are such a sore spot with some people is because it’s part of their justification for claiming Mann’s 1998 paper “was wrong”. It’s somewhat buried in the technique, the only reason tree ring data made it into Mann’s paper was because they were a very close match with the last 150 years of instrument measurements. If they had not matched they would have been discarded along with the other information that failed to match the instrument temperature record.
 
lomiller said:
Something to keep in mind is that many things effect the size of tree rings, that doesn’t mean useful data isn’t there, it just means you need to filter out the noise first.

It’s not peer reviewed but here is a comprehensive overview by a professional statistician of the technique used by Mann et al.

http://tamino.wordpress.com/2008/02/16/pca-part-1/
http://tamino.wordpress.com/2008/02/20/pca-part-2/
http://tamino.wordpress.com/2008/02/21/practical-pca/
http://tamino.wordpress.com/2008/03/06/pca-part-4-non-centered-hockey-sticks/
http://tamino.wordpress.com/2008/03/19/pca-part-5-non-centered-pca-and-multiple-regressions/

The reason tree rings are such a sore spot with some people is because it’s part of their justification for claiming Mann’s 1998 paper “was wrong”. It’s somewhat buried in the technique, the only reason tree ring data made it into Mann’s paper was because they were a very close match with the last 150 years of instrument measurements. If they had not matched they would have been discarded along with the other information that failed to match the instrument temperature record.
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Thanks for that explanation, the evil genius just oozes out of Mann's work, and I can see why Climateaudit has pursued him so relentlessly over the past years, he is a witch and must be burned.

*snaps out of it*

Very interesting, and informative. It's good to get an intelligent assessment of what Mann and others have been trying to do and how they are doing it.
 
mhaze said:
This consists of a criticism in Nov 2007, then an blog interchange with Rabbit that runs through late Dec 2007. But they show no awareness of Loehle's "Correction" published in November.

Thus their comments I interpret as applying to the original paper.

Are there any valid points given the Correction?
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I assume the correction you refer to is his removal of all data post 1945, or has he made another correction as well?

The problem here is that the best reference to verify his proxy reconstruction worked as intended needed to be removed. So yes an issue with his method was eliminated, but a the same time we loose much of our ability to verify his results against known values.

And, again, as I mentioned the journal this paper appeared in was of very low quality. Low enough that work appearing there should be treated much more like a blog then a peer review journal.
 
From the third link from Tamino.

Anthony Watts wonders about the adjustment to Cedarville data. What’s revealing is the commentary; the first comment gives the tone of the entire thread:

GISS has got to get rid of those warmer 1930s. So, cool them down and raise pre 1930s, then the whole series starts to look flat once smoothed and combined, and the hockey stick reappears like magic.

​
The thread makes interesting reading for those who like conspiracy theories, but apparently neither Anthony Watts nor any of his readers even considers the possibility that there might be a good reason for the adjustment, namely, a clearly established spurious cooling trend in Cedarsville after 1930 and a spurious warming trend before 1930, both of which are confirmed by comparison to neighboring stations.
Watts (and his readers) are definitely under the impression that GISS adjustments are adding false warming to all kinds of stations willy-nilly, leading to a false global-warming trend. They fail, of course, to mention nearby Mt. Shasta, with a spurious warming trend post-1930 and spurious cooling trend pre-1930, which has been adjusted in a manner opposite to Cedarville. They fail to mention that the two adjustments mostly cancel each other out, the net effect being slightly more cooling this century than without adjustments. The fail even to consider that in the global record, there’s a Mt. Shasta for every Cedarville, in fact one might guess that there are far more stations with a cooling adjustment than with a warming one, because the hinged-line adjustment was designed to mimic UHI which is predominantly false warming.
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Sums it all up, from what I have read. There is a largely uninformed and ignorant commentary going on out there which is no better than third rate conspiracy theories based on a complete misunderstanding of what they are criticising. I'm all for scepticism, but what people like Watts dish up is ignorance. For some reason, he's treated like a hero, and someone like Stephen McIntyre, who claim to be a statistician, should be able to correct his errors.
 
lomiller said:
Something to keep in mind is that many things effect the size of tree rings, that doesn’t mean useful data isn’t there, it just means you need to filter out the noise first.

It’s not peer reviewed ...
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And so your blog links are soundly rejected. Surely those arguments, if anywhere near accurate, could find their way into a journal?

No? Hmmm...

a_unique_person said:
Here is some of the drivel they publish.

http://homepages.tesco.net/~kate-and-david/2007/Holland(2007).pdf
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Abstract excerpt. Doesn't sound drivelish.

It is concluded that the IPCC has neither the structure nor the necessary independence and supervision of its processes to be acceptable as the monopoly authority on climate science. Suggestions are made as to how the IPCC could improve its procedures towards producing reports and recommendations that are more scientifically sound.
 
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mhaze said:
And so it is rejected.
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Why? Are you having trouble following the math?

mhaze said:
And so your blog links are soundly rejected. Surely those arguments, if anywhere near accurate, could find their way into a journal?

No? Hmmm...
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Surely you realize that to make its way into a journal something needs to be groundbreaking, not a rehash of what’s already known.
 
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mhaze said:
And so your blog links are soundly rejected. Surely those arguments, if anywhere near accurate, could find their way into a journal?

No? Hmmm...



Abstract excerpt. Doesn't sound drivelish.

It is concluded that the IPCC has neither the structure nor the necessary independence and supervision of its processes to be acceptable as the monopoly authority on climate science. Suggestions are made as to how the IPCC could improve its procedures towards producing reports and recommendations that are more scientifically sound.
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Stop being a bunch of communists seems to be his suggestion.
 
a_unique_person said:
Originally Posted by mhaze
Abstract excerpt. Doesn't sound drivelish.

It is concluded that the IPCC has neither the structure nor the necessary independence and supervision of its processes to be acceptable as the monopoly authority on climate science. Suggestions are made as to how the IPCC could improve its procedures towards producing reports and recommendations that are more scientifically sound.​

Stop being a bunch of communists seems to be his suggestion.
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Funny, what I read as what he meant was...what he said...

It is concluded that the IPCC has neither the structure nor the necessary independence and supervision of its processes to be acceptable as the monopoly authority on climate science. Suggestions are made as to how the IPCC could improve its procedures towards producing reports and recommendations that are more scientifically sound.
 
mhaze said:
Hill and mountainside treelines have strong merits.

I'll find the list of of studies and links used in that chart.

Not just O18-the problem clearly extends to measuring "tree rings"
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True, but there are merits in their use nonetheless, as I said I am a pluralist, I despise the effect that montheism has had on some societies, there are no single causes, there are no single methods that are 'best'.

So while there may be some methodological issues in tree ring analysis, and an error factor, they are still useful. I am mainly familiar with them as drought indicators.
 
lomiller said:
Something to keep in mind is that many things effect the size of tree rings, that doesn’t mean useful data isn’t there, it just means you need to filter out the noise first.

It’s not peer reviewed but here is a comprehensive overview by a professional statistician of the technique used by Mann et al.

http://tamino.wordpress.com/2008/02/16/pca-part-1/
http://tamino.wordpress.com/2008/02/20/pca-part-2/
http://tamino.wordpress.com/2008/02/21/practical-pca/
http://tamino.wordpress.com/2008/03/06/pca-part-4-non-centered-hockey-sticks/
http://tamino.wordpress.com/2008/03/19/pca-part-5-non-centered-pca-and-multiple-regressions/

The reason tree rings are such a sore spot with some people is because it’s part of their justification for claiming Mann’s 1998 paper “was wrong”. It’s somewhat buried in the technique, the only reason tree ring data made it into Mann’s paper was because they were a very close match with the last 150 years of instrument measurements. If they had not matched they would have been discarded along with the other information that failed to match the instrument temperature record.
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Thanks, I am aware of the usefulness of dendrochronology and the political leanings of some people are rather obvious in the lack neutral language they use. Thanks.
 
Hello people, we have enetered an interesting discussion and I would like to thank everyone for their participation, however we are starting to get off the topic.

So tree rings have some error issues, Loehle raises good points that I am sure are well known in dendrochronology and perhaps should be considered (if they aren't already), however they are just one source of data and are not invalidated except potentialy for the O*18 measure.

Many sources exist for data, some are peer reveiwed and some are not.
 
Dancing David said:
True, but there are merits in their use nonetheless, as I said I am a pluralist, I despise the effect that montheism has had on some societies, there are no single causes, there are no single methods that are 'best'.

So while there may be some methodological issues in tree ring analysis, and an error factor, they are still useful. I am mainly familiar with them as drought indicators.
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Mhaze has derided the 'spaghetti' graph, which is just Mann and others trying to use several proxies to try to ensure they get a good spread of analysis, besides tree rings.
 
Dancing David said:
True, but there are merits in their use nonetheless, as I said I am a pluralist, I despise the effect that montheism has had on some societies, there are no single causes, there are no single methods that are 'best'.

So while there may be some methodological issues in tree ring analysis, and an error factor, they are still useful. I am mainly familiar with them as drought indicators.
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Useful, but not to determine historical temperature. From the article in Nature:
These results suggest that most tree photosynthesis occurred when leaf temperatures were about 21 uC, irrespective of latitude and average growing-season temperatures. The d18O in a tree ring inherently represents a whole-canopy integration of leaf-level processes that are weighted towards periods of maximal carbon assimilation. This effective homeostasis of leaf temperatures means that there was a significant elevation of leaf temperatures over mean growing-season temperatures in colder climates and, as a corollary, leaf temperatures that were lower than ambient temperatures in hotter, temperate climates (Fig. 2b). In the subtropical sites, tree-leaf temperatures were much closer to ambient temperatures. The relationship of leaf temperature to ambient temperature holds across closely related congeneric species as well as through the larger phylogenetic groupings of angiosperms and gymnosperms.​
Dancing David said:
So tree rings have some error issues, Loehle raises good points that I am sure are well known in dendrochronology and perhaps should be considered (if they aren't already), however they are just one source of data and are not invalidated except potentialy for the O*18 measure.
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O18 uptake occurs when ______ (fill in the blank)

Tree ring width does not correlate highly with O18?

This speculation seems impossible. Unless you can present evidence for such a claim, it's quite reasonable to conclude that these results invalidate tree ring proxies for temperature.
 
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a_unique_person said:
Thanks for that explanation, the evil genius just oozes out of Mann's work, and I can see why Climateaudit has pursued him so relentlessly over the past years, he is a witch and must be burned.

*snaps out of it*

Very interesting, and informative. It's good to get an intelligent assessment of what Mann and others have been trying to do and how they are doing it.
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I read those a few weeks ago. Very informative, as you say. Notice how the CA crowd pretty much ignore it until part 4, when they pile in.
 
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