Comments on: Yamal and the Divergence Problem http://climateaudit.org/2009/10/07/yamal-and-the-divergence-problem/ by Steve McIntyre Thu, 20 Jun 2013 06:24:11 +0000 hourly 1 http://wordpress.com/ By: Skiphil http://climateaudit.org/2009/10/07/yamal-and-the-divergence-problem/#comment-404910 Fri, 15 Mar 2013 22:00:37 +0000 http://www.climateaudit.org/?p=7320#comment-404910 Note: the top of he blockquote (above “2881.txt”) is not from the email but rather from E.M Smith aka “Chiefio” on the web:

https://chiefio.wordpress.com/2012/01/06/foia-select-uv-and-tree-rings/

]]> By: Skiphil http://climateaudit.org/2009/10/07/yamal-and-the-divergence-problem/#comment-404909 Fri, 15 Mar 2013 21:56:28 +0000 http://www.climateaudit.org/?p=7320#comment-404909 Fascinating to now see the following email (Melvin to Briffa) about “divergence” issues which was also written in Oct. 2009:
(H/t Chiefio and Tom Nelson)

Of UV and Tree Rings

[ This one is interesting as it gives a nice laundry list of things they know are wrong with the present method of using tree rings. UV is included on the list. So much for that whole "settled science" meme... -E.M.Smith ]

2881.txt

date: Wed Oct 14 13:51:06 2009
from: Tom Melvin
subject: Finland Conference
to: Keith

Keith,

By June we are unlikely to have the long Eurasian paper ready to discuss.
Would it be better for you to present on Divergence e.g.

CHALLENGES POSED BY DIVERGENCE

1. Problem with curve-fitting e.g. Hugershoff (Briffa 1998) and trend distortion – part solution Signal free.

2. Problem with mixing sloping and horizontal curve fitting in Arstan (e.g. D’Arrigo 2004) – part solution RCS.

3. End effect problems with RCS (Briffa – Hughes book) – e.g. sample bias

4. Problem with updating chronologies (TTHH and Grudd 2008, Tornetrask)

5. Potential problem with Crown dieback (e.g. responders / non responders)

6. Potential MXD in sapwood problem ????

7. Potential competition problem – tree density changes RCS shape (Helama 2006)

8. Problem with non-linear response / skewed index distribution (Barber, Wilmking etc)

9. Remove all these and residual is real divergence – problem with identifying cause:
CO2 change / Nitrogen fertilisation / Global dimming / UV light / Drought stress/

Conclusion – Lots of work to do to clarify situation.

I would present on PBS//GUESS work.

We need to prepare abstracts in next week or so.

]]> By: A G Lamb http://climateaudit.org/2009/10/07/yamal-and-the-divergence-problem/#comment-197820 Mon, 19 Oct 2009 12:48:27 +0000 http://www.climateaudit.org/?p=7320#comment-197820 BBC Link: http://news.bbc.co.uk/earth/hi/earth_news/newsid_8311000/8311373.stm

]]> By: A G Lamb http://climateaudit.org/2009/10/07/yamal-and-the-divergence-problem/#comment-197819 Mon, 19 Oct 2009 12:38:44 +0000 http://www.climateaudit.org/?p=7320#comment-197819 Re: A G Lamb (#240),

]]> By: Hu McCulloch http://climateaudit.org/2009/10/07/yamal-and-the-divergence-problem/#comment-197818 Sun, 18 Oct 2009 11:36:23 +0000 http://www.climateaudit.org/?p=7320#comment-197818 RE Hans Erren #238,

just curious, has there ever been an attempt to correct tree rings for co2 fertilisation?

I did this in Comment #32 of my 4/7/08 post, “More on Li, Nychka and Ammann”. See also #46 of that thread.

Briefly, I found that including CO2 greatly weakened the significance of the 4 TR series included in the 14 MBH99 series LNA considered, and in some cases eliminated it altogether. The latter included “Urals”, evidently before the “Yamal Substitution” under discussion had taken place. PC1, on the other hand, remained significant, albeit greatly weakened.

In Comment #46, I show that using Mizon’s more stringent approach to serial correlation, even PC1 is not robust to inclusion of CO2.

CO2 is getting rather OT here — perhaps this could be continued on the old LNA thread?

]]> By: Hans Erren http://climateaudit.org/2009/10/07/yamal-and-the-divergence-problem/#comment-197817 Sat, 17 Oct 2009 23:58:02 +0000 http://www.climateaudit.org/?p=7320#comment-197817 just curious, has there ever been an attempt to correct tree rings for co2 fertilisation?

]]> By: Mark http://climateaudit.org/2009/10/07/yamal-and-the-divergence-problem/#comment-197816 Wed, 14 Oct 2009 20:08:03 +0000 http://www.climateaudit.org/?p=7320#comment-197816 RE Hu #234,

Yes, I had gathered that just from my brief look into the matter. Thanks for making the point clearer than I did.

]]> By: Jeff Id http://climateaudit.org/2009/10/07/yamal-and-the-divergence-problem/#comment-197815 Wed, 14 Oct 2009 17:49:58 +0000 http://www.climateaudit.org/?p=7320#comment-197815 Re: Hu McCulloch (#234), It’s pretty bad when Hu starts snipping his thoughts :D

]]> By: bender http://climateaudit.org/2009/10/07/yamal-and-the-divergence-problem/#comment-197814 Wed, 14 Oct 2009 17:40:15 +0000 http://www.climateaudit.org/?p=7320#comment-197814 Re: Hu McCulloch (#234),
Exactly what NAS said. There is confidence back to AD1600. No sane person doubts this. Prior to about AD1400 the wheels come off the wagon.

]]> By: Hu McCulloch http://climateaudit.org/2009/10/07/yamal-and-the-divergence-problem/#comment-197813 Wed, 14 Oct 2009 17:32:26 +0000 http://www.climateaudit.org/?p=7320#comment-197813 RE Mark #233,
The Oerlemans graph, at http://www.sciencemag.org/cgi/reprint/1107046v1.pdf, only goes back to 1600 AD, and hence sheds no light on the MWP (c. 1000 AD), which is what the HS controversy is all about. We all know there was a LIA — the big issue is whether the 20th c was just emerging from the LIA and returning to normal, or if it was warmer than the pre-LIA norm.

This and most of the other HS graphs put up by RC were just red herrings. [self-snip]

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