From	Phil Jones	Date	Fri Jul 29 16:30:35 2005
To	Tim Osborn, Tett, Simon
CC	Keith Briffa
Subject	Re: Bristlecones!
Simon, If you go to this web page [1]http://www.ucar.edu/news/releases/2005/ammann.shtml You can click on a re-evaluation of MBH, which leads to a paper submitted to Climatic Change. This shows that MBH can be reproduced. The R-code to do this can be accessed and eventually the data - once the paper has been accepted. IPCC will likely conclude that all MM arguments are wrong and have been answered in papers that have either come out or will soon. MBH is just one curve of many - more now than there were in 2001. MBH is still in the spaghetti of curves, and is not an outlier. If there are outliers it will be Esper et al. and another one. Bristlecones are only crucial to the issue if you are MM. They misused them, by their PCA application. This is all well-known to those in the know. I have reviewed the CC paper by Wahl and Ammann. It reproduces all the mistakes MM have made, so they know how and why their results have been achieved. I can send you the paper if you want, subject to the usual rules. MBH have all responded to the same requests as IPCC got from the US Senate. Their responses are all posted at [2]http://www.realclimate.org/ The skeptics have shot themselves in the foot over this one. Cheers Phil At 15:17 29/07/2005, Tim Osborn wrote: At 14:27 28/07/2005, Tett, Simon wrote: John Houghton is being quized by bits of the US senate. One question is "Whats the status of the review of the Mann hockey stick temperature curve? I understand that studies by Stephen McIntyre and Ross McKitrick suggest that it relied on the statistically insignificant bristlecone pine. Is the IPCC taking another look at that work, which forms the basis for much of todays climate change debate?" My current thoughts on an answer is to say that other reconstructions show a similar pattern (though not magnitude). However how many of the other reconstructions use the bristlecone data? [I suspect yours does not] Hi Simon - I was away yesterday, so couldn't answer then. Hopefully it isn't too late to answer today. (1) I don't understand what they mean by describing the bristlecone pine as "statistically insignificant". (2) The Mann, Bradley and Hughes (MBH1999) reconstruction is only one small piece of information in today's climate change debate. (3) As far as I understand, then yes the MBH1999 reconstruction does give quite a lot of weight to a few western US tree-ring series, which are mostly bristlecone pines for the longest records. (4) Other reconstructions show similar shape (though not magnitude) and support similar conclusions (regarding the unprecedented nature of recent warmth/warming trend). This is the main argument to make, as you thought. Some of these other reconstructions do not include these bristlecones (e.g. Briffa, 2000; Crowley et al., 2003; Moberg et al., 2005; Briffa et al., 2001). Crowely and Moberg use different Bristlecone records I think. Other reconstructions do use the same Bristlecone pines (e.g., Mann and Jones, 2004). BUT the critical thing is that the studies either do not use these Bristlecone pines, or if they do use them, then they give them much more similar weighting to the other records used. I think MBH1999 is the only one that might give them a dominant weighting. (5) IPCC is assessing all published work that relates to these issues in preparation for the AR4 in 2007. This includes the McIntyre and McKitrick papers as well as papers that report results contrary to McIntyre/McKitrick, such as the paper in press by Wahl and Amman that shows the Mann et al. results are reproducible. cc'd for additional comments to Phil and Keith (when he's back). Cheers Tim Dr Timothy J Osborn Climatic Research Unit School of Environmental Sciences, University of East Anglia Norwich NR4 7TJ, UK e-mail: t.osborn@uea.ac.uk phone: +44 1603 592089 fax: +44 1603 507784 web: [3]http://www.cru.uea.ac.uk/~timo/ sunclock: [4]http://www.cru.uea.ac.uk/~timo/sunclock.htm Prof. Phil Jones Climatic Research Unit Telephone +44 (0) 1603 592090 School of Environmental Sciences Fax +44 (0) 1603 507784 University of East Anglia Norwich Email p.jones@uea.ac.uk NR4 7TJ UK ---------------------------------------------------------------------------- References 1. http://www.ucar.edu/news/releases/2005/ammann.shtml 2. http://www.realclimate.org/ 3. http://www.cru.uea.ac.uk/~timo/ 4. http://www.cru.uea.ac.uk/~timo/sunclock.htm