Comments on: Juckes and the Mitrie Project

By: Willis on “Getting authors to respond to questions” « Climate Audit

Sat, 04 Dec 2010 18:13:46 +0000

[...] (Juckes and the MITRIE Project) [...]

By: Hans Erren

Hans Erren — Fri, 02 Feb 2007 11:23:21 +0000

http://mitrie.badc.rl.ac.uk/

Introduction
MITRIE is funded by the Netherlands Environment Assessment Agency (RIVM) as part of the Netherlands `Scientific Assessment and Policy Analysis’ (WAB) programme. More information about this programme can be found here (in Dutch). http://www.klimaatportaal.nl/index.htm

There has been considerable interest in paleoclimate reconstructions of temperature over the last millennium. A wide variety of techniques have been used, with sometimes obscure details. The interrelation among the techniques is unclear. This project will seek to achieve two distinct but related aims: firstly, to aid public understanding by providing a web site explaining the scientific basis and providing data and software; secondly, to contribute to the scientific debate by reviewing recent work and attempting to isolate the key differences between the different methodologies within a common framework.

Proxy climate reconstructions draw on a wide variety of data sources. Reviews of some of the data sources can be found here. http://mitrie.badc.rl.ac.uk/short_reviews

NEW:: Our work is now published in a Climate of the Past Discussion paper. Software used for this paper can be downloaded here, the data used is provide in the supplementary material.
http://www.copernicus.org/EGU/cp/cpd/2/1001/cpd-2-1001.htm
http://home.badc.rl.ac.uk/mjuckes/mitrie_files/software/mitrie_python.tar

A comment on an error in McIntyre and McKitrick (2005) [Energy and Environment] here.
http://home.badc.rl.ac.uk/mjuckes/mitrie_files/pdfs/comment_ee_figure2.pdf

A comment on the disclosure of software and data can be found here.
http://mitrie.badc.rl.ac.uk/disclosure_1

By: Steve McIntyre

Steve McIntyre — Mon, 06 Nov 2006 11:18:41 +0000

#18. The extend.persist function was used in our study only to extend proxies to 1980 by persistence, emulating a procedure used in Mann et al. It’s not a technique that we endorse. (We noted that a surprising number of MBH98 proxies were so extended in MM03, but did not concern ourselves with this particular issue in our MM05 papers, contrary to one of Juckes’ claims.) Contrary to Martin’s statement here, extension by persistence is used over and over again in Juckes et al. Indeed, Juckes spends a considerable amount of energy arguing that these extensions don’t have any material impact on final reconstructions – an issue that was not in play in any ofd the 2005 papers.

In our own smoothing by (2M+1) gaussian filters, we padded by the mean of the closing M values, as is easily observed by archived code. On no occasion did we pad a smooth by padding with M endpoint values.

Juckes did not explain how he dealt with end point padding in his article. It is my surmise that he applied this technique in his article. But perhaps he did something else and, as Willis requested, can explain what he did.

By: Willis Eschenbach

Willis Eschenbach — Mon, 06 Nov 2006 10:47:20 +0000

Martin, thanks for the reply. What technique was used regarding the smoothing at the endpoints of your study?

By: Martin Juckes

Martin Juckes — Mon, 06 Nov 2006 10:45:44 +0000

re #11 and following: this is taken from code which was trying to reconcile differences between our calculations and Stephens. It does exactly the same as the extend.persist function used by Stephen. This technique is not used in our published study. Following earlier criticism (I thought by Stephen, but perhaps it was someone else, given that he obvbiously used the technique himself in his Energy Environment, 2005 paper) I saw no reason to use it. It is, however, used by McIntyre and McKitrick (2005), so I needed to put it in there to examine the differences between our paper and theirs.

By: Willis Eschenbach

Willis Eschenbach — Mon, 06 Nov 2006 05:19:04 +0000

#16. Ooooh, what does the tricksy Hobbit have in its pockets? Pads it first, then wraps it … nasssty. Makes it look like you haven’t pinned it, when in essence you have. In fact, since it’s padded with “y” repetitions, and the length of the filter is 2*y+1, it never wraps at all.

This is a very poor choice for endpoints. It is not justified by any mathematical or practical advantage, all it does is tend to pull the average towards the final point. It is equivalent to assuming that the recent trend will continue, which is correct … but only about half the time …

By: Steve McIntyre

Steve McIntyre — Mon, 06 Nov 2006 03:05:50 +0000

#15. NOte that Juckes first pads the series with 10 repetitions of the closing value. So the end point is very heavily weighted and it’s a near-pin.

By: Willis Eschenbach

Willis Eschenbach — Sun, 05 Nov 2006 22:13:08 +0000

I haven’t examined the logic under the function, but the function is clear. “circular = TRUE” defines how it handles the endpoints, and that it handles them by padding the end of the data by mirroring (around x but not y) at the ends of the function. If so, that’s not the best method possible … but on the other hand, it doesn’t pin the endpoints.

By: Russ Steele

Russ Steele — Sun, 05 Nov 2006 19:56:49 +0000

And, governments are making climate change policy on 28 years of unevaluated scripts. Where is all this blind science going to lead us? With out CA doing the heavy lifting, we would be blindly following Al Gore off an economic cliff. Thanks Steve for all you do!

By: Steve McIntyre

Steve McIntyre — Sun, 05 Nov 2006 17:21:49 +0000

#12. Examination of script is NEVER done in climate peer review. I acted as a peer reviewer for Climatic Change and asked to see script; the editor, Stephen Schneider, said that no one had ever made a similar request in 28 years of editing and refused to even ask the author to provide script.