Category Archives: Esper et al 2002

"Mackenzie Mountains"

Last Friday, Science sent me measurement data used at 10 Esper sites — thanks to Science for this. Measurement data for 4 important sites (the Boreal and Upperwright foxtail sites; Polar Urals and Mongolia) were not sent. Hanson of Science commented that the Polar Urals site and some of the sites that he checked were […]

Esper on In-Site Cherry Picking

I noticed the following quote from Esper et al 2003 (reference in earlier post It is important to know that at least in distinct periods subsets of trees deviate from common trends recorded in a particular site. Such biased series represent a characteristic feature in the process of chronology building. Leaving these trees in the […]

Briffa vs Esper #2

People have been wondering why there is such difference between Polar Urals versions. In many cases, the archived Osborn and Briffa [2006] version (smoothed) is consistent with the emailed Esper et al [2002] version – but not always. It’s always worthwhile examining differences and here are a few.

Polar Urals Spaghetti Graph

I’ve got to get back to the NAS presentation and this will be my last post on Polar Urals and Yamal for a while, but it is all quite delicious. Anyway, here is a spaghetti graph of 3 Polar Urals results – including the results from Esper et al [2002] just disclosed by Science, all […]

Polar Urals: Briffa versus Esper

It’s interesting that the Hockey Team seems to be able to make spaghetti graphs of world temperature history when they can’t even arrive at a spaghetti graph for the Polar Urals. I posted up the difference between Briffa’s Yamal substitution and the updated Polar Urals ring widths. But before either one, there was Briffa’s Polar […]

Polar Urals “Grass Plot”

Here’s another look at Polar Urals using a “grass plot” showing cumulative ring width for individual trees against time. The trees plotted in black are from the original archive (russ021) and the ones plotted in red are form the 1998 update (russ176). This gives a little different viewpoint on variance stabilization issues. First, one of […]

Variance Stabilization in Esper Chronologies

Yesterday, Science sent me 13 Esper site chronologies, all standardized using RCS methods, one of which is the updated Polar Urals site. It’s hard to think of a better testing ground for Rob’s argument that the variance of the Polar Urals series disqualified it and mandated the substitution of the hugely hockey-stick shaped Yamal series. […]

A Reply from Science

A couple of days ago, I posted up a copy of a letter that I sent to Science on archiving or non-archiving in connection with Osborn and Briffa 2006, Esper et al [2002] and Thompson et al 1989 (Dunde); 1997 (Guliya). I received a reply from Science today, which they stated was not for “public […]

Letter to Science re Osborn and Briffa Data

The continued negligence of the major journals in ensuring that paleoclimate authors archive data in accordance with journal policies is very frustrating and, as previously noted, has reared its ugly head once again with Osborn and Briffa. I have had little luck in the past with Science (except for the Kilimanjaro sample dO18 data) but […]

Variability: Mann and Hughes [2002]

In response to the high-variability recosntruction of Esper et al. [2002] posted up here , Mann and Hughes [Science 296, 848 (2002)] replied: The basis used by Esper et al. for comparison with previous studies of NH temperature trends over the past millennium is flawed [imagine Mann calling someone else's work "flawed"] … Some of […]


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