Tag Archives: Yamal

Is Yamal Homogeneous? An Esper-Style Answer.

Starting with the first of my recent posts on Yamal, I raised the issue of whether the CRU 12 actually came from a homogeneous population to the subfossil population. Although Briffa’s online response to my Yamal posts stated that CRU has “stressed” potential problems arising from “inhomogeneous” sources” in their “published work”, I have been […]

Taimyr and Yamal Location Maps

The following two Google maps show Taimyr and Yamal on consistent scales, together with Schweingruber sites in the area. The Taimyr chronology in Briffa 2000, as you may recall, not only didn’t have HS, but had a notable divergence problem. I’ve tried to accurately transcribe onto this location map the Naurzbaev 2002 sites (subfossil – […]

Core Count in Phil Trans B

The Yamal reconstruction was introduced in Briffa 2000, a survey paper that did not include elementary information like core counts. As a result, users of the Briffa 2000 Yamal reconstruction (including Mann and Jones 2003, Moberg 2005, Hegerl 2007; D’Arrigo 2006, IPCC 2007, etc…) used it without any knowledge that the core counts did not […]

Response to Briffa #2

As noted at CA last week, Briffa published a partial response to Yamal issues at the CRU website, one post discussing the impact of the Yamal chronology in various studies and another post discussing the Yamal chronology itself. For a response to Briffa’s online article on the impact of Yamal, I refer readers to last […]

Esper et al 2009 on West Siberia

Esper et al (Global Change Biology, in press) “Trends and uncertainties in Siberian indicators of 20th century warming” is relevant to our present consideration of Briffa’s Yamal, which I will get to shortly. The cutline in their abstract declares in effect that the divergence problem is not as “bad as we thought”: Despite these large […]

Briffa on Yamal Impact

Keith Briffa has a couple of posts today on Yamal – one discussing its impact in other multiproxy studies and the other on the Yamal chronology itself. His post on the Yamal chronology includes a careful consideration of various issues involved in the development of the Yamal chronology and is accompanied by an extensive archive […]

Re-Visiting the "Yamal Substitution"

Reader Tom P observed: If Steve really wants to invalidate the Yamal chronology, he would have to find another set of cores that also gave good correlation with the instrument record, but indicated a previous climate comparable or warmer than that seen today. As bender observed, Tom P’s question here is a bit of a […]

Core Counts and Reverse Engineering

Recently, after the posting of the Phil Trans B archive on Sept 8, 2009, I determined that the Yamal data set as used by Briffa is not more “highly replicated” than the Polar Urals data set and thus there is no basis for the preferential selection of the Yamal chronology over the Polar Urals chronology […]

Yamal and the Divergence Problem

One of the aspects of the Yamal discussion that is perhaps clearer to regular CA readers than to new readers is that Briffa’s Yamal chronology was very different from ring width chronologies previously reported in the area (including by Briffa itself.) Shortly after the publication of Osborn and Briffa 2006 and D’Arrigo et al 2006 […]

Yamal and IPCC AR4 Review Comments

I was one of the more industrious reviewers for IPCC AR4. In my Review Comments, I made frequent reference to Yamal versus the Polar Urals Update, expressing concern about the rationale for using Yamal rather than Polar Urals, an issue that is once again in play. Keith Briffa was the section author and can be […]

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