Category Archives: Divergence

Briffa et al 2001 – More on Divergence

After several years of trying, Briffa and Osborn have finally listed the sites used in Briffa et al 2001 and related publications. Briffa had reported results on large networks of over 300 sites collected by Schweingruber. Schweingruber had archived over 400 sites at WDCP. However, it was impossible to tell exactly which sites had been […]

Late 20th Century Limber Pine Growth Decline

Constance Millar, url who wrote an excellent article on the medieval warm period in California, discussed here has written an interesting and timely article (presently in review) on thelate 20th century in the Sierra Nevadas, entitled: Response of high-elevation limber pine (Pinus flexilis) to multi-year droughts and 20th-century warming; Sierra Nevada, California.

Juckes and the Divergence Problem

Juckes discusses the Divergence Problem as follows: Particular concerns have been raised about … the high latitude Eurasian trees (which have and anomalously low growth anomaly in the late 20th century — Tornetraesk, Fennoscandia, Yamal, Northern Urals in Table 1) No one has ever said that Yamal has an anomalously low growth anomaly in the […]

Survivorship Bias

bender has sent in the following interesting graphic showing how drought-caused dieback could bias a tree ring chronology and interfere with interpretation of past records, emphasizing the continued need to keep U-shaped temperature response functions firmly in one’s mind when considering these series. [image being re-sized] (2012 note) For reference, here are some related postings […]

NAS Panel Report

The early rumors on the NAS Panel was that it was “two handed” -on the one hand,…, on the other hand, … with something for everyone. I’d characterize it more as schizophrenic. It’s got two completely distinct personalities. On the one hand, they pretty much concede that every criticism of MBH is correct. They disown […]

NAS Panel – What I'll Be Looking For

The NAS Panel is scheduled to issue its report, "Surface Temperature Reconstructions for the Last 2,000 Years" at 11 a.m. on Thursday. I suspect that many people would expect me to be worried about what the panel will say. Actually, I’m not worried in the slightest. Based on presentations to the panel, NAS is in […]

Rutherford 2005 and the Divergence Problem

Rutherford et al 2005 (the et al being half the Hockey Team: Mann, Bradley, Hughes, Briffa, Jones, Osborn) is a re-statement of the MBH98 network (flawed PCs and all) and the Briffa et al 2001 network using RegEM. I haven’t figured out exactly what the properties of the RegEM method are as compared to other […]

"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 […]

Mann at the NAS Panel

This post got deleted in the server crash. I typically post up from written text, but usually do a final edit as I input onto the blog, so the present note will probably differ a little from what I posted up yesterday, but probably not materially. Mann did not present anything germane that had not […]

Cook et al[2004]: More Cargo Cult?

Reader Bart S. has argued that Cook et al [QSR 2004] disposed of the "Divergence Problem", the name applied at the NAS panel on March 2-3, 2006 for the problem that, if the proxies do not record late 20th century warming, how can we be sure that they recorded potential earlier warming in the MWP. […]