Category Archives: Divergence

M&M at the NAS Panel

Back to reporting on our presentation to the NAS panel, after which I’ll report on Mann. We presented last in the day, immediately following von Storch. Hughes and Mann presented on Friday morning. We gave them a long written presentation, and touched the high points in our PPT, also providing them with a CD of […]

D'Arrigo: Making Cherry Pie

D’Arrigo presented their new study. I went over and introduced myself and said that I thought that their new study was much better than Osborn and Briffa and that it was too bad that they hadn’t received the same publicity. She said – Well, I guess that’s a compliment of sorts. I was trying to […]

A Briffa Collation

As I’ve mentioned before, you have to really watch the pea under the thimble whenever Briffa is presenting a series. I showed before how the post-1960 decline in MXD reconstructions was simply excised from the record and carried forward into the IPCC spaghetti graph where the overlay of colors made the detection virtually impossible to […]

Briffa: Large-Scale Decline in Ring Widths

I’ve talked recently about the phenomenon of cherry picking tree ring chronologies with upticks in the small-subset (10-20) compilations used in typical Hockey Team multiproxy studies (e.g. Jones et al 1998; Crowley and Lowery 2000, etc., most recently Osborn and Briffa, 2006; and to a slight lesser extent D’Arrigo et al, 2006 (where there was […]

Positive and Negative Responders

Just when you think that you’ve heard of all the possible problems with tree rings, the newest issue comes from “positive” and “negative” responders to temperature within the same site. These issues are discussed in a number of articles by various post-docs associated with Jacoby and D’Arrigo with the latter as co-authors. So in fairness […]

Upside-Down Quadratic Proxy Response

David Stockwell has suggested a discussion of nonlinear responses of tree growth to temperature. I’ve summarized here some observations which I’ve seen about bristlecones, limber pine, cedars and spruce – all showing an upside-down U-shaped response to temperature. The implications of this type of relationship for the multiproxy project of attempting to reconstruct past temperatures […]

"Modern Sample Bias", RCS and Briffa’s "Adjustment"

Briffa’s Ph.D. student, Thomas Melvin, discusses the important impact of “modern sample bias” on RCS chronologies, discussing Tornetrask and Finnish sites in detail.

Post-1980 Proxies #4: Wilmking et al. [2004]

Wilmking et al. carried out a comprehensive sampling of 1558 white spruce trees at 13 treeline sites in the Brooks Range and Alaska Range. The date of the sampling is not stated but seems to be between 2000 and 2003 and includes the warm 1990s. These findings cover the same species as were primarily used […]

Post-1980 Proxies #2: Alaskan Tree Rings

D’Arrigo et al. [GRL 2004] reports on tree rings taken from the Seward Peninsula in northwestern Alaska from white spruce from 14 sites near elevational treeline in summer 2002. We show here their figures, demonstrating that the "proxy" show no evidence of the warm 1990s and hot 1998, raising questions about the ability of this […]

Post-1980 Proxies #1: Twisted Tree Heartrot Hill

I get a lot of questions about post-1980 proxies and I find it a very interesting question. One would expect that 1998 – the "warmest" year of the millennium – and the 1990s – the "warmest decade" of the millennium would leave a loud signal in a valid proxy. I’m going to start discussing some […]