Just got back from Washington a few minutes ago (I think that the presentations went very well) and saw this press release from Wahl and Amman (link). The points appear to be ones that have been posted up at realclimate before, which we’ve fully considered and, in my opinion, don’t lay a glove on our […]
Post-1960 values of the Briffa MXD series are deleted from the IPCC TAR multiproxy spaghetti graph. These values trend downward in the original citation (Briffa [2000], see Figure 5), where post-1960 values are shown. The effect of deleting the post-1960 values of the Briffa MXD series is to make the reconstructions more “similar”. The truncation […]
Here is an interesting splice of Moberg and satellite data. Blue is Moberg, grey is Moberg error bars, red is instrumental, all downloaded from the Nature SI; purple is satellite. At right is the post-1850 blow-up. You can see that the post-1980 satellite temperatures are high but not off the charts relative to Moberg’s reconstruction.
Briffa’s Tornetrask temperature reconstruction is done by regression analysis. Previously I reported that Briffa purported to justify his upward adjustment of 20th century MXD chronology (and downward adjustment of MWP reconstruction) by a very slight improvement of R2 (going from 0.503 to 0.553 – see Clim. Dyn 1992). I’ve attempted to replicate these regression calculations […]
There appear to be some important sampling differences between subfossil and modern (living) cores. Briffa et al [CD 1992, 114] provide the following caveat with respect to using the RCS method (global curve fitting) for Tornetrask: “In applying this [RCS] method, each individual tree ring series should ideally start with the innermost ring (preferably near […]
The three cores which account for 1032 being the "coldest" year of the millennium are 862450, 862470 and 862030. One other core (862460) is dated to the late 10th and early 11th century and contributes to early 11th century "coldness". The placement of these 4 cores has to be interpreted from the ring width information […]
The tree ring dataset for the critical Polar Urals site has gaps of up to 59 years, has cores with as many 7 breaks in them. The problems are so pervasive that COFECHA testing simply fails – an almost unprecented occurrence in a tree ring data set.
The Polar Urals site is a staple of multi-proxy studies. The Briffa et al. [1995] version is used in Jones et al [1998], MBH98, MBH99, Briffa et al. [2001] and most recently Jones and Mann (2004). An earlier version by Graybill and Shiyatov was used in Bradley and Jones [1993], Hughes and Diaz [1994] and […]
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.
In my post on Tornetrask showing the impact of the Briffa-Jones "adjustment", I didn’t comment on confidence intervals.
Climate Audit 