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 anomalously again in Crowley and Lowery (2000) [incorrectly citing the Briffa version]. The site is used in Esper et al [2002], whose data is unavailable and the version is not stated.The Briffa reconstruction is shown in Figure 1 below. Briffa et al. [1995] stated that 1032 was the "coldest year" of the millennium (over 6 deg C below normal) – the 1032 downspike is noticeable in the graph. The Briffa reconstruction also shows cold not simply in 1032, but through the 11th and 12th centuries, during the famous period of Viking exploration. Briffa et al. argued that these results showed that the Viking warmth was regional at best and to disparage the idea of a MWP. These conclusions were dramatic, especially at the time. Continue reading →
In most "long" presentations of climate change in the IPCC framework, we see Vostok ice core going back to about 800 Kyr, covering most of the Pleistocene. What easily gets lost sight of in this format is just how unusual the Pleistocene itself is. It is one of only a few glaciations in the entire history of the earth. There have been some interesting recent discoveries in the Pliocene – the geological period just before the Pleistocene. Here is some information on an interesting Pliocene wood sample collected in 1997 from north Greenland (c. 80°31.9″ⱎ, 65°25″ⱗ, 70 m). Continue reading →
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. Continue reading →
Here’s a beautiful picture of a foxtail pine from the MWP, illustrating eloquently the change in treelines: 
Original Caption: A dead trunk above current treeline from a foxtail pine that lived about 1000 years ago near Bighorn Plateau in Sequoia National Park. Continue reading →
In my post on Tornetrask showing the impact of the Briffa-Jones "adjustment", I didn’t comment on confidence intervals. Continue reading →
The inquiry about the impact of alpha trees reminded me of a cute little diagram truncation by Briffa, Jones et al. Continue reading →
I have some odds and ends in inventory about bristlecone and foxtail sites, which I’m going to post up, mostly because I find the information rather interesting. Most dendrochronologists assume that the bristlecone/foxtail sites are far too remote to have experienced direct human effects. As far as I’m concerned, this is an assumption that needs to be proven. There was widespread mining activity in the American Southwest in the 19th century, evidenced now by ghost towns. The mines were nearly all underground mines, all of which use timber for roof support. This happens to be something that I know about. I’ll show examples in a couple of Colorado locations. My hunch is that many of the roads used by Graybill to reach the bristlecone sites were originally developed to access small 19th century mines. I’ll show some examples of this – there are some striking examples. There’s no special reason for starting with Cirque Peak. I’m not making big claims about this material, other than I find it interesting. Continue reading →
Here is a type of diagram which I often do on tree ring data. I’ve never seen anything like this in the tree ring literature, but some of you may be interested. Continue reading →
The Polar Urals tree ring site is another staple of multiproxy studies, being used in Bradley and Jones [1993], Hughes and Diaz[1994], Overpeck et al. [1997], Jones et al. [1998], MBH98, MBH99, Crowley and Lowery [2000], Esper et al. [2002], Bradley, Hughes and Diaz [2003] and Rutherford et al. [2005] (which recycles MBH98). In fact, it seems to have been used in every study. Continue reading →
Sometimes the Mann Hockey Stick (1999) is eclipsed by another reconstruction which goes twice as far back and with even less statistical significance (if that’s possible) than the original.
Yes, it’s the "Mann Hockey Stick mark deux" produced by Drs Jones and Mann to widespread indifference in 2003. Steve has tried replicating this one as well, but guess what? Mann won’t give all the necessary statistical steps (including the weightings used) in order to replicate the graph. Quel surprise….
Continue reading →
Climate Audit 