One excellent feature of the Alaskan varvochronologists is that (unlike, say, Bradley and his coterie) some of them show and archive their work. The Kaufman student MSc theses are good at this. So too is Michael Loso’s work on Iceberg Lake. Thus while one can raise an eyebrow at (and criticize) their statistical peregrinations, at […]
The majority of Kaufman’s varvochronology proxies are various functions of varve thickness – which, if anything, seem more problematic than sediment BSi. While Kaufman’s offering memorandum to NSF promised consistency, the handling of varve thicknesses in the various selections seems to be anything but. Kaufman et al 2009 gives no hint of the varied functional […]
In fairness to Kaufman, he and his students actually did useful field work. Elsewhere I’ve noted that their MSc theses contain many helpful details on the Alaskan lakes. The situation is entirely different with the Greenland lakes, where Jonathan Overpeck was the point man for the ARCUS2k lake project collection. Kaufman et al 2009 contains […]
I observed yesterday that I had been unable to replicate the archived version of Kaufman’s Hallet Lake series – something that I thought was due to a change in the archived version (since the NCDC archive noted that a new version had been archived in Nov 2008.) This turns out not to be what happened. […]
At the second meeting of Kaufman’s PIs, one of the scientists plaintively asked: But shouldn’t we aim to do a synthesis that is only lake seds (at least as first step)? This logical building block was pushed aside (thereby allowing Briffa’s Yamal series to be recycled for the nth time) on the following grounds: some […]
Below is a plot comparing sediment BSi (biological silica) to depth (cm) from two of Kaufman’s lakes (done by different students). I’ve shown it by depth (rather than ascribed age) since the dating of these sediment series is not without some hairiness. I’ve shown equal lengths for each lake, both covering at least 800AD-present on […]
A common meme in Team-world these days is that any issues or errors are minor and that none of them “matter”. As we peel back the layers of Kaufman et al, this is the first line of Team defence. The rhetorical impact of Team reconstructions largely derives from the modern-medieval differential: is it in the […]
Darrell S. Kaufman, David P. Schneider, Nicholas P. McKay, Caspar M. Ammann, Raymond S. Bradley, Keith R. Briffa, Gifford H. Miller, Bette L. Otto-Bliesner, Jonthan T. Overpeck, and Bo M. Vinther (Science 9/4/2009) propose a reconstruction of Arctic summer land temperatures for the last 2000 years, using 23 diverse proxies. Decadal averages of each proxy […]
The backstory to the development of the Kaufman et al 2009 reconstruction is pretty interesting. A few years ago (after the MM criticisms of paleoclimate reconstructions), the US National Science Foundation sponsored the sampling of 30 Arctic lakes in a standardized way. It’s remarkable to compare the original population to the data sets used in […]
A CA reader sent me an email, noting the following entry in minutes of a meeting. M Loso inquired about Lonnie Thompson’s ice core data. These data are not presently available but will be investigated by Caspar. This comment is minuted in a meeting of PIs leading up to Kaufman et al 2009 – a […]
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