Category Archives: MBH98

Articles relating to the Mann, Bradley and Hughes 1998 reconstruction of past climate

Rule N and Weighted Regression

Today’s post, which has a forbidding title, contains an interesting mathematical and statistical point which illuminates the controversy over how many PCs to retain. In my re-visiting the totally unknown corner of Mannian methodology – regression weights and their determination – I re-parsed the source code, finding something new and unexpected in Mannian methodology and […]

A Challenge to Tamino: MBH PC Retention Rules

Today I wish to re-visit an issue discussed in one of the very first CA posts: did MBH98 actually use the PC retention rules first published in 2004 at realclimate here and described both there and by Tamino as “standard” selection rules. Much of the rhetorical umbrage in Tamino’s post is derived from our alleged […]

The Gift That Keeps on Giving Continued

Here is a little present for Jean S and UC. Something new from the gift that keeps on giving. Something that even I never noticed before. What we’re going to see is that in Mann-world, U.S. tree ring series are capable not merely of reconstructing world temperature, but 9 different “climate fields”. In effect, using […]

Tamino and the PC4

As noted previously, Tamino did not quote, cite or discuss how our articles reported key issues in his post – an omission that results in our research not being accurately represented in the record at Tamino’s site. I’ll discuss a couple of examples. It’s unfortunate that time has to be spent on such matters prior […]

"Mannian" PCA Revisited #1

One of Hansen’s pit bulls, Tamino, has re-visited Mannian principal components. Tamino is a bright person, whose remarks are all too often marred by the pit bull persona that he has unfortunately chosen to adopt. His choice of topic is a curious one, as he ends up re-opening a few old scabs, none of which […]

More Mystery at Sheep Mountain

The Sheep Mountain CA bristlecone site is the most important proxy in MBH and the MBH98 reconstruction actually doesn’t differ very much from the Sheep Mountain tree ring chronology (other than it ends in 1980 at pretty much the peak of the Sheep Mt chronology and doesn’t include the downtick in the 1980s.) Various efforts […]

Another Assignment for the EAS8001 Mission Impossible Team

Mission Impossible Team, here’s your assignment today. Unfortunately you failed your last assignment: replicating Mann’s claimed correlations. But that probably was impossible. Today your assignment is probably possible, but is a dangerous expedition into the dark underground – into the terrifying world of Mannian RegEM. Courage and perseverance will be required. You may not return […]

Schakowsky: "a different source which our staff had confirmed with Al Gore"

Here is an interesting exchange at the House Energy and Commerce Subcommittee hearings about the provenance of the hockey stick diagram in An Inconvenient Truth. Thanks to the reader who spotted this. Rep Stearns took aim at the apparent use of Mann’s Hockey Stick in Inconvenient Truth (the methodology of which had been severely criticized […]

The Sheep Mountain Update

This post contains an important calculation, which will affect the many multiproxy studies in which Graybill bristlecone chronologies impact results either directly or via Mann’s PC1. Hans Erren has digitized the data from the Ababneh Thesis. In Figure 1 below, I’ve shown the difference between the updated Sheep Mountain chronology and the Graybill chronology. The […]

Mann's co2detrend.f Calculation

If someone felt that it was necessary to detrend the bristlecone pine-based PC1 of Mann’s AD1000 network for CO2 fertilization, it’s doubtful that the initial instinct would be to coerce the data to a network of northern Canadian-Alaskan tree ring chronologies where the possibility of regional differences must surely be allowed for. Inspection of Mann’s […]