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At this point about all that can be said is that the analysis of McIntyre and McKitrick, while perhaps a valid analysis, may not have been conducted on the proper data.

Of interest is the data on which the analysis and audit was done was provided by Mann's people! The complaint that Mann appears to be responding to as not being the proper data, is the XL spreadsheet form, though the raw data was also sent to M&M in text form as well, and copy returned to Mann for verification.

http://www.uoguelph.ca/~rmckitri/research/trc.html

"The proxy data set we received from Mann (pcproxy.txt). The text version is just as received from Mann (and re-sent back to him to verify)."

From what I can determine from M&M's paper they made a initial run with the XL data and noticed large discrepensies, compared the XL spreadsheet data apparently with the orginal text dataset.

http://www.multi-science.co.uk/mcintyre_02.pdf

"This led to a systematic comparison of MBH98 data to original data, identifying obsolete versions and undisclosed truncation of time series. Independent calculations of the proxy principal components convinced us that those in MBH98 were erroneous we updated and corrected the database and then applied MBH98 methodology, as publicly disclosed,"

Mann's response as stated in Quark Soup:

http://www.davidappell.com/

"However, Mann said today, a transcription error was inadvertently made in preparation of the spreadsheet, in which some multiple data that should have appeared in multiple columns was mistakenly overwritten into some single columns. A dataset that should have contained 159 columns of data in fact only contained 112 columns. So when M&M slid this dataset into their calculations, the results that came out were naturally in error."

Something not Kosher here, the "spreadsheet" was apparently rebuilt by M&M using original data, and the analysis run on that "original data" is what provided M&M's final output, not the "spreadsheet" sent to them by Mann's office.

Which makes just about everybody involved look a bit messy.

As I noted, there needs to be some splain'n done by somebody.

I agree that there should be an explanation; I wonder if Dr. Mann will do it directly to McIntyre and McKitrick, since he apparently doesn't think much of their effort to analyze his data. Publishing the "audit" paper in Energy and Environment may cause Mann to not bother to reply, as he might figure that would lend more credence to their results than he wants to give them. Had they published in a a more established science journal, particularly one focused on climate science, he would have been obligated (=forced) to respond.

It will be interesting to see if the media pressure and the pressure from the skeptical community on him will be sufficient to get him to respond. He is definitely capable of responding; after the Soon, Baliunas (et al.) papers came out early this year, due to persistent inquiries from the press, he collaborated on a response that was in the American Geophysical Union Eos publication.

Mann makes a lot of stuff available on his personal home page; here's the Eos article (PDF). The first figure shows a bunch of climate reconstructions over the past 1000 years.

On Past Temperatures and Anomalous 20th-Century Warmth

A couple of years ago there was some attention paid to an analysis published by Esper et al. (to which Mann responded). Esper's data, which appears in the figure noted above, shows much deeper cold periods than Mann's data (Mann's data was multi-proxy temperature records; Esper's was only tree-ring data). Esper's data is spikier, and there are a couple of times when his temperature record is significantly higher (0.2-0.3 C) than Mann's. But the overall pattern is still the same. If Esper's data and analysis are truly independent of what Mann et al. have done (same goes for the Crowley and Lowery analysis), then the likelihood that McIntyre and McKitrick operated on an erroneous data set increases. But it certainly appears that most of the blame for them receiving a flawed data set falls squarely on Dr. Mann.

If he'd been smart, he would have made certain that they got the correct data, and if their analysis had not shown any errors, then nothing would have happened. Now Mann is in a mess of his own making. It will be interesting to see the way in which he responds now.

After some work, I found a digital image version of the figure in the referenced article. Here it is, with caption. (Sorry it's so big.)

igure 1. Comparison of proxy-based NH temperature reconstructions [Jones et al., 1998; Mann et al., 1999; Crowley and Lowery, 2000] with model simulations of NH mean temperature changes over the past millennium based on estimated radiative forcing histories [Crowley, 2000; Gerber et al., 2002--results shown for both a 1.5Â°C/2*CO2 and 2.5Â°C/2*CO2 sensitivity; Bauer et al., 2003). Also shown are two independent reconstructions of warm-season extratropical continental NH temperatures [Briffa et al., 2001; Esper et al., 2002] and an extension back through the past two thousand years based on eight long reconstructions [Mann and Jones, 2003]. All reconstructions have been scaled to the annual, full Northern Hemisphere mean, over an overlapping period (1856-1980), using the NH instrumental record [Jones et al., 1999] for comparison, and have been smoothed on time scales of >40 years to highlight the long-term variations. The smoothed instrumental record (1856-2000) is also shown. The gray/red shading indicates estimated two-standard error uncertainties in the Mann et al. [1999] and Mann and Jones [2003] reconstructions. Also shown are reconstructions of ground surface temperatures (GST) based on appropriately areally-averaged [Briffa and Osborn, 2002; Mann et al., 2003] continental borehole data [Huang et al., 2000], and hemispheric surface air temperature trends, determined by optimal regression [Mann et al., 2003] from the GST estimates. All series are shown with respect to the 1961-90 base period.

This is from

Global Surface Temperatures over the Past Two Millennia