Thanks to the Manhattan Contrarian for providing a March update on the eight-year long legal action conducted by M. Mann against M. Steyn.  His post is Update On Michael Mann v. Mark Steyn Litigation.  Excerpts in italics with my bolds and images.

Mann’s central allegation in his case against Steyn is that this passage is defamatory because the “hockey stick” graph is not “fraudulent”; and therefore Steyn’s statement that the graph is “fraudulent” is false.

Remarkably, eight and a half years into this case, only now is the truth or falsity of the claim that the “hockey stick” graph is fraudulent being addressed.

The issue was finally raised in a motion for summary judgement filed by Steyn on January 22 — although almost as an aside, in a motion dealing with many other issues; and then the issue was much more squarely addressed in a response by Steyn to a motion for summary judgment by Mann, filed by Steyn on March 3. I have been sent a copy of the March 3 filing, but I have not been able to find a link for it online.

The Steyn motion papers point to three ways in which the Hockey Stick graph is fraudulent.

1.  Mann Deleted Data Adverse to the “Hockey Stick” Shape

Of the three, the most compelling is the deletion by Mann of certain adverse data that would have destroyed the neat “hockey stick” shape of the graph. The graph shows a reconstruction of world atmospheric temperatures from about the year 1050 to 2000, where the first 900 years have temperatures flat or slightly declining, followed by a sharp upward move in the last 50 or so years. The 900 year flat period was derived from several collections of data from tree rings, one of which was provided by a Mann colleague named Keith Briffa. However, in the most recent years (post-1960) the Briffa series showed a decline in temperatures — an inconvenient fact that would have greatly undermined the intended visual impact of the graphic. Mann then decided simply to delete the portion of the Briffa data post-1960, while still using the rest. From the Steyn March 3 submission:

The [Hockey Stick graph as published in the IPCC’s Third Assessment Report in 2001, in a portion written by lead author Mann] omitted tree ring proxy data collected by climate scientist Keith Briffa that showed a decline in temperatures after 1960, a message inconsistent with the prized hockey stick shape. . . . The IPCC TAR did not disclose the deletion of this data. . . . As lead author, Mann decided to omit the Briffa data without the input of his other lead authors.. . . Mann’s own collaborators cautioned him against the deletion. IPCC TAR Coordinating Lead Author Chris Folland wrote to Mann that Briffa’s data “contradicts the multiproxy curve and dilutes the message rather significantly.”. . . Briffa himself urged Mann not to succumb to “pressure to present a nice tidy story” by “ignor[ing]” his post-1960 results. . . . Mann agreed with them on the merits but bemoaned the data’s political impact: “[I]f we show Keith’s series . . . skeptics [will] have a field day.” . . . To prevent a “skeptics’ field day,” he chose to delete the data.

One would think that this is about as clear a demonstration of scientific fraud as it is possible to have.

2.  Mann “Cherry-Picked” Data to Show Flat Temperature Trend

3. Mann Showed One Record Upside Down to Support the Desired Shape

And as indicated, this is just one of three instances of fraud in the Hockey Stick graph that are set forth in detail in Steyn’s March 3 submission. The other two involve: (1) “cherry picking” of data, in the selection of proxy data series to show a flat-to-declining temperature trend from 1050 to 1950, by simply omitting to use any of the many available series that show the existence of a “medieval warm period” warmer than the present, and (2) misinterpreting one series to use the results upside down and then, when the error was pointed out, continuing to use the series in that way because it supported the desired visual presentation.

The original MBH graph compared to a corrected version
produced by MacIntyre and McKitrick after undoing Mann’s errors.

Anyway, Mann gets to throw at least one more brief into this mix, and then we will await the court’s decision. As clear-cut as this may appear from the excerpt I provided, the court’s decision could well not come out until late in the year. If sumary judgment is denied, there will then be a trial. Another possibility is that the court grants summary judgment to Mann as plaintiff. I find that possibility almost too ridiculous to contemplate, but the fact is that when things get as politicized as the “climate change” thing has become, the human mind loses almost all rational capability.

Background: Rise and Fall of the Modern Warming Spike

The first graph appeared in the IPCC 1990 First Assessment Report (FAR) credited to H.H.Lamb, first director of CRU-UEA. The second graph was featured in 2001 IPCC Third Assessment Report (TAR) the famous hockey stick credited to M. Mann.