Since Chefen has brought this figure into play, there’s much to consider about it. [Also see followup here.] For interested parties, the data is at WDCP here . I haven’t got to checking Chefen’s results yet, but wanted to table interesting results in passing. As Jean S noticed, the Corrigendum stated that an “old” version of the reconstruction was used in these calculations, but it didn’t “matter”. I’ve plotted the two versions together and, for the purposes of his correlations, the difference between the two versions probably doesn’t “matter” but it’s worth wondering why the two versions differ. Secondly, Figure 7 contains a splice of instrumental and proxy records, which presumably carry forward into the correlations. I’ll review what Mann has said in the past about such splices.
First here is the original Figure 7 shown in full with original caption. Notice the change in the line at the right of the top panel and the caption. Mann has here spliced the proxy reconstruction with instrumental data from 1980-1995.
Original Caption. Figure 7. Relationships of Northern Hemisphere mean (NH) temperature with three candidate forcings between 1610 and 1995. Panels, (top to bottom) as follows. “ÅNH’, reconstructed NH temperature series from 1610–1980, updated with instrumental data from 1981–95. “ÅSolar’, reconstructed solar irradiance. “Ålog CO2′, greenhouse gases represented by atmospheric CO2 measurements. “ÅDVI’, weighted volcanic dust veil index. Bottom panel, evolving multivariate correlation of NH series with the three forcings NH, Solar, log CO2. The time axis denotes the centre of a 200-year moving window. One-sided (positive) 90%, 95%, 99% significance levels (see text) for correlations with CO2 and solar irradiance are shown by horizontal dashed lines, while the one-sided (negative) 90% significance threshold for correlations with the DVI series is shown by the horizontal dotted line. The grey bars indicate two difference 200-year windows of data, with the long-dashed vertical lines indicating the centre of the corresponding window.
The next figure compares the “old” and “new” versions of the MBH reconstruction. The range of differences is from -.2 to 0.27. I wonder how this is dealt with in confidence interval calculations. The blue on the right shows the spliced instrumental record.
Top: black – “Old” reconstruction; red- “new” reconstruction; – blue – instrumental splice.
No researchers in this field have ever, to our knowledge, “grafted the thermometer record onto” any reconstruction. It is somewhat disappointing to find this specious claim (which we usually find originating from industry-funded climate disinformation websites) appearing in this forum.
I had discussed in a previous post a splicing of proxy and instrumental records executed by Crowley and was able to show convincingly that Crowley had effected the type of splice that Mann said no one, to his knowledge, had ever done. I then pointed out that Mann had switched Crowley versions between Mann et al (Eos 2003) and Jones and Mann 2004, using an unspliced Crowley version in the latter. I surmised that the Eos 2003 spaghetti graph (and these spaghetti graphs are hard to read) contained a spliced Crowley version and that Mann knew this, calling the above claim into question.
Lambert examined the Eos graph and suggested that the graph shown as being from Crowley was actually a displaced version of the MBH99 reconstruction and it was simply another Mann screw-up, but did not provide evidence that Mann “knew” of the Crowley splice. Since Mann has not issued a corrigendum explaining exactly what the screwup in Eos 2003 was, it’s impossible to know for certain – this is the Hockey Team. However, I agreed with Lambert that it might have been simply yet another Mann screwup and did not show that Mann mis-spoke at realclimate.
However, here we have a splice in Mann’s own work, in MBH98 itself no less. How can someone reconcile the splice in Figure 7 and related Supplementary Information with the claim that “No researchers in this field have ever, to our knowledge, “grafted the thermometer record onto” any reconstruction “? I’m sure we’ll find out soon enough. Lambert’s pretty resourceful at explaining away his client’s DNA.