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jck101: [referring to my approach to determining the temperature range] This seems like a not great way to do it since if you pick another study you can easily move your range 50%, maybe more, change the years, you can do the same, plus the uncertainties are most likely underestimated.

This is just a first pass, with the goal of seeing whether or not the pre-industrial temperature fluctuations are consistent with intrinsic solar variability as their source (and I conclude hey are). It is, as you (and Loren) say, not the best approach. Ideally you want to regress temperature reconstructions and TSI reconstructions for the period in question (800-1850 AD) in order to get a more robust climate sensitivity. The problem is that there are no good reconstructions of either quantity available at present. The Mann study (aside from DB2's objections) is only a northern hemisphere reconstruction, so it is limited. Although the study does include a global land + ocean reconstruction in the appendix, it only goes back to about 1400 AD. I plan to do the full analysis when the PAGES 2k ocean temps reconstruction is completed, and I've had the chance to come up with the best TSI reconstruction. So regard the present analysis as a "back-of-the-envelope" first pass.

DB2: Phil, I can't believe you used Mann 2008. That study used some proxies upside down, was overly dependent upon bristlecone pines which have numerous problems and, IIRC, the study was statistically shown to be invalid before about 1400. Pick another reconstruction; almost any would be better.

I used Mann et al. (2008) because they present (in their Fig. 3) an ensemble of (at least 16 different) reconstructions and historical data. The spread among the various reconstructions gives one a good sense of the uncertainties involved in each of the individual reconstructions. Even if any one particular reconstruction is problematic, the overall mean or, better, median value for any year should be reasonably robust. I didn't actually use the Mann et al. reconstructions presented in the appendix. Rather I just "eyeballed" the median of the ensemble of reconstructions presented in their Fig 3. Again, my goal was merely to see if interpreting pre-industrial temperature fluctations as being due to solar variability made sense. And it really does seem to.

I expected to get flak over the use of Mann data. The fact remains that this work is a major compilation of climate reconstructions, published in the PNAS (Proceedings of the National Academy of Science), and linked to from the NOAA site. I trust the NAS and NOAA. As a working scientist, I don't have time to second-guess every published result, especially one as distant from my own research field as this. You simply have to trust published material from credible sources (unless you have particular reason to suspect otherwise), or you'd never get anything done. That doesn't mean I uncritically accept every claim made. But generally I will accept the results of a paper published in a major journal, especially after several years in press, and if it's outside my particular area of expertise. If something is really wrong, you would definitely know about it by then. That's not to say that journals don't get it wrong sometimes. I remember a major paper in Nature a few years back that nearly made the cover (it ended up being a runner-up). It was basically a good paper, but there were some blatantly incorrect assertions made in the paper. Over time, these have been mostly addressed elsewhere in the literature. And that's typical of the game -- science is mostly a self-correcting enterprise because there is a lot of personal prestige and reputation wrapped up in ensuring that this is the case.

Phil
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