Skiphil writes in comments:
“…there are some interesting developments in the “Marcott curve” which puts more of the circus in jeopardy. In addition to a new post on CA detailing changes in the core top record, there is this very significant comment on a prior thread which deserves some serious exploration:”
Jean S on “Marcott’s main plot (Figure 1A)”
Hah! There is some additional fun in Marcott’s main plot (Figure 1A). Mann’s hockey stick there is the global EIV-CRU from Mann et al. (2008), which means that there is no actual reconstruction post 1850, since it’s the Reg-EM produced EIV reconstruction! So they have now essentially “grafted the thermometer record onto” Mann’s reconstruction. To his credit, Mann has always been careful to plot the post 1850 part in EIV reconstructions in a different color. He is actually explicitly warning in his data description spreadsheet that the values for 1850-2006 are instrumental data.
So in Marcott et al Fig 1A we have a comparision in the interval 1850-1950 between their reconstruction (uptick) and Crutem3 (LAND only) (annual?) instrumental record (no uptick). But that’s not all, folks! See the associated uncertainties … Mann et al (2008) uncertainties (which seem to match in the plot to those given in the spreadsheet, i.e., 2 sigma, whereas Marcott et al uncertainties are 1 sigma) are naturally calculated only up to 1849 (as there is no actual reconstruction afterwards), but in the Figure 1A they continue all the way to the end. Where did those 1850-2006 uncertainties come from?
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