I see our pal MikeYohe deftly sidestepped this, even though he acts like he’s very interested in correct paleoclimate data.
What, no, say it ain’t so. You say all he’s interesting in is Dr Mann bashing? Banish the thought. Mike do you hate Mann for political reasons?
Oh but let’s get back to the meat and potatoes because somewhere in there you finally got around to Dr. Lamm.
What do you know about Dr. Lamm and the work he was doing?
IPCC FAR 1990 Figure 7.1.c (red) based on Lamb 1965 showing central England temperatures;
(green dashed line) central England temperatures to 2007 shown from Jones et al. 2009.
(black) Also shown, MBH 1999 (global temperatures) 40 year average used in IPCC TAR 2001 (blue) and Moberg et al. 2005 low frequency signal .
1990 report (FAR)
See also: IPCC First Assessment Report
With the growth of interest in global warming in the 1980s came renewed interest in the past temperature record,
and the question of whether past times had been warmer or colder than "present".
However, at that time available records were few. The discussion in chapter 7 "Observed climate variations and change" of the last 1000 years
(excluding the instrumental period) occupies less than a page.
A schematic (non-quantitative) curve was used to represent temperature variations over the last 1000 years in chapter 7.
The vertical temperature scale was labelled as "Temperature change (°C)" but no numerical labels were given;
it could be taken to imply that temperature variations of the MWP and LIA were each of the order of 0.5 °C from the temperature around 1900.
The section specifically states recent climate changes were in a range of probably less than 2 °C.
The 1990 report noted that it was not clear whether all the fluctuations indicated were truly global (p 202).
The graph had no clear source (but can be traced to publications by Hubert Lamb representing the Central England Temperature;
those publications have no explicit calibration against instrumental data,
[and are] just Lamb’s qualitative judgement and interpretation of what he refers to as the ‘evidence’ ),
and disappeared from the 1992 supplementary report.
That is how the MWP was disappeared Mr. Yohe.
Please note, MBH 1999 does indeed show a MWP, if not as dramatic as some ignorant minds believe it should be.
Gotta follow the data dude.