Poor warmists: In 2007, they were trying to figure out what to do about a critical 1990 IPCC graph that looks nothing like the hockey stick

2007 email from William M. Connolley

In any case, the graph has no objective basis whatsoever; it is purely a "visual guess" at what
happened, like something we might sketch on a napkin at a party for some overly persistent
inquisitor.....[Ray Bradley] I believe this graph originated in a (literally) grey piece of literature that Jack Eddy used to publish called "Earth Quest".
[tom crowley] we still don't have an adequat explanation as to how Jack "cooked up" that figure

email from Rasmus Benestad

I think that this story could possible catch on and make headlines, so I
agree that we should be careful... There are sometimes a few rotten apples in a good batch,
unfortunately. But the important part is that we don't accept rotten
apples and that we sort it out! Forthcoming and up-front.

Email 1497--Rahmstorf

I also see your problem: what we are finding out now makes the IPCC
process look somewhat unsophisticated back in 1990, so it is a
diplomatic conundrum how to be completely truthful in reporting this, as
we need to be as scientists, without providing the skeptics undue fodder
for attacking IPCC.

Where did IPCC 1990 Figure 7c Come From? « Climate Audit

So I think that we have a solution to the provenance of IPCC 1990 Figure 7c. It is derived from the rounded CET from Lamb 1965 Figure 3 top panel, with portion after 1400 smoothed somewhat. It has been converted to anomaly deg C (using the average of the entire period) and extended to include the average CET for the period 1950-1984.