49 karma · joined April 13, 2013
Basic elemental analysis is very easy to fake, and very hard to demonstrate it was faked.
This correlation of data acquisition appears to have been done until the conversion of recording stations to MMTS stations. The correlation stop, at that point, and we are now entirely dependent on thermometer data. Coincidentally this is is also the 'hockeystick blade' time frame.
The data is still useful in determining the statistical confidence of the set, but not reliable for representation as its representation completely changes the understanding conveyed by the data set. So the data stays in, and the X-axis doesn't get trimmed. Only the data point, as represented in the last, non-robust interval, gets trimmed.
In fact the authors have used the instrumental record of the last 130 years to justify the incorporation of the statistically uncertain data from the last two centuries. From this we can understand their scientific model. They know their conclusions first, and then prove their conclusions. Good science is developing hypotheses and testing them.