In human behavior, when people have stated a position that they believe to be true, they are subsequently loath to admit error, even in the face of overwhelming evidence to the contrary. To be wrong, is in a sense, to sense shame or failure.
But the fact is, we’re all wrong from time to time. We’re all human and make mistakes in our reasoning and our understanding. I don’t think there’s any shame in admitting that I was wrong about something, that I am wrong now about things that I currently believe, or that I will be wrong in the future. Human history is replete with demonstrations of clear error and mistaken reasoning.
The true error is never to admit that fallibility, especially when it comes in an area with which you are most skilled and most recognised. You have a reputation to maintain, a professional dignity to uphold. But reputations are destroyed, not because of mistakes or errors, but because of the inability to admit error and mistakes. For an example of this sort of phenomenon, see the works of James "The Amazing" Randi in such books as "Flim-Flam", or look at what happened to the scientific careers of Pons and Fleischmann or Jacques Benveniste.
Thus, it’s quite refreshing that someone like Ulrich Cubasch can re-examine his former beliefs about a particular part of climate science, and change his stated position in the light of new evidence and further investigation. Of course that further investigation involves our favorite reconstruction of past climate. Note that this does not mean that Ulrich Cubasch does not believe in future man-made climate change.
Here is Ulrich Cubasch’s expressed position on climate change published in 2001. Now unfortunately it’s in German, but using babelfish you should get a fair idea of what is being discussed.
And here’s that graph again, "up front and center" as Steve McIntyre put it, linking past climate change to future "anthropogenic global warming" by those climate model projections:
I always wonder, when looking at graphs like this, how anybody could claim (like Andrew Weaver) that the Medieval Warm Period and the Little Ice Age are recorded in them. But that’s because I’m not a PhD, so I must not be seeing things the same way.