Here's one of the emails he lists:
SUBJECT: Please remove my name from AMEG web page
Ken Caldeira <kcal...@carnegie.stanford.edu>
5/3/12
to John, Thomas, Michael
John,
I do not think the evidence for a powerful feedback involving arctic warming and catastrophic methane release has been established, nor do I think there is substantial evidence supporting this perspective.
I do not think it has a zero chance, but in IPCC parlance I would suggest it is very unlikely, if not exceptionally unlikely.
However, I do not pretend to great expertise in this area, so my assessment of probabilities should bear little weight.
In any case, I already make enough reckless statements myself that I do not see benefit to myself of being associated with other people's reckless statements.
I find you to be a sympathetic man and I bear you no ill will. I have plenty of friends with whom I disagree, but I don't want to be associated with their comments either.
Regards,
Ken