"The type of arguments this person likes to make" seems ad hominem to me. Being wrong about global warming doesn't make him wrong about this unrelated topic. A

"The type of arguments this person likes to make" seems ad hominem to me. Being wrong about global warming doesn't make him wrong about this unrelated topic. Also, his coauthor on the current book has impeccable credentials as perhaps the leading honest broker in the field, so these comments feel a bit like looking for a weak flank to attack.