From Dr. Roy Spencer, PhD

ETA: Here is Dr. Spencer's answer to a comment posted in response to his post above:
Yes, some things have more confidence than others in science, so point taken.

But the cause of recent warming is not one of the very high confidence ones that approach the level of “scientific proof”, when almost all climate models cannot even explain (as a hindcast!) how little warming there has been since we’ve monitored global temperatures on a truly global basis (since 1979).

So, even with a less restrictive definition of “scientific proof”, AGW fails. Not that it’s wrong…we simply don’t know.

The question was sufficiently ambiguous that it constituted a “trap”: Brown could hear the question one way, the asker probably meant something else.