It's
Matt Ridley versus
David MacKay. Both parties agreed on a number of scientific issues, including that the role of clouds in warming is not well understood.
Ridley makes some good overall points on skepticism of scientific consensus, pointing to his own alarmism over acid rain in the past, and the difficulty of making quality decisions to affect a technologically different future. It's nice to see a debate where constructing straw men is avoided as much as possible.