"Evidence is all," said the skeptic. "So tell me," he said, staring at the pellucid liquid in his ice cold martini, "given that there's been no warming now for nearly a decade, what do you suggest are the four strongest pieces of evidence supporting your hypothesis of man-made global warming? And what are the four strongest pieces of evidence that any warming, whether man-made or natural, would be catastrophic?"
What's your answer? Keep it brief.