As I admit in Bjorn Lomborg burns a few "witches", the media--and even researchers--can exagerate or trivialize global warming by focusing on the endless ramifications and possibilities.
How should we deal with this? When considering an issue, global warming or otherwise, I like to--at minimum--find the boundaries of the conversation or issue: when do I know that we are outside the bounds of sound analysis and reasonable discourse? For global warming, I propose the following:
Teacher: "Johnny, I see you didn't turn in your assignment. Did your dog eat it again?"
Teacher: "Then why didn't you turn it in?"
Johnny: "Global warming."
Though I'm sure someone can come up with a possible scenario, let's assume for the time being that "Global warming ate my homework" lies outside the bounds of reasonable global warming discourse.