What Do You Say When Invited Back to Speak at Your Old High School?

That's the quandary I face tomorrow, when I'll be returning to New Orleans' Isidore Newman School--alma mater of, among others, Peyton and Eli Manning, Walter Isaacson, and Michael Lewis--to talk to the senior class. This isn't entirely a shot in the dark, as the seniors are taking a course on the environment, and I'm their speaker as they move into a section on Hurricane Katrina. So it's obvious that I'm to talk mostly about Storm World and the hurricane-global warming debate. At the same time, though, that won't suffice...roughly thirteen years ago, I was one of these seniors. I feel like I need to have something bigger to say to them, beyond being entertaining, beyond making jokes about pachyderm posteriors, and beyond explaining the hurricane-climate debate. I'm racking my brain, while also well aware that trying too hard to be profound is the worst thing I could do. So, I'm open to suggestions.....