A sense of urgency and a great opportunity
All of the links in Glen's posting are worth checking out, but you may not find too much new in Leggett's lecture if you're familiar with basic arguments about climate change and peak oil.
I do encourage you to watch the entire Al Gore segment, though. What I find important there is his careful, passionate, and, yes, somewhat optimistic reframing of the issues we face. Do check it out, and then let me know what you think.