Several months ago, I bought Leonardo Dicaprio's documentary 11th Hour at Wal-Mart for $1. (Yes, I do occasionally shop at Wal-Mart.) I am sorry I waited so long to watch it. If you can find a copy, get it.
I'm a systems thinker. That was the focus on much of my early education in biology and that is the way I see and understand the world. This documentary does a pretty clear job of explaining how our actions in one area impact other areas. It clearly explains the concept of our dependence upon "ancient sunlight" (carbon fuel), especially it's impact on the ability for the earth to support the large population we have now (as well as its impact on climate, food supplies, and health.) It also focuses on the impact of chemicals on health, deforestation, soil depletion, and other environmental issues.
Next the film focuses on the forces that block change, such as our legal system, large corporations, our political system, and most importantly our consumptive culture. (One statement that caught my attention is that for every 1 truckload of valuable goods, we produce 32 truckloads of waste--isn't that insane?)
Anyway, the film is not just a catalog of problems, but discusses a way to go forward. As one of the experts says, "What a great time to be born. What a great time to be alive, because this generation gets a chance to essentially completely change the world." With my background in biology, the examples of using organisms our teachers in sustainable technologies was especially interesting. The film brings it home with a call to action for individuals.
In sum, find the DVD and watch it. Invite your friends.