There's lots about politics I don't feel comfortable with. To talk about the politics of future ideas is impossible in soundbite form.

Global warming, along with the cutting and burning of forests and other critical habitats, is causing the loss of living species at a level comparable to the extinction event that wiped out the dinosaurs 65 million years ago. That event was believed to have been caused by a giant asteroid. This time it is not an asteroid colliding with the Earth and wreaking havoc: it is us.

Junkies find veins in their toes when the veins in their arms collapse. Developing tars sands is the equivalent.

I flew on Air Force Two for eight years, and now I have to take off my shoes to get on an aeroplane.

Each and every one of us can make changes in the way we live our lives and become part of the solution [to climate change]

There's an old African proverb that says "If you want to go quickly, go alone. If you want to go far, go together." We have to go far - quickly. And that means we have to quickly find a way to change the world's consciousness about exactly what we're facing, and why we have to work to solve it.

I've been dreaming of this moment since I was a kid growing up in Tennessee: that one day, I'd have the chance to come here to Madison Square Garden and be the warm-up act for Elvis.