Scientists tend to focus on what they don't know more than what they do know. And there are a lot of things we still don't know about the climate. But we know the difference between climate variability and climate change, and right now the amount of carbon in the atmosphere is well outside the variability pattern - and that's quite quantifiable.

C'mon kids! Wake up and smell the CO2! Take over your administration building, occupy your university president's office, or storm in on the next meeting of your college's board of trustees until they agree to make your school carbon neutral.

We've gone from thinking the fuels that powered our growth were inexpensive, inexhaustible and benign to understanding they are exhaustible, expensive and toxic. Once you frame the problem that way, people will look at solutions differently.

America is interested in change and reform in the Middle East but in a stable way.

I was in Bangalore, India, the Silicon Valley of India, when I realized that the world was flat.

Iraq today does have a chance to shape its own future. They may not do that, or this generation may not do that. But maybe the next one will, I don't know. They may try and fail, and stumble, get up and fall back.

Communism was a great system for making people equally poor - in fact, there was no better system in the world for that than communism. Capitalism made people unequally rich.