If you consider that there are a million people forced out of their homes by Katrina, multiply that by 150, and then stick those people in countries who, as inconceivable as it seems, are less prepared than we were to deal with the whole thing.

It's our own throat that we are cutting in the end along with everyone else's. We need to be exercising precisely the kind of leadership that might allow us to nudge China and India, say, onto different energy trajectories, in order to improve our own chances of surviving this century.

I don't know how to make people who absolutely have to be obsessed with paying a week's energy bills... obsessed with climate change... It's very hard.

To me, it's more important to take the 60-70% of people who really understand that there's a problem [of climate change] and get some percentage of them active than to try and stamp out the last embers of pre-scientific thought.

My guess is that liberating the fossil fuel industry to frack anywhere they want will drive down the rate at which we're converting to sun and wind. And it's entirely a rate problem at this point.

It was huge mistake to avoid working with the rest of the world because (a) we're the largest source of the problem: 4% of us who are in the U.S. produce 25% of the world's carbon dioxide.

Climate change is the single biggest thing that humans have ever done on this planet. The one thing that needs to be bigger is our movement to stop it.