I reflect back 35 years ago, and look how far we have come in America with our environmental policy to improve the conditions of our air and water, and we have had some real successes.

All of the economic signals in the marketplace are essentially subsidizing the use of dirty fossil fuels and penalizing clean energy. There's really only one entity in society that can solve that problem, and that is government. And the air is a scarce resource.

We must start... rebuilding our cities around energy efficiency and human needs, rather than around the car and wasted energy.

I am not one for half measures or half-hearted efforts.

Tolerance is carved into the rostrum of the U.S. House of Representatives and intolerance should not be carved into the U.S. Constitution.

We can't tell China what to do if we don't do it ourselves. You don't inspire someone to take an action by refusing to take it yourself. We are in a race to be the dominant clean-energy provider to the world. Maybe this goes without saying: We've got to get China into an international protocol and the magic words are "common responsibility with differentiated action."

We allow it to be dumped into this community asset, which is our one and only atmosphere. So that has to change, and there's really only one entity that can do that. So we have proposed a cap-and-trade system to stop that unlimited pollution, to use the forces of the market to efficiently allocate scarce permits to allow CO2 into the atmosphere. That's just one of 500 things we need to do, but it's probably the granddaddy of them all.