Historically, things were moving in a pretty good direction until the Reagan presidency. And then it all got reversed. The Mexico City policy was instituted - the idea of wrecking the environment for this generation's profit and forgetting about our gets got firmly embedded. I'm sad to say the Clinton administration didn't turn it around and the Bush administration, well, I think they're the worst administration we've ever had, and I used to be a Republican.

There are substitutes for oil; there is no substitute for fresh water.

Woman should have the choice whether to have an abortion or not, but I like what Bill Clinton said: It ought to be safe and rare. You don't want to offend people with it. You try and do as much as you can to let people be different, but also to try and protect them from things that they think are bad. And it's worth all of us giving a little.

Stanford may be the best university in the world, but you can get all the way through here without knowing where your food came from, without being able to say where we came from, without being able to give a coherent description of why the climate is changing and why we should be concerned about it. So I started teaching a course in human evolution and the environment that's open to all Stanford students, no prerequisites.

In pushing other species to extinction, humanity is busy sawing off the limb on which it perches.

I thought if the climate was heating that CO2 was the only forcing, and it would be late in the century before we had trouble. Now that we know about the other half of the forcing, it's obvious that the trouble is coming much sooner.

We ought to take good care of everybody we have on the planet, but we ought to regulate the rate at which people join us. The old saying is, "It's the top of the ninth inning, and humanity has been hitting nature hard, but you've always got to remember that nature bats last."