There are a lot of signs. One of the things that makes me most nervous is the disappearance of the frogs. They're going downhill all over the planet. Frogs are susceptible to all kinds of problems, because they require water to breed and their skin is very porous. Their condition is nerve racking.

The drilling idea is spherically senseless - it's senseless from whatever point of view you look at it. It'd take 10 years to bring any oil online, and it would probably go to Japan. It sure wouldn't help gasoline prices here. All the economists say gasoline is still too cheap in the United States anyway. So here we're having this huge debate over offshore drilling that is just straightforward nonsense, which won't surprise you.

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.

Too many cars, too many factories, too much detergent, too much pesticides, multiplying contrails, inadequate sewage treatment plants, too little water, too much carbon dioxide - all can be traced easily to too many people.

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.

I see harm reduction as a way of engaging people as part of that path to recovery.

You take the huge income that comes with a big gas tax, and you use it to pay off regressive taxes like the FICA [Federal Insurance Contributions Act] tax. You can help the poor in other ways besides giving them cheap gas. You want to send the message that people want to be as efficient as possible using gasoline until we can transition away from that need entirely.