People have to decide, first of all, how they'd like to live, and how secure they want to be from disaster. After that, scientists can help determine what would be necessary to achieve that.

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

Here's the scientific community saying, fundamentally, "If we don't change our ways, we're screwed." And they got no attention at all. Even though the Union of Concerned Scientists put out this statement which was signed by more than half of all the Nobel laureates in science and another 1,500 distinguished scientists.

Anyone who opposes methods to control the birth rate, is automatically voting in favour having the death rate go up.

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.

After The Bomb we developed a fairly good system for moving food around and have avoided the kind of massive famines that attract the media. Although of course we've had a fair number of them, particularly in Africa, since The Bomb was written. But we have had a steady level of attrition of malnutrition and malnutrition-related disease. Probably something on the order of 5 to 10 million people starve to death each year, but they're spread out; they're not dramatic news events.

There's no question at all that the population explosion will come to an end. The two basic choices are it'll come to an end because we control our reproduction, and in many areas we have started to do so, or we'll end up with a high death rate. You have to take a personal moral stand on this.