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.

Organisms are starting to move in response to climate change all over the place. Bees are disappearing and we don't have many of the native pollinators left to replace them. We're in deep trouble; there's no question about it. But ecologists tend to think of something that's going to be bad in ten years as very fast, and of course, politicians only think of things in a two-, four-, six-year cycle.

I'm sort of optimistic about what we could do, but I'm very pessimistic about what we will do. I can't tell you that Al Gore's 10-year plan is impossible. I'm old enough to remember the Second World War - if we had a World War II-type mobilization, we might accomplish Gore's plan. In 1940 we were making tens of thousands of automobiles, and in 1941 we were making tens of thousands of airplanes. We mobilized as a nation. If we get that kind of mobilization as a nation or globally, then we could solve a lot of these problems.

Overall, The Population Bomb was probably too optimistic. I was writing about climate change - Anne and I actually wrote the book. We discussed whether or not you'd have to take a gondola to the Empire State Building, and that sort of thing, but we didn't know at the time whether the climate change would be in the direction of heating or cooling. We just didn't know enough about it.

I would take even money that England will not exist in the year 2000.

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

So, regarding the time frame, I'm only too willing to admit that my crystal ball, like everybody else's, is cracked. If I could predict precisely, I would have started predicting the stock market and would now be living with a bunch of young women on Bora Bora, having bought it.