It's coming home to roost over the next 50 years or so. It's not just climate change; it's sheer space, places to grow food for this enormous horde. Either we limit our population growth or the natural world will do it for us, and the natural world is doing it for us right now.

I don't think we are going to become extinct. We're very clever and extremely resourceful - and we will find ways of preserving ourselves, of that I'm sure. But whether our lives will be as rich as they are now is another question.

Steve Irwin did wonderful conservation work but I was uncomfortable about some of his stunts. Even if animals aren't aware that you are not treating them with respect, the viewers are.

The only acceptable way to solve ecological problems is if you can persuade people to have fewer children. In the Victorian times, there were families of 15 children. Someone like Edward Lear, he was the last of 21 children. And so what we have to think about is offering people the alternative choice. And in the West, that's what's happening. The birth rate has been dropping steadily and still is. I'm wanting human beings to be better off so they don't view children as an insurance for the future.

I have no doubt that the fundamental problem the planet faces is the enormous increase in the human population

This last chapter .. may have given the impression that somehow man is the ultimate triumph of evolution, that all these millions of years of development have had no purpose other than to put him on earth. There is no scientific evidence whatever to support such a view and no reason to suppose that our stay here will be any more permanent than that of the dinosaur.

There are perfectly good independent small nations.