The human population can no longer be allowed to grow in the same old uncontrollable way. If we do not take charge of our population size, then nature will do it for us and it is the poor people of the world who will suffer most

If we and the rest of the back-boned animals were to disappear overnight, the rest of the world would get on pretty well. But if the invertebrates were to disappear, the world's ecosystems would collapse

Its about cherishing the woodland at the bottom of your garden or the stream that runs through it. It affects every aspect of life.

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.

Nature isn't positive in that way. It doesn't aim itself at you. It's not being unkind to you.

There's a small worm called Loa Loa Filariasis. This parasite can survive in one environment exclusively- namely, underneath the skin and inside the eyes of human beings. Children and the elderly in tropical regions (usually the poorest) are the most widely affected. A painful, slow death is virtually certain. The worm can actually live in the host for 17 years before the host finally dies.

Climate change will affect the whole of humanity, while terrorist attacks will only affect a small section of humanity. Of course, you wouldn't say that if you were related to someone who had been beheaded or blown up or murdered. But humanity is facing a very big, slow, long, drawn-out threat, and that is to do with the way the weather is changing and the size of the population.