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 would be absolutely astounded if population growth and industrialisation and all the stuff we are pumping into the atmosphere hadn't changed the climatic balance. Of course it has. There is no valid argument for denial.

I think the most alarming animals I have encountered are really poisonous snakes.

I often get letters, quite frequently, from people who say how they like the programmes a lot, but I never give credit to the almighty power that created nature.

You can cry about death and very properly so, your own as well as anybody else's. But it's inevitable, so you'd better grapple with it and cope and be aware that not only is it inevitable, but it has always been inevitable, if you see what I mean.

It seems to me that the natural world is the greatest source of excitement; the greatest source of visual beauty; the greatest source of intellectual interest. It is the greatest source of so much in life that makes life worth living.

I just wish the world was twice as big and half of it was still unexplored.