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

What humans do over the next 50 years will determine the fate of all life on the planet.

Now, I find that very difficult to reconcile with notions about a merciful God.

I've never actually met one in the wild, but I have seen a king cobra. They go towards people, they rear up six feet tall and they're very aggressive and they are very fast. And one bite means certain death. So if I encountered a king cobra in the wild I would be very alarmed.

Fundamentally not to waste energy. If we were all to reduce our demands for energy, it would make an enormous amount of difference.

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.

Before the BBC, I joined the Navy in order to travel.