The future of life on earth depends on our ability to take action. Many individuals are doing what they can, but real success can only come if there's a change in our societies and our economics and in our politics. I've been lucky in my lifetime to see some of the greatest spectacles that the natural world has to offer. Surely we have a responsibility to leave for future generations a planet that is healthy, inhabitable by all species

The fact is that no species has ever had such wholesale control over everything on earth, living or dead, as we now have. That lays upon us, whether we like it or not, an awesome responsibility. In our hands now lies not only our own future, but that of all other living creatures with whom we share the earth.

They always mean beautiful things like hummingbirds. I always reply by saying that I think of a little child in east Africa with a worm burrowing through his eyeball. The worm cannot live in any other way, except by burrowing through eyeballs. I find that hard to reconcile with the notion of a divine and benevolent creator.

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

I think a major element of jetlag is psychological. Nobody ever tells me what time it is at home.

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.

Can a growing human population still leave space for wildlife?