People sometimes say we need to be really almost on a wartime footing if you want to change. Our whole economy is based on burning fossil fuels, which is taking CO2 out of the ground and putting it up into the air.

Even very smart people can try to shoehorn new information that just doesn't fit into an existing paradigm.For a long time the story that we've been telling ourselves is that humans are just another animal. We evolved from other animals and our place in the universe isn't particularly special. What I'm trying to convey in my book [The Sixth Extinction] is that we are unusual.

We have all this Paleolithic art that suggests that our ancestors really venerated animals and that they depended on wild animals to survive - as opposed to domesticated animals that we depend on. Would it radically change things if we had more rhinos in our midst? I kind of suspect it would.

You're an animal that needs to move across the landscape, you can't anymore, and that's another way we're just changing the surface of the Earth in very dramatic ways.

I don't think there are too many places left that humans haven't pretty thoroughly explored.

You've got to do everything, everything's got to be pointing in the same direction and you've got to really turn this whole economic engine from one that's based on fossil fuels to one that isn't.

Most of the world's major waterways have been diverted or dammed or otherwise manipulated - in the United States, only two per cent of rivers run unimpeded - and people now use half the world's readily accessible freshwater runoff.