If you're a conservation biologist in many fields, you're seeing your study subject disappear. People are in the position where they're chronicling radical decline, and that is not a position that conservation biologists want to be in.

Well in the scientific there is virtually no debate over certain things. For example, that we are changing the world. Humans are changing the world very radically, very dramatically. Climate change, which I assume is one of the points you're alluding to, is at the heart of this.

Some of these species that are now no longer with us were killed off by a fungal disease that was moved around the planet by people.

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.

For a long time, science has gone in the direction of sort of putting people in their place. We learned that the sun doesn't revolve around the Earth, the Earth revolves around the sun; we learned that we're just another species, evolved, like all other species, so we're just another animal, really.

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.

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