There is no question that climate change is happening; the only arguable point is what part humans are playing in it.

Human beings, because we're so clever, have removed every single one of those population limiting factors... So nothing controls our increase in numbers except our own wish. Since I first started making television programs, the population of the world has increased three times. That's an extraordinary notion. Can it increase four times? Can it increase five times? The Earth is a finite size. So a point will eventually come when we run out of food, when we run out of space and when we will have destroyed most of the natural world. So ought we to do something about it before that happens?

That people will object very much to seeing a predator killing its prey, and yet, in the news, will accept showing shots of people shooting one another.

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

I'm no longer sceptical. I no longer have any doubt at all. I think climate change is the major challenge facing the world.

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

I suffer much less than many of my colleagues. I am perfectly able to go to Australia and film within three hours of arrival.