I'm not an expert when it comes to technology, but what changed things for me was autofocus. I used to have to throw away half my pictures because it was so difficult to get the focus right.

I always take hundreds and hundreds of pictures. I used to work for 'National Geographic,' and they gave us a lot of film.

The Rio Earth Summit in 1992 changed my life completely, turning me into an activist. From the air, you see things you can't see from the ground - you really understand the impact of man, even in a place you know well. My work is meant to convince people we can no longer live like this.

For me, an aerial picture is no different than a close-up portrait. It's a question of framing and angle. Helicopters are great for that. But I've also used planes. Of course, I always have a harness.

To have success in your professional life is not so hard. To succeed as a man is more difficult.

I wanted to be a scientist. I did a thesis on lions. But I realised photography can show things writing can't. Lions were my professor of photography.