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.

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.

The fact is that seven per cent of the global population emits 50 per cent of greenhouse gas emissions, and the proportions are the same for the use of energy and raw materials, meat, wood, etc. Simply put, an infinitesimal minority consumes the most and imposes damage on the overwhelming majority, while asking it to change.

The West has become the world model; developing countries are dreaming of living like us, which is impossible. They should reject our model, because it is not sustainable. Developing countries should even give us the example, but unfortunately that's not what happens.

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

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.

I learned to be a hot-air balloon pilot to take tourists over the Masai Mara Reserve in order to earn some money and finance the work I was doing with my wife, Anne. We were studying the life of a family of lions for more than two years. Taking pictures was a way to capture information we could not put in words.