If humans disappeared, it would take about 100,000 years for the CO2 that we have pumped up to be reabsorbed. But most of it would be absorbed during the first few centuries. So, there is no question that if we started tomorrow, things would start to improve rather quickly.

We were all sold an idea by the founders of the Green Revolution, who were brilliant agricultural engineers, but very bad ecologists. They kept saying this is going to solve hunger on the planet, but any ecologist knows that the population of a species will always rise to meet the available food supply. That's exactly what has happened. That's why the population has doubled and re-doubled. Now we're faced with so many more people demanding so much more food, which requires so much more clearing of habitat and application of chemicals on the land.

The result is more demand for energy, more carbon in the atmosphere, and all of those fertilisers and shipping...obviously ‘stuff’ is spiraling out of control. We are created to make copies of ourselves. To control our numbers goes not against human nature; it goes against nature. But we now live on a planet where nature has to be managed. I'm not suggesting that we go out there and cull our numbers, like we do with Hangul and deer, so they don't eat everything up. But I am suggesting that we consider managing our production and nature in a way that we don't eat ourselves out of house and home, because that's what we are doing.