16. if one dates the Industrial Revolution to 1800?
The planet's human population has increased sevenfold in that time. There were about a billion people on the planet at the dawn of the industrial revolution; it took 130 years for that number to double to 2 billion. The next increase of 2 billion took just 45 years. And the next, just 25. We probably passed sustainable carrying capacity around 1960 or so. Like Bill Hicks said: "People suck. We're a virus with shoes."