In the mid- to late-90s, there were a slew of papers (e.g. Costanza et al. 1997; Pimentel et al. 1997) estimating the economic value of global biodiversity. Estimates ranged from about $16 to $54 trillion. At that time, world GDP was about $30 trillion. So, a question: has human economic output finally exceeded natural economic production? When? Did anyone even notice that it happened?
p.s. A mountain lion was shot and killed near Chez Panisse earlier this week [thanks Clare].