The benefits human civilization enjoys from the world’s natural ecosystems — grasslands, marshes, coral reefs, forests, and the like — amounts to something in the vicinity of $142.7 trillion a year. That’s over eight times the value of the entire U.S. economy ($16.2 trillion a year), and almost twice the value of the world economy ($71.8 trillion a year).
http://thinkprogress.org/climate/2014/06/09/3446662/natural-capital-142-trillion/
