Episode 10 - Thinking Like a Planet

Earth is a unified natural system that's been in continuous operation for 4.6 billion years.  It's most important subsystem on land is the called the critical zone, which extends from the top of the vegetation canopy to the base of circulating groundwater. This is the subsystem where rock, water, soil, biota, air, and humans are hopelessly entangled.

 

Thumbnail image from NASA.