Carbon is the fundamental element which all life on our planet is based on—but it's also much maligned for its role in climate change. So which is it, friend or foe?

The truth is: both. We've got a lot to be grateful for when it comes to carbon, but we also ought not pump too much more into the atmosphere. In this video, Crash Course describes the the complex Global Carbon Cycle and how it all works—from Carbon Fixation to Redox Reactions. [Crash Course]