Guest: Eric Roston.

Carbon has always been seen as the ubiquitous building block of life, necessary to the rise of living organisms. But since the start of the industrial age, carbon has contributed to the destruction of the ozone layer. Today on Focus, we're joined by journalist Eric Roston, author of The Carbon Age. He'll talk about the ways humans have used carbon throughout history and how it's only now, at the brink of catastrophe, that we are beginning to recognize the effects it has had on our environment.