Our Human Footprint

You've heard it a thousand times in recent years: being a citizen of the developed world — and especially a citizen of the United States of America — is bad for the planet. We all know we produce too much carbon, but it's hard to know exactly how, and how much.

Now a new documentary from National Geographic breaks down the impact of an American boy and girl on the environment, from the cradle to the grave.

The facts are dire. What we choose to do about it is another story.

This hour, On Point: The human footprint, your footprint, and what you can do about it.Guests:

Elizabeth Vargas, co-anchor of ABC News "20/20" and host of the National Geographic Special "Human Footprint."

Dr. Eric Sanderson, associate director of the Living Landscapes Program of the Wildlife Conservation Society and co-creator of the Human Footprint Map.

Colin Beavan, also known as "No Impact Man," he and his family conducted an experiment and tried for one year to leave no carbon footprint on the planet.