CNN takes viewers around the world in a two-part, four-hour documentary that examines our changing planet. This worldwide investigation, shot in high definition, looks at four key issues: climate change, vanishing habitats, disappearing species and human population growth.

To tell this story, Anderson Cooper, Dr. Sanjay Gupta and Animal Planet's Jeff Corwin traveled to some of the most remote and remarkable places on Earth. From exposing illegal wildlife trading undercover in Southeast Asia to seeing first–hand the devastating effects of deforestation in Brazil, they have gathered evidence on the unsettling changes taking place all around us.

Get a sneak peak of this dramatic documentary, featuring the exclusive new song from R.E.M., "Until the Day is Done".

Watch trailer with music from R.E.M.

Go behind the scenes with the crew

Watch outtakes