| Leonardo DiCaprio | ... | Himself - Narrator |
 | Kenny Ausubel | ... | Himself - Founder, Bioneers |
| Thom Hartmann | ... | Himself - Author, The Last Hours of Ancient Sunlight |
| Wangari Maathai | ... | Herself - Founder, Greenbelt Movement, 2004 Nobel Peace Prize Laureate |
| Sandra Postel | ... | Herself - Director, Global Water Policy Project |
| Paul Stamets | ... | Himself - Mycologist, Author, Mycelium Running |
| David Orr | ... | Himself - Chair, Environmental Studies Program, Oberlin College |
| Stephen Hawking | ... | Himself - Lucasian Professor of Mathematics, Cambridge University |
| Oren Lyons | ... | Himself - Faithkeeper, Turtle Clan, Onondaga Nation, Haudenosaunee, Six Nations, Iroquois Confederacy |
| Andrew C. Revkin | ... | Himself - Author & Science Reporter, New York Times (as Andy Revkin) |
| Sylvia Earle | ... | Herself - Oceanographer, Explorer-in-Residence, National Geographic Society |
| Paul Hawken | ... | Himself - Author, Environmentalist, Entrepreneur |
| Janine Benyus | ... | Herself - Author, Biomimicry |
| Stuart Pimm | ... | Himself - Professor of Conservation Ecology, Duke University |
| Paolo Soleri | ... | Himself - Architect, Founder of Arcosanti |
| David Suzuki | ... | Himself - Scientist, Environmentalist, Broadcaster |
| James Hillman | ... | Himself - Psychologist |
| James Parks Morton | ... | Himself - Dean Emeritus, The Cathedral of St. John the Divine |
| Nathan Gardels | ... | Himself - Editor, New Perspectives Quarterly |
| Wes Jackson | ... | Himself - President, The Land Institute |
| Joseph Tainter | ... | Himself - Author, The Collapse of Complex Societies |
| Richard Heinberg | ... | Himself - Author, The Party's Over: Oil, War and the Fate of Industrial Societies |
| James Woolsey | ... | Himself - VP, Booz Allen Hamilton, Director, CIA, Central Intelligence Agency, 1993-1995 |
| Vijay Vaitheeswaran | ... | Himself - Energy & Environment Correspondent, The Economist |
| Brock Dolman | ... | Himself - WATER Institute Director, Occidental Arts & Ecology Center |
| Stephen Schneider | ... | Himself - Co-Director, Center for Environmental Science & Policy, Stanford University |
| Bill McKibben | ... | Himself - Author, Founder, Stepitup07.org |
| Peter de Menocal | ... | Himself - Associate Professor, Lamont-Doherty Earth Observatory, Columbia University (as Peter Demenocal) |
| Sheila Watt-Cloutier | ... | Herself - International Chair, Inuit Circumpolar Conference |
| Ray Anderson | ... | Himself - Founder, Interface, Inc. |
| Tim Carmichael | ... | Himself - President, Coalition for Clean Air |
| Omar Freilla | ... | Himself - Director, Green Worker Cooperatives |
| Wallace J. Nichols | ... | Himself - Senior Scientist, The Ocean Conservancy |
| Diane Wilson | ... | Herself - Author, An Unreasonable Woman |
| Andrew Weil | ... | Himself - Director, Program for Integrative Medicine, University of Arizona |
| Theo Colborn | ... | Herself - President, The Endocrine Disruption Exchange |
| Jeremy Jackson | ... | Himself - Oceanographer, Scripps Institute for Oceanography |
| Tzeporah Berman | ... | Himself - Campaign Director & Founder, Forest Ethics |
| Gloria Flora | ... | Herself - Director, Sustainable Obtainable Solutions |
| Mikhail Gorbachev | ... | Himself - Founding President, Green Cross International, 1990 Nobel Peace Prize Laureate |
| Thomas Linzey | ... | Himself - Executive Director, Community Environment Legal Defense Fund |
| Michel Gelobter | ... | Himself - President, Redefining Progress |
| Lester Brown | ... | Himself - President, Earth Policy Institute |
| Herman Daly | ... | Himself - Professor, University of Maryland, Former Senior Economist, World Bank |
| Betsy Taylor | ... | Herself - Founder, Center for the New American Dream |
| Wade Davis | ... | Himself - Explorer-in-Residence, National Geographic Society |
| Jerry Mander | ... | Himself - Director, International Forum of Globalization |
| William McDonough | ... | Himself - Architect, William McDonough & Partners (as Bill McDonough) |
| Bruce Mau | ... | Himself - Creative Director, Bruce Mau Designs |
| John Todd | ... | Himself - Ecological Designer |
| Rick Fedrizzi | ... | Himself - President & CEO, US Green Building Council |
| Greg Watson | ... | Himself - Vice President, Massachusetts Technology Collaborative |
| Leo Gerard | ... | Himself - President, United Steel Workers International Union |
| Mathew Petersen | ... | Himself - President & CEO, Global Green USA |
| Peter Warshall | ... | Himself - Ecologist, Whole Earth Catalogue |
| Andy Lipkis | ... | Himself - President & Founder, Tree People |
| rest of cast listed alphabetically: |
| David Attenborough | ... | Himself (archive footage) (uncredited) |
| George W. Bush | ... | Himself (archive footage) (uncredited) |
| Al Gore | ... | Himself (archive footage) (uncredited) |
| Arnold Schwarzenegger | ... | Himself (archive footage) (uncredited) |
| Brian Williams | ... | Himself (archive footage) (uncredited) |
company.