Leonardo DiCaprio
Kenny Ausubel
Thom Hartmann
Wangari Maathai
Sandra Postel
Paul Stamets
David Orr
Stephen Hawking
Oren Lyons
Andrew C. Revkin

Leonardo DiCaprio as Narrator
Kenny Ausubel as Himself
Thom Hartmann as Himself
Wangari Maathai as Herself
Sandra Postel as Herself
Paul Stamets as Himself
David Orr as Himself
Stephen Hawking as Himself
Oren Lyons as Himself
Andrew C. Revkin as Himself (as Andy Revkin)
Sylvia Earle Ph.D. as Herself (as Sylvia Earle)
Paul Hawken as Himself
Janine Benyus as Herself
Stuart Pimm as Himself
Paolo Soleri as Himself