Explorer and environmentalist Jean-Michel Cousteau talks about threats to the world's coastlines, focusing on the disproportionate percentage of population that lives in coastal areas.
Scientist and climate change expert Michael Oppenheimer talks about the Clean Air Act of 1970, which he says mandated a slew of controls on automobiles, smokestacks and other sources of air pollution.
Former Sierra Club president David Brower talks about the value of critical resources, including trees, soil, water and rapidly disappearing species.
Former Sierra Club president David Brower talks about the depletion of Earth's resources, noting that, over the past fifty years, the United States has used up more resources than the rest of the world throughout all of history.