The president of the Sierra Club steps up to the lectern. "Hey," he greets the audience of 300 environmental leaders at a University of Oregon conference. He doffs his jacket, grins and launches into a children's song: "If you're happy and you know it, clap your hands! If you're happy and you know it, clap your hands!" The lawyers, scientists, activists and students in the auditorium, after a moment of bewilderment, burst into rhythmic applause.
Adam Werbach can be excused for a certain zany iconoclasm. After all, he is only 24--the youngest person to head the nation's largest environmental organization in...