His films have taken him from the challenging first year experiences of Los Angeles public school teachers to the on-stage crescendos of the rock legends U2. Best known for the blockbuster climate-change documentary An Inconvenient Truth, Guggenheim levels an idealist’s gaze and an unwavering curiosity on often the most gray of ethical and political quandaries. And he does so with true affection for his subjects. It seems he simply does not know how to make a documentary on someone he doesn’t love.