This is a thought-provoking, well-balanced presentation of the debate on global warming. People who hold the view that global warming is a crisis, point to temperature changes in the ocean, raised CO2 levels, and other evidence that directly ties global warming to human industrialization. Critics of this argument point to a natural, cyclical interglacial period occurring, arguing the influence of the earth's orbit and solar output fluctuations. Who is right? Scientists, world leaders, and political leaders weigh in.