been unfairly characterized as a pollutant. FRED PALMER: In the past, we've had these great struggles over pollution in the United States. Sulfur dioxide is a pollutant. Nox (sic) is a pollutant. Carbon dioxide is a benign gas required for life on Earth. It is not a pollutant. It is not regulated. There are no state laws dealing with CO2. There are no congressional laws that give an agency the right to regulate based on CO2. NARRATOR: Far from being a pollutant, the coal industry argues, CO2 is a powerful plant fertilizer, so producing more of it will green rather than pollute the planet. Its video The Greening of Planet Earth maintains that industrial CO2 will fertilize the Earth, and the enhanced forests will eventually soak up the excess greenhouse gas. ANNOUNCER: ["The Greening of Planet Earth"] Grasses will grow where none grow now, and great tracks of barren land will be reclaimed. NARRATOR: It argues that horticulturists pump CO2 into their greenhouses - time times current atmospheric levels - to make the flowers and vegetables grow faster. And indeed, the plants thrive. The industry believes that characterizing CO2 as a fertilizer rather than a pollutant turns the controversy on its head. FRED SINGER: The only thing we are concerned about is carbon dioxide levels becoming too low because if carbon dioxide levels were to fall below, let's say, one half of the present level, as they almost did during the last ice age- if they were to fall below