Heat waves. Catastrophic storms. Migrating viruses. All are potentially deadly effects of global warming. Over the past 100 years, the mass consumption of fossil fuels has contributed to global warming--an issue that promises to do far greater damage if we continue to ignore it. Executive produced by environmental activist Laurie David, this cautionary film offers a guide to the impact of global warming on the U.S.--and the measures that can be taken to reduce this threat. (TVG) (NA)