Energy Killers justify these demands by pointing to computer models that conjure up disaster scenarios in which rising carbon dioxide causes icy habitats to melt 50-100 years from now, driving polar bears to extinction. However, hundreds of climate scientists emphasize that these models can’t forecast accurately even one year in advance, much less 50. They say there is no evidence that Earth’s moderate warming of the past century will turn into a disaster, or that CO2 is the primary cause of climate change.