Coal generates carbon dioxide when combusted, which is causing the world to warm. In Georgia, a state that gets over 60 percent of its electricity from coal, some coastal residents are connecting the dots between coal and changes in the local ecology and economy attributed to global warming.
Congress helped bolster the corn ethanol business in Iowa by mandating the Renewable Fuel Standard in 2005. But scientists are concerned about the unexpected consequences of putting more of Iowa's land into corn production.
Montana's recreational fishing and agricultural industries depend on cool waters flowing from melting snow high in the mountains throughout the summer. But across Montana, rising temperatures are causing a series of changes.