What Causes Global Warming?

Carbon dioxide and other air pollution that is collecting in the atmosphere like a thickening blanket, trapping the sun's heat and causing the planet to warm up. Coal-burning power plants are the largest U.S. source of carbon dioxide pollution -- they produce 2.5 billion tons every year. Automobiles, the second largest source, create nearly 1.5 billion tons of CO2 annually.

• Melting glaciers, early snowmelt and severe droughts will cause more dramatic water shortages in the American West.

• Rising sea levels will lead to coastal flooding on the Eastern seaboard, in Florida, and in other areas, such as the Gulf of Mexico.

• Warmer sea surface temperatures will fuel more intense hurricanes in the southeastern Atlantic and Gulf coasts.

• Forests, farms and cities will face troublesome new pests and more mosquito-borne diseases.

• Disruption of habitats such as coral reefs and alpine meadows could drive many plant and animal species to extinction.