Florida — especially South Florida — is very flat and very low, and in places like Miami Beach and Key West, buildings are just 3 feet above sea level. Scientists now say there may be a 3-foot rise in the world's oceans by the end of the century.
Since the 1930s, Louisiana has lost roughly as much land as makes up the state of Delaware.
"If you put the state of Delaware between New Orleans and the ocean, we wouldn't need any levees at all," says John Barry, vice president of the Southeast Louisiana Flood Protection Authority-East. "There is this large buffer of land that has disappeared, and that buffer makes New Orleans much more vulnerable to hurricanes."