Mayor Michael Bloomberg outlined a 19.5-billion-dollar plan to defend New York Cityagainst rising seas. His proposal called for the construction of levees, local storm- surge barriers, sand dunes, and more than other measures. It went far beyond anything planned by any other U.S. city. But the mayor dismissed the idea of aharbor barrier is neither practical nor affordable, Bloomberg said. The plan notesthat since a barrier would remain open most of the time, it would not protect the city from inch-by-inch creep of sea-level rise.