We can't predict how much the sea level will rise. What you do is use sea walls and dikes to prevent flooding should there be strong hurricanes. This has been done historically for well over a thousand years. The netherlands, most of the lands is below sea level, and people live there quite comfortably because they have a system of dikes. There's a proposal to build a sea wall around lower manhattan preventing the kind of thing that happened an you know, i forgot how many years ago,. en there was a hurricane that flooded lower manhattan.