Moreover, six feet of sea level rise isn't going to happen instantaneously. It will take decades. Property will slowly be lost, but people will just move inland (or move away). And a key question is, whose property goes underwater? If it's wealthy people on the beachfront, they can afford the loss. If it's poor people, that's something else. We saw that in New Orleans, where the worst Katrina flooding happened in the poorest neighborhoods.
This also excludes the idea of simply building seawalls to protect low-lying areas. I mean, that's half of Holland, so it works. Making major social decisions on a distaste for the concept of global warming is foolish, though. Governments should operate pessimistically when it comes to threats to the land and people they govern. It should be assuming it will happen, on the worst-case side, not denying the threat because we don't like to think about it. Think that way, you might as well disband the fire department too. It's expensive and your house probably won't burn down.