According to projections, if we don't curb climate change, sea levels could rise by as much as 25 feet. The good news is that this won't happen for a couple of millenia. The bad news is that sea level could rise by a foot or two within the next century. Artist Nickolay Lamm shows what would happen in various major cities in a worst case scenario.
Here's South Beach in Florida if sea levels rise 5, 12 or 25 feet:
You can see more pictures here and here.
If you're nervous and you live near one of these 24 regions, you can see whether your home will survive the coming floods.