The way it happens is that sea level rises slowly, so slowly it's barely noticeable. Then, literally overnight, a storm causes specific sections of land to go underwater. It's very expensive, even if we plan for it. But we never do seem to plan for it adequately, do we?
CO2 emissions will go down as fossil fuels become harder to obtain and the cost of alternative energy decreases. It's inevitable to reduce CO2 emissions, because fossil fuels will simply be exhausted. All we can do is speed up that process by imposing a carbon tax. We came together to reduce CFC emissions and sulfur emissions to alleviate the ozone hold and acid rain, so why not CO2 emisisons?