It is harder for people to migrate today. But these changes occur over centuries. We don't even know if humans will be around in a few centuries; and if we are, things will be so drastically different in every way that I think we will have other things to worry about than whether our building is too close to shore. And cities will simply move inland, gradually.
That said, I support initiatives to reduce CO2 and methane and renewable/circular methods. It just makes sense.
I am most concerned with ocean acidification, which is mostly a result of pollution, but climate change has some impact on that.
I feel that over-population is the root problem. If the Earth only had a billion people, we would be worried about a returning ice age instead. Over-population also leads to high rent in cities, oceanic pollution, and lots of other problems.