New day, same bad Global Climate Change hysteria.
Yeah, rising waters usually do lead to mass migration. Whether its catastrophic or not depends on how its deal with. That's why the ability to adapt has been crucial for species survival with Darwin's Theory of Evolution.
Ocean levels could rise; Ocean levels could fall - they have before. 12,000 years ago, where I am sitting was covered by the Laurentide Ice Sheet. Now it's just another sucky overcast New England Spring day (damned East/Northeast wind).
It's not a matter of IF things will change, it's a matter of WHEN and HOW. Change is the only constant in life. Keep that Doomsday shelter well stocked so you can sleep at night.