About 1/3rd of the raid-fed food we consume is produced - yep you guessed it, close to those same bodies of water. So we'd loose food-producing capacity. Most of our internationally-traded goods are transported via ships; we'd have to replace many/all our ports. Same holds true for a lot of our other resources.
Sure. But if the coastline moves, then after sufficient time everything associated with that will move too. Rainy land is near the sea because it's near the sea, shipping ports are near the sea because they're near the sea.
Tho I'm not considering farmland here. Sure that might be a serious problem. My point was about populations having to move, which I still think is quite acceptable based on my previous reasoning. Mainly that just about the entire world's population has already had to move over the last 100 years just to get away from each other! People are still building new houses when they're too numerous to live in their parents' house, despite the huge expense.
