if you go by scenario of major melting and then flooding at the same time if a nation really needed to move there they could biuld stuff rather quickly it all relative how badly a nation going underwater would need to move
Therefor some super-carriers are needed - swiming cities with developing possibilities like cities in 2020. Special Command-Officers for the supercarrier to control and fortify bunkers and other buildings.
Terra-Forming units and Water as an extra-resource.
I don't know I guess the U.N repeals the law since people need a place to stay since when islands sunk because of global warming they caused a global refugee crisis and since Antarctica is warm and can be settled they can go to Antarctica or this could be another reason: most native species in Antarctica are extinct because of global warming so the U.N repeals the law since the entire point was to protect Antarctica's animals.
There is an international law where Antarctica should not be settled by any country or something - Forgot what it was. So instead, maybe an event where the world is flooded or something similar and the only land left is Antarctica? Then all nations battle it out? Hmm... Will be honest though, sounds similar to Call of War's event, but that event mission is to kill Nazi's. This one could be a battle royale one or maybe people here can think of something?!
A few other people suggested that before you I believe
