[quote=@NecroKnight]
[@MetalLover]

So, most of my issues would be in that case the rising sea levels?

When was 'international' trade re-established? Or rather the surviving and prospering nations decided to re-assume contact with the rest of the world? And see who was still alive?
[/quote]

Yes, most of your issues would be regarding the rising sea level. 

The re-establishment of International Trade would vary between nation to nation, with the areas that weren't as damaged in the war establishing it with other territories much quicker than others.