When ice ages reseeded in the past, people moved north to populate what is now Europe. When ice ages returned people moved back south.
I doubt such simple solutions would occur to people today. A receding ice age is like global warming. So move north.
If sea levels rise, move inland and/or to higher elevations.
Where is the line drawn, that we are incapable of common sense adaptations, such as those made by our ancestors?
I have some 1st-3rd cousins in British Columbia and Yukon territory. Strikingly beautiful places.
Bring it on. The adventurous like my family have been will move, leaving behind the risk-averse to die slow deaths.
If it gets warmer, another alternative to moving north, is moving to higher elevations. The state with the highest mean elevation is Colorado. We ought to be safe there, for another few hundred million years.
Goodbye NYC, Lost Angeles, Houston, Chicago, Miami, Seattle, Portland, DC, and hello Flagstaff at 7400 ft. elevation.