> Today the Earth has 148 million sq. km of land area, of which 16 million sq. km is covered by glaciers. A sea level rise of 66 meters would flood about 13 million sq. km of land outside Antarctica. Without polar ice, Antarctica and Greenland would be ice free, although about half of Antarctica would be under water. Thus, ice-free land would be 128 million sq. km compared to 132 million sq. km today.
I can't check all the calculations, but this result doesn't seem too terrible since we'd likely be able to migrate affected people in time.
The amount of migration that has completely upended political systems in the United States and Europe since 2010 or so will be a historical footnote compared to the migration we will experience due to climate change. The United States elected a professional wrestling character to the Presidency because he promised to be cruel to immigrants. Forgive my pessimism but I do not think "we will be able to migrate affected people in time" barring a major transformation of our society.
https://coast.noaa.gov/slr/