How many people will migrate due to rising sea levels? Our best guesses aren't good enough.
... some of the latest estimates suggest that as many as 630 million people may live on land below projected annual flood levels for the end of the century.
by Sonja Ayeb-Karlsson, Celia McMichael, Ilan Kelman and Shouro Dasgupta
https://phys.org/news/2020-09-people-migrate-due-sea-good.html
Paper