Sal "I suspect on this time scale the people would have just moved away from the rising seas and in a single generation would not have noticed them moving at all. We may have lost some nice cave paintings but I doubt there is an Atlantis awaiting discovery."
Mass migration, even today is not a walk in the park. 25% or possible more of Bangladesh may be lost by 2100. Will neighboring countries welcome all the refugees with open arms? Countless refugee camps now and in past years demonstrate the difficulty of relocation. And with temperature, climate patterns and sea level changes, massive changes presumably occurred to flora and fauna significantly disrupting the economic foundations and social fabric of migrating societies. And cultures advance in many directions. An advanced culture might look little like the high tech image portrayed by Atlantas fans. We have lost massive amounts of knowledge of past cultures and civilizations (Greek, Egyptian for example) that at least remain intact geographically.