"With additional climate change, the number of people on the move is almost certain to rise. By how many will depend on future levels of greenhouse gas emissions, socioeconomic development trajectories (especially in low and middle income countries), and, to a lesser extent, future international migration policies"
We must prepare health systems for rising numbers of people on the move Involuntary displacement of people by climate hazards generates substantial challenges for human health and health systems in all countries and regions. Over 20 million people annually are displaced by floods, extreme...
www.bmj.com
Most will be from extreme weather etc. Which is widely predicted. There will be areas that are too hot to live, but that isn't the major issue.
The seas won't boil, although there is a theoretical point where they would (they won't in reality of course)