Have you considered that as the poles warm up enough to sustain plant life the equatorial regions would become searing deserts?
The temperate zone broadens in a warmer earth scenario. Again, the gain exponentially outweighs the losses. It’s been happening to us for well over 10,000 years now, so why all of a sudden do people have a problem with migration away from the coastlines? You do realize there are cities all over the world that are under water from rising oceans. This isn’t new. What is new is extremists saying it is new.
What extremists are saying is that it has taken over 20,000 years for the Earth to warm 4 degrees C but only 100 years to raise 1 degree C. That exponential warming trend is happening too quickly for our societies to adapt.
Yeah I know that it always will happen but it doesn't stop the thousands of deaths each year of people attempting to reach new places to start new lives by circumventing the legal routes. And they do this because they either will not succeed using the legal routes or the process is prohibitively lengthy and expensive.