Even now, the human deluge is beginning
The refugee migration is now greater than every since WWII. The causes appear to be many, but global warming is an ever-increasing contributor. For example, the civil war in Syria is a sizable source of refugees. There are many factors that worked to bring about the conflict, but a critical one was a multi-year drought devastating agriculture. This time a drought aggravated by global warming is a small part of the chaos, but this is just the beginning. This is just a peak at what we are going to see as population increases encounter declining resources due to global warming.
Extreme weather events of all kinds will batter the world, but the primary factors will be drought and energy resources.
In the American Southwest, as water supplies in rivers, lakes, and underground, dwindle, the land will impoverish sending inhabitants into migration to wetter places like the Northwest and the Northeast. This migration will contribute to social disorder as people compete for resources. People in the Northwest will organize to monopolize what they have, while those immigrating will find ways to either create or seize what they need. Conflict will be inevitable.