And it's terrifying (or should be) to even those who are only self interested. Displacement of millions means mass migration and destabilization of larger parts of the world. The climate change and warming that cause it mean crop failures, novel diseases, and weather changes that will have the potential of affecting everyone.

For a simple example, it's likely that literally the entire population of the Republic of the Marshall Islands will have to relocate in the next few decades: https://www.nationalgeographic.com/environment/2018/11/risin...

Yes, that is bad. How bad though? To be both objective and realistic you would need to break that down as a cost increase, per capita, in portion to percentage increase of annual cost of living. There are real numbers to these things, and I suspect they are large, but I really don’t know. Objectively speaking until such numbers are simulated we are all just making things up and that is most depressing of all.

My bet is on war, sadly.