How big a problem is that over a multi-decade time horizon?

There is a pretty big variation in average temperatures by country [0]. Somehow People everywhere from Thailand to Greenland manage to find food. All else failing it is a possibility to trade for calories. Let alone technology improvements that might save the day by accident.

I mean, it might make places uninhabitable over the course of a few generations, but things that change so slowly are't actually much of a threat on an individual level. Worst of the worst cases people can move or not have children - the statistics suggest that is an acceptable option to a lot of people.

[0] https://en.wikipedia.org/wiki/List_of_countries_by_average_y...