By the end of the century it’ll be a full-blown agricultural collapse. It’s easy to forget that our entire civilization is only possible because of a stable, temperate climate that allows us to grow enough food to sustain billions. Take that away and it goes right back to how it was pre ice age, with only a few million humans at most, living a pastoral nomadic hunter-gatherer lifestyle. Only this time there won’t be a cornucopia of megafauna to hunt.