We're now going the other direction, rewarming the earth, and permanent ice is increasingly disappearing, as you'd expect. At some point, permanent ice will be gone. At some point before that, its loss will be inevitable. Like the passengers in this car, its end may not have come — yet — but there's no turning back.

http://digbysblog.blogspot.com/2015/06/we-have-passed-tipping-point-for.html