To get the precipitation for a continental ice sheet the Arctic has to warm up.
Already happened. Most of the honest data supporting "global warming" (as opposed to data manipulated in various ways to introduce post-hoc the purported warming trend) was actually data proving arctic warming. The whole time they've been pushing this hysteria the cooling trend in continental Antarctica stood as a falsification of their theory and was ignored. It is actually possible that arctic warming is anthropogenic, caused not by CO2, but by soot from Russian and Chinese coal-fired power plants decreasing the albedo of the arctic ice pack. (They, unlike the US and Western Europe don't have an analogue of the Clean Air Act.)
Sea floor volcanoes heat the water. It drops as snow on the land and stays there.