[gitrog]

https://nsidc.org/news/newsroom/20050801_floatingice.html

Salt water is denser than fresh water. The displacement of the Arctic ice is less than the displacement of the water contained in that ice when it melts. So the sea levels will rise. Though, that's not the only problem...

Think of the Arctic as exactly what it is, a giant ice cube, keeping your drink (or, you know, the world) cool. The smaller the ice cube gets, the smaller its effect on keeping your drink cool. When it's gone, your drink quickly goes to room temperature. It's highly unlikely that we can survive like we currently do without the Arctic. Sure, the ice might come back in 10 000 years or so, not particularly useful to us in the short term though, is it?

And the problem isn't that the Earth goes through natural cycles of cooling and warming, it's that our actions are accelerating the warming of the Earth, meaning we've got even less time to figure out how we as a species would survive the natural heating of the Earth.