Meh, I doubt it will end in ice.It's that poem that appears in Twilight D8
But other than that, it's a pretty cool poem~
I say it'll end in ice :3
This is because, global warming will end up causing an ice age (it always has in the past, it doesn't matter if man or nature is causing it.) And for the world to end in ice there would have to be another snowball earth event which wont happen because every billion years the sun heats up, and in about two billion years the habitable zone will be farther back then it is today and the oceans will evaporate. Note: I am not talking about the Red Giant.
So technically, the Earth is already set up to end in fire.