To me, this song means either one of these two things:
Global warming is going to kill the world and people wait for someone to change everything at the last minute like a miracle, but that doesn't happen. The angels with "arms of purest white" represent the ice that was once there. And "The sun that gave us life yesterday is now the sun that takes our lives away" is talking about how everything is beyond control.
OR
The apocalypse, which could better explain the part with heaven and angels.
To me, this song means either one of these two things:
OR