Armok made a huge mistake with the ice.
The entire stone part of the cavern has filled with water from the leaking aquifer.
Many dwarves drowned. Armok is an idiot who previously got too comfortable on a frozen-all-year map...
If anyone survives they have a rough year ahead of them.
Armok should never have let all these dwarves become friends.
Friendship: A dwarf is rather more upset when his friend dies.