[hodgesrm]

Glaciers work differently from ice on a pond. They have a 'budget' which is determined by the rate at which snow accumulates on the top and the rate at which melting occurs lower down. When glaciers are stable they have net accumulation above that turns to ice, flows downward, and melts at the snout.

Once the temperature reaches a point where net accumulation no longer occurs anywhere on the glacier it quickly disappears.