[snakeoil]

How much of the Glaciers is above water and not at water level. So much for your displacement theory.
We are skating on thin ice- Reason, your guess is as good as mine. It appently has happened millions of years ago and will probably happen again.

[RetSignman]

Two thirds is under water because of weight, as the one third melts, the glacier rises and IT will melt.
Now about the gases?