However, the southern icecap is far more massive and sits mostly on land, on Antartica - osme of it is BELOW sea level. Melting it all would cause an enormous rise in sea level - I am hazy on the exact details here, but, trust me, we don't wan't to do it! Meanwhile the continent of Antartica would rise, freed of all the icecap's weight.
If it means anything, I have a Ph.D. in Physics.