If you drop an ice cube into a glass of water the water level will rise but when the ice cube melts the water level of the glass remains constant. This is because the mass volume of a cube of ice remains contant as well regardless of its phasing from a solid to a liquid.
Okay so, I know this is probably a very naive uneducated inquiry for most of you in this forum but my question is this: If the glaciers of our arctic oceans are in fact melting then how exactly will that cause an increase in volume of our planets sea level?