Originally Posted by Roger Ramjets
This applies to freshwater ice, but sea ice is salty (as opposed to ice shelves or the floating parts of glaciers). Salt is extruded as sea ice ages so old sea ice is more like freshwater ice, but most of the old sea ice is long gone. Even in the worst case, if all sea ice were fresh, and it all melted the impact on sea level would be about the same as a single years worth of melting in Greenland.
Originally Posted by arthwollipot
Yes and no. While ice shelves do break up and regrow periodically under normal climate conditions, global warming means that far more is being lost than is regrown. All the major ice shelves in the artic are gone, and this is just the latest example in the Antarctic.