The antarctic ice cap is mostly on land. As it melts, the water will just add to the oceans, not displacing ice.
If global warming continues, the sea level rise will be more than noticeable. It will be a huge problem.
So far as all the careful scientific studies can tell, global
warming will not only continue but get very serious unless we quickly
reduce the level of greenhouse gases we dump into the air whenever we
burn fossil fuels.
The other effect we mention elsewhere on this site is that as the
oceans warm everywhere on earth, not just at the poles, the water in
them expands. This is the main contribution to the expected rise in
ocean levels, and it is a big deal for people who live near the coast
(as a large fraction of the world's population does).
Everyone's affected by the warming trend, though -- climate change
is expected to change temperature and rainfall patterns, upsetting
delicately balanced ecosystems far from the ocean shores.
(published on 10/22/2007)