I appreciate your concern, Wolfgang, but I am aware of the physics of the issue. It is incorrect to think of the northern polar cap as simply a big floating ice cube -- and therefore not a threat -- when sea level changes are compounded by many other issues. Nor is ice just "ice."
The sea level can rise for multiple reasons, among them: 1) Antarctic ice sheet melt 2) Greenland ice sheet melt 3) warmer water temperatures cause water to expand, also called thermal expansion 4) glacial melt
Because of new information about how humidity and temperature affect polar precipitation, it is now believed that the sea level will not rise as dramatically as previously thought, but the sea level has already raised measurably. (Scientists seem to go back and forth on this issue of "how much"; I doubt if this is the final word.)
However, as mentioned earlier, current changes and climatic changes are also important issues, as are erosion problems and inundation of low-lying areas. Coastlines will be dramatically revised, not just because the sea level goes up, but because of the way the ocean interacts with coastline. But when you are talking about a projected sea level rise of 5-11 feet, most of the continents are not greatly in danger, but many islands are. At most risk are low-lying islands, which started this discussion.