The arctic is solid ice and if it melts, then the sea levels will drop. The antarctic is a continent and the ice sits on top of it. If it were to all melt, then the sea levels would probably rise. All that being said, I think the planet changes and has done so for its entire history. I believe that past civilizations had reached levels of advancement that we can't understand. There are ruins under the ocean just off virtually every landmass in the world. The oceans did rise and covered cities around the world. What does all this mean? I honestly have no idea. I just know that we don't know very much about anything in history beyond 4-5k years ago.