Survival sites should be selected for their ability to link to other land areas that will be above the water line as well, so that technologies and skills can be shared among the survivors. Survivors thus will find visiting each other possible rather than impossible in a new world without maps and certainly without guidelines for boats setting out on what will seem to be an endless sea. Going on the assumption that the poles have always been, essentially, where they are found today, humans have extracted core samples which they assume will be a frozen record of climatic changes back through the eons - a dust layer here, bits of vegetation there, a higher carbon dioxide level here, and on through any number of variables. However, unlike the rings in a tree, which show its age, layers of ice do not show what is absent. The tree trunk is viewed as a whole, reflecting the life of a tree, but polar ice reflects only that portion of its life that has not melted away.
Many shifts are slight, thus causing partial melting or melting on only one side.
Thus, for the existing poles, there are places where the debris and gasses caught in the ice tell a long tale.