Fill up a cup with water. Put an ice cube in it. Question is, when the ice cube melts, will the volume of water rise? Answer is no. A iceberg in the ocean already takes up the volume. It can melt, break off and settle in NY harbor and it wouldn’t add an inch of water to the harbor.
So the measurement is how many square miles are ice flows which are land based, their aggregated volume and if they fall into the sea, how much will the ocean rise? Sounds like a simple equation.
” their aggregated volume “
Mass