One hears a claim from time to time from the environ-mentally challenged individuals (of the watermelon genus), that the melting of icebergs will raise the level of the Earth's oceans. Put aside for the moment whether human beings are effectively responsible for this, and what can or should be done about this.
Just follow this simple science experiment. Put an ice cube or two in a glass. Add water to the glass until the water reaches the rim of the glass. The ice cubes will then jut above the rim of the glass. Set aside the glass for a few minutes until the ice cubes have melted down somewhat. You will notice that the glass has not overflowed its container. Go ahead and leave it and come back a half hour later when the cubes have all melted away.
Wait, that's crazy, where has the water gone? It has not evaporated away if that is what you are thinking (not enough to make a difference anyway.) The answer is simple.
Ice is less dense than water; it will take up more space than water of the same mass. IIRC, the ratio of densities of ice to water is 1/9 less. That is why ice floats on water, it cannot displace a greater mass for the same volume. It can displace a lesser mass of water though, if it lies partially out of the water. That is why a small portion of icebergs and ice cubes protrude out of their surrounding liquids.
Anyway, to get back to my initial inquiry; even if all the world's icebergs melted completely due to global warming, what do we have to worry about?