I am starting to get quite upset at the fear factor card being played by environmentalistas and their ilk who think that the polar caps melting will cause flooding and devastation across the globe. So I am going to take a second and tell you a story my dad told me as a kid.
In the Greek city of Syracuse, a couple of thousand years ago, the king was having a problem with goldsmiths pilfering his gold by substituting lead in with the gold when it was melted down. Once it was reformed, it was difficult for the king to know if he was getting ripped by the goldsmiths.
So he asked his chief scientist, Archimides to figure out a way to catch them if they did substitute something in. Archimides was befuddled with the idea until one day, while dipping himself in the tub for a bath, he noted the displacement of the water. In this bathtub the concept of density was born. Archimidis, in his excitement at solving the problem for the king, jumped out of the tub, and streaked down the streets of Syracuse screaming “Evreka!, Evreka!!” or “I’ve found it!!, I’ve found it!!”
Density is how much mass something has with respect to the volume it takes up. Regular tap water has a density of 1000 kg/m3 . (A nice round number that happens to be that way because of the beauty of the metric system). But other substances, such as gold are much higher, whereas, oil is quite a bit lower explaining is why it floats.
Let’s apply Archimides discovery of density to icebergs. (Because after all, the north polar cap is just a giant iceberg)
First let me explain to you what happens when liquid water is cooled enough to form ice. The temperature drops and as water begins to freeze, it expands. This is because the density of ice is about 920 kg/m3, and that of sea water is 1025 kg/m3.
So what does this mean? It means the ice is less dense than it used to be as water. With this density decrease, the ice begins to float, because in a way, it is lighter than sea water. The ratio of ice that is “pushed” above water is about 10% of the mass of ice. This concept is best understood if you do not think in terms of ice floating, but instead, think in terms of the ice below sealevel being lighter than the surrounding water enough to lift about 10% of it’s mass above water. The mass in this case is the top of the iceberg but could be anything, such as ohhhhh, an expedition heading to the north pole or a harp seal waiting to become a nice jacket.
If you were to put a weight equivalent to this 10% on top of an iceberg, the iceberg would sink until it’s top point was just covered by water. In this case, that density decrease WOULD displace more water and raise the sea level. But in reality there is no weight to push icebergs underwater. There is only Archimides and the math behind density. And density says that they can freeze or melt all they want. If they do it while floating in the oceans they will not affect sea level.
That’s the Officially Screwed math lesson for the day. Now if you want to amaze your friends, take a clear glass jug, fill it about 2/3rds full of cold water, and toss in as much ice as you like so long as none touches the bottom of the jug. Then mark the waterlevel and wait for the ice to melt. The ice that floats up above the waterline will have no effect on where the water level is when it melts. You should note that the water level is exactly where you marked it.
Go and amaze your lefty friends with what they will consider a parlour trick, but you can rest assured is simple science that is over 2000 years old.
