Link Melting of sea ice Sea level rise

Physical phenomenon

When sea ice floats, it is subjected to two forces

• Gravity, equal to the weight of the ice block (Figure 1) :
• Archimedes' thrust, equal to the weight of the volume of water displaced by the ice block (Figure 2).

Since the ice cube is in equilibrium, the two forces compensate each other. The weight of the ice cube is therefore equal to the weight of the volume of water displaced. The same weight means the same amount of matter. Therefore, once melted, it will occupy exactly the volume that was below its waterline before it melted. It will therefore not contribute to raising the water level (Figure 3).

This works for an ice cube, but it also works for an ice pack that is nothing more than a large ice cube. This demonstration only works if the ice is not supported by something solid.

Limits

A seasoned participant might point out that this only works if the water in the ice pack and the water in which it floats have the same density. As the pack ice is fresh water and not what it floats in, there can be a slight change in the water level, but it is very negligible.

Popularisation

Trivia

As this reasoning only works when the ice cubes do not touch the bottom, and in Whisky, they touch the bottom, one should not translate Ricard by Whisky. A good way to export French culture!