Why do ice cubes stick together in the freezer?

Answer 1

Answering the question and the question in the details below:

Ice cubes stick together because the surface of ice is liquid-like and when the ice cubes touch, the surfaces freeze together. For more background, please view the answer to "Why is ice slippery?"

The following answer gives some scientific details pertaining to ice:

Water freezes at 0 degrees celsius, but the ice that comes out of your freezer is much colder.

From the moment you put ice into water, the water gets colder and the ice gets warmer until there is one uniform temperature and all ice has turned to water. You can imagine how if the ice were cold enough, it could freeze all the water.

Two cubes of ice at say -10C would easily freeze a thin layer of cold water surrounding them before they get down to the temperature at which they begin to melt.

BUT I have noticed that often cubes that are half-melted will still stick together. How can this be? If it has been shrinking, the outer layer should be in the process of melting and therefore not cold enough to freeze its surroundings. I do not know the explanation for this. Perhaps I wasn't watching closely enough. Maybe they froze together when they were larger and for some reason the connections don't melt as fast as the other parts of the ice. More experimentation needed.

Answer 2

When two cubes make contact, there is a very thin film of water between them. Because the film is between the cubes, it cannot draw heat from the rest of the liquid, so the temperature of the film quickly drops below freezing, itself becoming ice and so fuses the cubes together. The colder the cubes, the quicker this happens.

Answer 3

The water touches the ice cubes in a thin layer and it itslef freezes thus acting as a glue.