Ice

[mako_amok]

Why do ice cubes eventually evaporate in a closed freezer?

[Reeder]

It's been done (http://boards.straightdope.com/sdmb/showthread.php?threadid=99277)

[tronvillain]

I would assume that it's because at the temperatures commonly found in freezers water molecules can still have enough energy to make it into the vapour phase.