I’m donating this drawing to the Anime Boston charity auction for the National MS Society. The convention is March 31-April 2, and the auction is on April 2. Mike and I also signed some cool stuff you can bid on too: a chibi Aang figure; a Korra poster book; and a plush Appa. I’ll post about it again when it’s closer to the event.
Because he never was frozen. Not really. He and Appa were encased in what I suppose you would have to call spirit energy.
You can see the glowing avatar energy pushing the water away from Aang. And the ice forms around that. They were encased in ice, as in a container, but they weren’t themselves frozen.
It’s the bursting of that container which releases the energy that was keeping them in a sort of stasis. That release of avatar spirit energy is the light that Zuko sees shooting into the sky. And with the energy gone there remains (most of) a hollow sphere where it used to be.
Basically Aang and Appa survive being frozen by not being frozen.