the answer is simple,
As MAster Willmore has thoerized, Antartica is a separate continent.
People live year round there, on the Antarctica pennisula, I think they would know of a giant ice wall.
Whats makes more sense is the barrier (really just a metaphor) is much farther beyond.
It is the point in which our spherical sun no longer shines. What lays beyond is unknown,
and it could be endless... Much exploration is to be had to confirm, but i know very soon it will.