That didn’t make sense to me either.
Except of course at Tahiti.
I think what they are talking about is a catastrophic melt. Happening very quickly it would seem the water levels nearer the poles would raise faster than the levels closer to the equator. Something that would happen as white hot Venus comes cruising by on it's way to become planet number 2.
Which explains what happened to Atlantis. 2 giant waves of water, one from the South, one from the North meet at Atlantis. The enormous upthrust of water submerges the huge power crystal and it goes nova. When the water recedes, levels out, Atlantis is gone.