Quote Originally Posted by Iscah View Post
Lives aren't being sacrificed in the dark future, they've been killed by the Black Rose. It's explained when Urianger describes his "vision" (ie. relaying the Exarch's account of history from what is still our future, but his past) in 'Unto the Truth' - the "passive polarity" aspect of the gas reacted with the influx of passive-aspected aether from the First, driving it to spread far beyond its initial use on the battlefield. Vast numbers of the population die, the ground is poisoned, and the survivors go to war over what little remains.

We don't know if the Ascians can "sacrifice" what's already dead, but I would assume not.
We also don't know *how* the Ascians sacrifice to Zodiark, we're only given glimpses of a few Amaurotians vanishing while in line at the DMV. It's very possible Zodiark doesn't care how the sacrifice perishes, just so long as their Aether goes to him - as that is what all Primals require, Aether. It should also be noted that the umbral polarity of the gas may very well just be turning the land to an inactive state, similar to that of the Empty, but not quite so extreme.