The Great Cataclysm

The Great Cacaclysm is the name given, by The Circle, to some future event that will supposedly be catastrophic, and be somehow related to, or perhaps even caused by, Fran Grenouille. 
Whatever the event is, Arvin Costlemach's wife (Claudia Horne's mother) lost her life during or because of it, and this is - apparently - something that cannot be undone. ("Circle")