[(E)]

Another idea
The ice age is a result of global warming. One or all of the temperature regulating ocean currents went out of whack. Now the arctic is a lot colder but somewhere else is a lot warmer as a result. Maybe a melting Antarctic (ice age and ocean levels rising), Amazonian desert, middle east monsoons or a burnt to a crisp Austrailia.

As for other ideas
The technology of the world is on the cusp of creating some post scarcity developments. Corporations of course dont want this to happen.

The formation of the NAU involved a long and drawn out "shadow war", now there are many enhanced veterans from all the sides involved, many of whom are still carrying an axe to grind.