Originally Posted by TteFAboB

80 years is about the time the effects of Global Warming will start being felt (or two decades short of that). Warfare will take place between those who wish to remain alive and those who wish the populational level to be reduced to a level that can be sustained by the diminishing food output.

First they will come for the old, sick and infant. The old are a burden on the system. So are the sick. And the infants are a burden waiting to happen. Reproduction is prohibited. Then there'll be a triage done by skill, age, health, etc. where the worst scorers will face execution. The pile of bodies will be a great temporary alternative to other food sources.

Armies will fight with Laser tanks, guided-munition rifles, flying saucers and paralyzing focused sound-wave emitters. Militias will use today's arsenal. Once WW5 is over, the world will end and Earth will become the 2nd Mars. The "damned", as they call themselves, will be a small bunch of remanining survivors who will go back to the caves and shut the doors close to live in the underground where they can maintain a breathable atmosphere with the machines they take with them (fusion reactors, tunnel-digging machines, etc) and grow enough fungus to sustain themselves for a few centuries untill they get an epidemic and perish. Untill then, down there they will fight with stones and melee weapons made of metal junk.