I am writing a story, in which humanity is struggling to survive and rebuild civilisation hundreds of years after a devastating war with AIs. I'd like the world to be covered in deserts, where humans can only survive inside few remaining, sheltered city-states.

Initially, I planned to make this a post-nuclear war setting, where radiation is the main threat, but I found out that nuclear weapon radiation would be gone very quickly, nor would be it be able to desertify the planet.

It seems hard to come up with even a moderately viable possibility... (I don't want to touch on the ecological options, like climate change.)

So far I came up with this: AIs mainframe was located on the Moon. Humans shot an experimental anti-matter weapon/missile at it, which consumed part of the moon and broke the rest of it into pieces. This has slightly altered Earth's orbit, causing increase in temperatures - climate is unstable with majority of the surface being deserts.

  1. Would this scenario be sufficiently believable? How much sense does it make from scientific perspective? Can I change anything to improve this concept?
  2. Would Earth maintain it's altered orbit afterwards?
  • $\begingroup$ Feels it's a lot easier to achieve the same result just in a bit of a different way. First you can connect the destruction of the AI moon to the lingering problems on earth. 1 of 2 ways. Either the AI itself changed the nature of the moon, or humans with a weapon ended up doing that. Maybe AI was creating robots and want to have a hostile place. Or humans used experimental weapons. Then once the moon ended up falling to earth it distributed those deadly effects. They ended up contaminating the water. Poisoning plants. Making most of the world toxic...etc whatever you want to fit the story. $\endgroup$
    – Seallussus
    Commented Apr 14 at 4:26

1 Answer 1



  • Getting Earth to be a hot desert without killing all multicellular life is probably impossible. (It's the oceans. You have to get rid of them - and the only way to do that is to make Earth so hot that not only do the oceans boil, but the atmosphere gets so big most of it drifts off into space.)

  • Getting your audience to suspend their disbelief and accept that Earth is a hot desert now because of (insert apocalypse here) is probably trivial. A lot of (uninformed) people already believe that Earth will end up as a hot desert (or various other equally impossible scenarios, like a a waterworld) because of climate change. Sci-fi is full of desert Earth scenarios.

  • Worldwide ice desert is a borderline plausible option. See: Snowball Earth.

  • Mars is a desert. It also doesn't have air - all the more reason to huddle together in a few sheltered city-states! Unfortunately, the lack of air may make Mad Maxing across the wasteland, shiny and chrome, much less worth witnessing.

  • The moon is definitely a desert and is quite hot on the day side. Maybe there is a space elevator on the moon with a nearby cloud of rotating space habitats (built out of moon metal which was boosted into orbit on the space elevator using moon material fusion).

Some options for hot desert settings:

  • Just suspend disbelief. Mention "the dry salt wastes where the Pacific Ocean used to be, before the bombs fell and the climate changed" and don't look back.
  • It's regional - and the apocalypse never stopped. Maybe the robots built giant rain-trapping walls around the continents and the wet coastal regions are patrolled by killer robots or infested with lethal nanites.

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