Dying deserts

The habitable world-desert looks more difficult, given the difficulty the classic SF authors have had with it. For competent authors, that is also what makes them interesting.

Frank Herbert did propose an ecology for Dune, but his efforts there were (in the end) desultory, like CS Lewis admitting that for Out Of The Silent Planet he had done only as much worldbuilding as would convince himself. Both authors’ interests lay elsewhere. George Lucas did even less work for Tatooine (I’ll get to Hoth later): on his monocosm planets, he didn’t even ask if there exist an ocean elsewhere than in the (small) communities he detailed. They may well have oceans out of view. Blame the Expanded-Universe nerds for coming up with silly answers.

For a desert world to support oxygen implies it too has seas, but the continents are arranged such that little water falls on land. Start with the assumption of a land-dominated planet. Brian Aldiss mentioned such a world offhand in Helliconia Winter – “New Earth” or “Arabia Deserta Writ Large” (on Alpha Centauri C; we expect different of Proxima’s world now).

Now, here’s the problem: we have several examples of land-dominated planet close to home, and all have ended up with no surface liquids at all. I mean, except for Titan. Where the sun is so dim the liquids are ethane.

Land-dominated worlds aren’t tectonic; habitable worlds bask in hot sunshine. Put these together, and take away the Van Allen Belt: such worlds WILL die before their time - like Mars (sketched as Malacandra or Barsoom) or, worse, Venus. Even if they’ve kept a magnetic field, the water is still going to evaporate and blow off into space some day. Visiting comets and volcanism can resupply the water, but those events will be both erratic and catastrophic. For the small oceans and their shores: vast temporary flooding and changes to ocean chemistry.

Aldiss’ Ediacaran New-Earth, with its plants and worms, is doomed as Barsoom. And Edgar Rice Burroughs did it better.

In science-fiction, we can at least invoke an alien’s terraforming effort. I would argue Kharak in Homeworld’s backstory; levees, against the encroaching desert, should count. I would propose that also for Tatooine; but Lucas’s third movie scotched that idea with the sarlacc, implicitly a native to this world.