Desert farming is possible, there have been several desert greenhouse examples, some stuffed away, one bought by Goldman Sachs and actually in use in Australia. As long as you have sun and water you can grow crops. The challenge is of course that he economy will maximize fossil fuel use of any design (if it starts to actually build them), so you get expensive glass/aluminum digitally irrigated RO water desalinating etc. etc. nonsense.
For a while now I envisioned this kind of solution to keep crops cool in hot regions. The drawing above gives an impression. You basically grow crops underground, and allow light to enter the vertical trenches but you also reflect part of the light back. This can be done with bariumsulfide or calcium panels which reflect IR and UV as well as visible light. In the pits you can grow both crops and material to use to make this work like bamboo.
Of course you can also set up bamboo poles and do it above ground, but then you are more vulnerable to storms and other calamities. If you find a self sustaining way to do the pit thing you can expand it over large areas. The trick is to use zero fossil input, only input that is generated by it or can be made with whatever the system yields.
What do you think?