https://www.biocarbonengineering.com/ These guys use drones to shoot tree seeds in the ground.

Also regarding terraforming a dessert, I think one of the biggest problems with is the number of water needed in the area, but I do think that this will be a really interesting part of the solution. Maybe the increase of land prices due to the decrease of arable land might make such ventures more profitable. There's a great ted talk about reversing desertification: https://www.ted.com/talks/allan_savory_how_to_green_the_worl...