Like climate change seems really easy to solve if we just plant a bunch of jojoba bushes in the Mojave desert.
Also it’s the easiest thing to get the billionaires on board. Argue we are learning how to terraform Mars and suddenly Bezos and Musks’s meats would be spinning.
Here's a documentary on a (successful) Chinese project to Re-green the Loess plateau. I'd like to point out that this was a restoration program meant to return life to a previously exhausted and desertified land, not an encroachment into pristine and stable desert ecology. Which, as @DeathToBritain mentioned, is no bueno.