there’s enough ancient water under the sahara to keep the desert green for 50—100 years. after that it runs out.
the saudis also had an ancient aquifer that they tapped for a couple decades to grow wheat. for awhile they were like the fourth or fifth largest wheat producer.
then the water ran out.
All the deserts of the world will be turned green. That will happen when the price of desalination drops another couple hundred dollars @acre foot to around $300@acre foot.
There are two technologies currently maturing fast that will make that happen. Fusion energy which will reduce the cost of energy to a fraction of what it is today. The second one is a technology that will extract the minerals and metals from salt water at prices that are cheap enough to make them profitable to sell. That’s more complicated but also doable.
In less than ten years this world changing technology will happen.
You don’t need fusion to desal the deserts. There already is a giant thermonuclear reactor in the sky showering the deserts with 330+ days a year of full sun. Commercial panels output 450’watts using exactly 2 sq meters of cell area Th st means in a 10 hour day we will throw out the first and last two hours of daylight at Saharan summer vs winter the yearly full sun avg is 10 hours per day. So 2.25 kwh per square meter per day. It takes 3kWh to desal a cubic meter of seawater to fresh water so each sq meter of surface area makes 0.75 of a cubic meter per day 330 days a year or more.
0.75 cubic meter is 75cm of water over a square meter of surface area. 75cm is 29.5 inches of water per day that’s equal to 29 inches of rain per day per square meter crops in a desert with high ET rates like corn or wheat are going to need 60” per season to grow. That’s two days worth of solar power per square meter flier season you can see that one sq meter of panels would support a hundred sq meters of crops this is the way no fusion needed just cheap panels set at an angle equal to latitude grow crops under the panels the shade will help with the ET loss rates plants don’t need full.blazing desert sunlight it actually too strong for them.