No need. The world has LOTS of desert area that will work just fine for the purpose. A tiny fraction of the available area will do the job for the entire world.
You can't be series! You're advocating blocking huge areas of the desert floor from getting sunlight? What will happen to all the happy little desert reptiles, insects, and endangered desert microbes living in the sand? Their demise would represent an environmental catastrophy of epic proportions! How heartless of you!
Save the scorpions! Save the sandworms! Save the cactii!
Yup--quite true!
"Save the scorpions! Save the sandworms! Save the cactii!"
Hmmmm---do you have Earth confused with a place called Arrakis??