The Sahara Desert is a lot bigger now than it was in the past. So, when plants die, then the ground may dry out. Land becomes desert mostly when there is less and less rain which means less plants, trees which then means less soil, fertilizer, compost. Long story short, slowly over time, the ground becomes harder and harder for life to grow on. So, what we need is enough rain. And rain come mostly because of evaporation. Less clouds means less rain which then means less green earth.
What you said about my Facebook group, I agree. Thank you.