The earth is a system of many systems, individual systems within it can collapse and desertification is one of the ways it happens. Runaway collapse of smaller systems can lead to primary system collapse.
The Sahara is teeming with life compared to Mars, but we also know it once hosted significantly more life before it was a desert. That old system collapsed.
The Sahara is teeming with life compared to Mars, but we also know it once hosted significantly more life before it was a desert. That old system collapsed.