Desertification is the process of desert-making. Naturally, it happens at a slow rate and the forests also take over the desert at the same or a similar speed. But you guessed it, the climate crisis is causing it to occur at a much faster rate. This is not good.

According to Earth Observatory in NASA (https://earthobservatory.nasa.gov/features/Desertification/desertification2.php),

"Scientists are beginning to say that desertification is a reduction in the productivity of the land that is not reversible ... land is desertified when it can no longer support the same plant growth it had in the past, and the change is permanent on a human time scale ... Drought, overgrazing, fire, and deforestation can thin out vegetation, leaving exposed soil. If the nutrient-rich top soil blows or washes away, plants may not be able to return. Overfarming or drought can change the soil so that rain no longer penetrates, and the plants lose the water they need to grow. If the changing force is lifted—drought ends or cattle are removed, for example—but the land cannot recover, it is desertified. The loss of productive land for a season or even a few years is one thing, but to lose it effectively forever is clearly far more serious."