Question

How often does it switch between desert and grassland terrain in Sahara?

Answer 1

Sahara desert is the world's largest low latitude hot desert, it is covering approximately 3.6 million square miles. On the west is the Atlantic Ocean, on the east is the Red Sea, the Mediterranean Sea is on the north, and the Sahel Savannah is on the south.

The Nile and the Niger are its two main rivers otherwise the presence of water is scarce. There are 20 seasonal lakes and huge aquifers are present in the desert. The desert receives from zero to about 3 inches of rain per year, and certain regions do not receive rain for many years. With time the Sahara desert has expanded considerably.

It has alternated between grassland and desert and the studies show that the Sahara desert was grassland some 6000 years ago and had plenty of rainfall. Due to earth rotation around the sun and on its axis has changed the location of the North African monsoon and since a grassland has changed into a desert.

That means it would take around 6000 years for the Sahara desert to change into grassland.