What made the climate in north Africa change from tropical to grasslands then to desert?

Answer 1

North Africa has experienced a number of climate changes, mainly due to a decrease in rainfall. There was a time (8000 BC to 6000 BC) when the Sahara -- the world’s largest hot desert and one of the driest places on earth -- attracted visitors for its rainfall, occurring due to melting ice sheets from the previous glaciation period and Indian ocean monsoons. According to Scientific America, there have even been caves found featuring animals like giraffe and crocodiles that favor Savannah conditions.

After this period, over a span of thousands of years, the Sahara became increasingly dry, wet climate flora and fauna being gradually replaced by its dry counterparts.

Desertification, a process where semi-arid areas are depleted of their water sources and biodiversity and transformed into non-productive desert, is another answer for this climate change. This is particularly occurring in the Sahel, a belt of land stretching from the Atlantic Ocean to the Red Sea. A variety of factors contribute to this detrimental process, some of which include poor land management, drought, overgrazing by domesticated animals, over-forestation, increasing human populations and irresponsible use of Natural Resources.