The Sahara Desert may be the hottest desert now, but in 15,000 years it will be green again! The reason why will surprise you

The Sahara is the world's hottest desert, and the third largest desert after Antarctica and the Arctic. It covers most of North Africa and some of it's sand dunes can reach 180 meters (590 ft) in height. People lived on the edge of the desert thousands of years ago since the last ice age, when it was a much wetter place.

In 1600 BCE the Sahara was a savannah with lush vegetation. It has become a desert as shifts in the Earth's axis created a climate change that increased temperatures and decreased precipitation, turning it into a sandy desert.

The climate of the Sahara has constantly changed from wet to dry over the last few hundred thousand years. This is due to a 41,000 year cycle in which the tilt of the earth changes between 22° and 24.5°. It is currently in its dry period, but it is expected to become green again in about 15,000 years time.

The Sahara has recently been experiencing increased rainfall and satellite images show extensive re-greening between 1982 and 2000. No one alive today will experience the complete re-greening of the desert, but the evidence shows that it will indeed happen again.

(Source)