Today the Sahara is among the driest places on Earth. Yet rock paintings deep in the desert show cattle, giraffes and swimmers.
The African Humid Period
From roughly 15,000 to 5,000 years ago, North Africa was much wetter than today. Scientists call this the African Humid Period. Large lakes formed, rivers flowed and grasslands supported animals and people.
What changed the climate?
Small, regular changes in Earth's orbit altered how much summer sunlight reached the Northern Hemisphere. Stronger summer heating intensified the West African monsoon and pushed rain far to the north. As the orbit slowly shifted, the rains retreated and the desert returned.
