The Green Sahara: A Crucial Factor in Ancient Human Migration
Research explains that the Sahara Desert was once a green savannah during a period called the Green Sahara or North African Humid Period, approximately 6,000-11,000 years ago. Scientists have identified over 230 instances of greening occurring every 21,000 years over the past eight million years. Changes in Earth's orbital precession, which affects the planet's proximity to the sun, caused warmer summers in the Northern Hemisphere, intensifying the West African Monsoon system and shifting the African rainbelt northwards. This increased Saharan rainfall, leading to the spread of savannah and wooded grassland across the desert. Understanding the past climate sensitivity of the Sahara is crucial for comprehending the implications of present-day climate change.
