Between 9,000 and 6,000 years ago, the Sahara desert experienced wet and rainy conditions, forming a "Green Sahara". Evidence from sediments and cave paintings show rivers, lakes, and fertile land supported diverse wildlife and human civilizations. After 2,000 years, drier conditions returned and the desert formed. Computer models suggest human-driven climate change could cause future expansion of Sahara vegetation, but human activity in the region may prevent a full return to former "green" conditions.
3. PLAN
Green Sahara
How do we know
What’s happened ?
A new Green Sahara soon ?
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4. GREEN SAHARA
What ? Wet and rainy conditions in the northern
Africa
When ? 9 000 and 6 000 years ago
How ? Climate change
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Green Sahara
5. GREEN SAHARA
Water
• Rivers
• Lakes
Life
• Fertile conditions
• Animals
Humans
• Humans
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6. GREEN SAHARA
Crocodiles, elephants, giraffe, hippos, antelopes,
fish, …
Civilization used rivers : boat, raft, fishing (hook,
harpoon, line, …)
Civilization learned a lot : cooking (porridge, soup,
…), pottery
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7. HOW DO WE KNOW ?
Sediment : evidence of water
Cave painting : evidence of civilization and animals
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How Earth Made Us - Sahara
8. WHAT’S HAPPENED
After 2 thousands years, the drier conditions that
prevailed prior to the Green Sahara returned.
Desertification advanced, and the Sahara
desert formed (or re-formed). Arid conditions have
continued through to the present day.
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9. A NEW GREEN SAHARA SOON ?
Computer model simulations : an expansion of the
vegetation cover in the Sahara Desert ( human-driven
climate change leads to aggressive global
warming)
Sahara won’t actually become greener than it is
today, as the simulations do not account for the
influence of human activity in this area.
Science Daily 9
10. Thanks for listening.
Do you have any questions ?
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wendy.bintner(at)etu.emse.fr
Notes de l'éditeur
a humid phase across North Africa which peaked between 9,000 and 6,000 years ago.
elephants, giraffe, hippos, and antelope, crocodiles
Nilotic peoples
