Stefan Kröpelin
Civilization’s Mysterious Desert Cradle
The Sahara and civilization
“Almost everything breaks in the desert,” Kröpelin began. He showed trucks mired in sand, one vehicle blown up by a land mine, and a Unimog with an impossibly, hopelessly broken axle. (Using the attached backhoe, it hunched its way 50 miles back to civilization.)
The eastern Sahara remains one of the least explored places on Earth, and it is full of wonders. Every year for 40 years Kröpelin has made multi-month expeditions to figure out the paleoclimatological changes and human saga in the region over the last 17,000 years. There are no guides, no roads. When you find something—astonishing rock art (there are thousands of sites), an amazing geological feature—you know you’re the first human to see it in thousands of years.
A great river, 7 miles wide, 650 miles long, once flowed into the Nile from the desert. Now called Wadi Howar, its rich, still unstudied archeological sites show it used to be a thoroughfare from the deep desert. A vast spectacular plateau called the Ennedi Highlands, as big as Switzerland, has exquisite rock art detailing pastoral herds of cattle and even dress and hair styles. Mouflon (wild sheep) and crocodiles still survive there.
Most remarkable of all are the remote Ounianga Lakes, some of them kept charged with ancient deep-aquifer fresh water because of the draw of intense evaporation from a hypersaline central lake. In 1999 Kröpelin began a stratigraphic study of another lake’s sediment, eventually collecting a treasure for climate study---a 52-foot core sample which shows every season for the last 11,000 years.
For Kröpelin, many strands of evidence spell out the sequence of events in the eastern Sahara. From 17,000 to 10,500 BP (before the present), there were only a few human settlements along the Nile. But the Sahara was gradually getting wetter in the period 10,500 to 9,000 BP, and people moved up from the south. The peak of the African Humid Period, when the Sahara was green and widely occupied, was 9,000 to 7,300 years ago. Then a gradual desiccation from 7,300 to 5,500 BP drove people to the Nile, and the first farms appeared there. From 5,500 BP on, the Nile’s pharaonic civilization got going and lasted 3,000 years.
Unique artifacts such black-rimmed pots and asymmetric stone knives, once used in the far desert, turn up in the settlements that created Egypt. Kröpelin concluded: “Egypt was a gift of the Nile, but it was also a gift of the desert.”
And of climate change.
watch
primer
Anything as vast and mysterious as the Sahara Desert is bound to invite myth and legend – it’s how we make sense of things too large, elusive or forbidding to know firsthand. Stefan Kroepelin, however, has dedicated his life to firsthand knowledge of the Sahara, and has dispelled some myths along the way. He’s come to know, better than almost any outsider, the desert’s eastern portion, made up of Libya, Egypt, Chad and Sudan.
Kroepelin is a geologist and archaeologist who has studied the interplay of human settlement and the Sahara’s changing climatic characteristics over the last 10,000 years. He’s encountered a fair share of difficult conditions and frightening surprises in the desolate, harsh and sometimes lawless expanses of the Sahara. But as Nature put it,
those decades of difficult field work have paid off for Kroepelin, who has made seminal discoveries about the climatic history of the Sahara that are challenging assumptions about the tipping points the world may face in a warmer future. – Nature
The story that Kroepelin has helped piece together opens on a Saharan region vastly different from the one we know today.
10,000 years ago, the Sahara was significantly wetter than it is now, a lush savannah that supported life and hints of early civilization where sand and little else can now be found.
That little else has been the key to Kroepelin’s success, though. He and his team took core samples from the bottom of a lake in Chad and, by analysing the layers of sediment that had built up over the last few millennia – and the pollen contained therein – were able to draw the clearst picture yet of the region’s dessication and dessertification.
Previous attempts to describe this transition were similarly based on core samples, but these were taken from the Atlantic Ocean rather than the Eastern Sahara itself. Where the story told by these samples described a precipitous change, Kroepelin had already established that human settlements in the region didn’t appear to have been abandoned quite so quickly, or as he put it on Science Friday in 02008,
We were using man as a very sensitive climate indicator.
His new core sample squared with the picture of a more gradual shift and upended the previous research. The people displaced by the region’s drying out made their way east and found the water they needed at the banks of the Nile. There they developed one of the longest-lasting civilizations known to history.