Could the Sahara have once been green? Could the world’s largest hot desert was once an oasis of life, a paradise in North Africa?
When you picture the African Sahara in your mind, what comes to mind is a great expanse of sand dunes and no sign of water. Can we imagine the Great Sahara Desert as Green Sahara? Seems nearly impossible.
Yet, what is unimaginable to people’s minds is true to nature’s creation. About 9000-10000 years ago, the Sahara Desert was a green oasis with grasses, trees and wildlife. From the scientific and even archaeological evidence, there is much that shows this was once the case.
Archaeological evidence of Green Sahara
In the mid-1800s, a German explorer Heinrich Barth became the first European to discover the now-famous rock paintings of the Sahara desert. The mere presence of rock paintings, an early sign of human settlement of the prehistoric era, indicates that not only was the Sahara green, but it hosted a sizable human population of the time. The rock paintings that were discovered over the course of time include depictions of animals like giraffes, crocodiles, and hippos.
These rock engravings show that the Saharan landscape had trees, lakes and waterbodies which supported wildlife. The rock carvings and paintings are found in the North African countries of Libya, Algeria, Morocco and parts of Egypt. These paintings and carvings were made by the Neolithic man, the population of primitive man that existed till the beginning of the classical era.
On the floor of the caves with rock paintings, explorers also found smooth crevices that were used as mortar to produce flour from seeds. All these observations show us that Sahara was once fertile, and people who lived here engaged in hunting, gathering and probably agriculture.
There are even rock paintings of animals like cows and goats that date back to millennia ago. These paintings could have been made by nomadic groups or people inhabiting the Sahara during its Green Sahara period.
Archaeologists have also found some ancient tombs. The tombs are signs that there has been significant human activity in the Sahara Desert, and people might have settled here. The presence of ancient river beds, which have now dried up, also stands as proof of vegetation and civilization in the now deserted area of the Sahara.
Even today, some of the ancient river beds fill up during the short rainy season, but the vegetation is scanty. In the dried river beds, nomadic people and pastoral communities dig up wells to access the water under the sand. However, the well has to be very deep to access fresh water from the ground. The primitive aurochs lived in the area around this time.
Geological historians believe that between the past 11000 to 5000 years ago, the Sahara area transformed into a green oasis as rainfall in the area increased. The rainfall filled up the arid caverns of the region to create freshwater lakes.
Around the lakes and rivers, green vegetation took root. Just like the present desert, the green Sahara area was also huge. The Green Sahara area was spread over 9 million square kilometers (3.5 million square miles) of earth. As vegetation grew, animals like antelopes, giraffes, hippos and even the mighty elephant made Green Sahara their home.
Today it is almost impossible to imagine the Sahara Desert as a green forested land. However, when we look at the geographical history of the Sahara, it is clear that the Saharan landscape has experienced alternative bouts of humidity and aridity.
These fluctuations in its climate have come from slight changes in the tilted axis of the earth. The Saharan landscape experiences the African Humid Period from time to time as the climate fluctuates.
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During the African Humid Period, Sahara received increased rainfall for years, which converted into a landscape of greenery. The increased moisture and rain during the African Humid Period transformed the Sahara landscape into a shrub and grass-covered area. Animals and humans then inhabited the Green Sahara area for a long time. The humans who lived also practiced domestication of animals like cattle and buffaloes.
Evidence from the Geology
The pattern of turning into a green Sahara from the deserted area of North Africa exists because of a slight wobble in orbit and the earth’s axial rotation. The wobble places the Northern Hemisphere closer to the sun in summer every 23000 years. This accelerated the West African Monsoon and brought rainfall as well as greenery to the area.
Researchers suggest from their studies that the solar radiation received by the Northern Hemisphere was 7 percent higher than the radiation received at present. As solar radiation exposure increased, the rainfall received by the area also increased by at least 17 to 50 percent. Since there was an exponential increase in rainfall, it is unsurprising that the Sahara Desert has a pattern of turning into a green Sahara.
While this pattern of alternating between the desert and green reserve should repeat for thousands of years, the most recent transformation of the Green Sahara into the Sahara desert was over a period of 200 years. Between the last 8000 to 4500 years, the transition of the Sahara from humid to extremely dry land was rapid. Apart from orbital precession, human activity was also a factor in the desertification of the Sahara.
In Green Sahara, the activity of Pastoralists grew to such an extent that the shrubs and grasses no longer regenerated. As large groups of animals grazed through the green Sahara, it turned into a scrubland and then a massive desert. Overgrazing and loss of plants led to a loss of moisture in the environment which reduced rainfall over time. Lack of rainfall turned Green Sahara into a desert. Without Human activity, Green Sahara would still turn into the Sahara Desert but not at a quick pace.
Today, we see the Great Sahara Desert in front of our eyes, but researchers suggest the phenomenon of Green Sahara could return 10000 years from now: who knows what climate change will bring.
Top Image: The Sahara desert was once a green paradise, much like the savannah such as this park in Tanzania. Source: ProfessorX / Public Domain.
By Bipin Dimri
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