The desertification of the Sahara, which began 10,000 years ago, may have been at least partially caused by humans, says a new report by scientists at Seoul National University.
Most studies suggest the formation of the Sahara Desert, the world’s largest hot desert, was brought about by changes in regional vegetation patterns and a shift in Earth’s orbit.
The Sahara Desert was once green and wet, and even covered with glaciers.
The massive Desert was once teeming with life, until some 6,000 years ago, when rains ended and the desert became as it is today.
The exact cause of the meteorological shift has been a subject of much study in recent years, as earth scientists believe it could teach us much more about the history of the planet’s climate, as well as the evolution of early human civilizations in the region. A 1997 paper suggested that the shift was a natural consequence of the withdrawal of the glaciers, and has been, until now, traditionally considered to be the most credible explanation.
But the scientists in Seoul said human activities may have encouraged the Sahara’s formation.
“In East Asia there are long established theories of how Neolithic populations changed the landscape so profoundly that monsoons stopped penetrating so far inland,” David Wright, a researcher at Seoul National University, said in a news release.
The spread of scrublands have previously been linked to the desertification of North Africa.
When Wright surveyed archaeological data from the region, he found the movement of early pastoral communities in the Nile Valley tracked closely with the proliferation of scrub vegetation.
Wright and his colleagues suggest the introduction of livestock in North Africa, more than 8,000 years ago, altered the region’s vegetation, suppressing the growth of larger bushes and trees.
Less vegetation left the region’s surface more exposed and reflective, altering the atmospheric conditions. These changes diminished the impact and reach of Africa’s seasonal monsoons, further encouraging the development of scrub vegetation and desert — a feedback loop of desertification.
Wright, whose latest analysis was published in the journal Frontiers in Earth Science, believes lakebed sediments will further illuminate the role humans played in the Sahara’s desertification.
“There were lakes everywhere in the Sahara at this time, and they will have the records of the changing vegetation,” Wright said. “We need to drill down into these former lake beds to get the vegetation records, look at the archaeology, and see what people were doing there.”