The Sahara was ‘green’ for over 6,000 years
and had 10 times more rain than now

According to a new study recently published in the journal Science Advances, evidence shows
that humans occupied much of the Sahara during the ‘wet period’ around 8,000 years ago.

Through an analysis of marine sediments, researchers at the University of Arizona have determined
rainfall patterns in the Sahara over a period of 6,000 years obtaining fascinating results. The UA-led
team has identified the climate pattern that generated a “Green Sahara” from 5,000 to 11,000 years
ago. The region had 10 times the rainfall it does today.

As it turns out, what is now the Sahara Desert was the home of hunter-gatherers who lived off the
animals and plants present in the savannas of the region and off the wooded prairies sometime
between 5,000 and 11,000 years ago.

“It was 10 times as wet as today,” said lead author Jessica Tierney of the University of Arizona.
Annual rainfall in the Sahara now ranges from about 4 inches to less than 1 inch (100 to 35 mm).

Although other research has already identified the existence of a “Green Sahara” period, Tierney
and colleagues managed to compile a continuous record of rainfall in the region that existed 25,000
years ago.

Interestingly, archaeological evidence shows that humans occupied much of the Sahara during the
wet period, but gradually withdrew some 8,000 years ago.

Other researchers have suggested that the Sahara became drier by the time people left, but the
evidence was inconclusive, says Tierney, an assistant professor of geosciences at the UA, whose
work was published in Science Advances.

The Sahara Desert is the warmest in the world and the third largest after Antarctica and the Arctic.

According to the new study, rainfall records gathered by the team indicate a period that lasted for
one thousand years, some 8,000 years ago, in which the Sahara became drier, which coincides with
the time when people left.

“It looks like this thousand-year dry period caused people to leave,” Tierney said.

“What’s interesting is the people who came back after the dry period were different — most raised
cattle. That dry period separates two different cultures. Our record provides a climate context for
this change in occupation and lifestyle in the western Sahara.”

According to UA News, Instead of lake sediments, Tierney and her colleagues used cores of marine
sediments taken off the coast of West Africa at four different sites. Because the cores were taken
over a north-south distance of about 800 miles (1,300 km) — from offshore Cape Ghir, Morocco, to
the northwestern corner of Mauritania — the cores revealed both the ancient rainfall patterns and
the areal extent of the Green Sahara.