Sunday, January 29, 2017

10,000 years ago, the Sahara Desert was one of the wettest areas on Earth

RAIN OUT  Rainier conditions than previously thought turned the Sahara Desert into grasslands, lakes and rivers from 11,000 to 5,000 years ago, a new study finds. A brief return to aridity around 8,000 years ago set the stage for cattle herders to spread across North Africa, researchers suspect.
Thousands of years ago, it didn’t just rain on the Sahara Desert. It poured.

Grasslands, trees, lakes and rivers once covered North Africa’s now arid, unforgiving landscape. From about 11,000 to 5,000 years ago, much higher rainfall rates than previously estimated created that “Green Sahara,” say geologist Jessica Tierney of the University of Arizona in Tucson and her colleagues. Extensive ground cover, combined with reductions of airborne dust, intensified water evaporation into the atmosphere, leading to monsoonlike conditions, the scientists report January 18 in Science Advances.

Tierney’s team reconstructed western Saharan rainfall patterns over the last 25,000 years. Estimates relied on measurements of forms of carbon and hydrogen in leaf wax recovered from ocean sediment cores collected off the Sahara’s west coast. Concentrations of these substances reflected ancient rainfall rates.


Credit: Boing Boing

Rainfall ranged from 250 to 1,670 millimeters annually during Green Sahara times, the researchers say. Previous estimates — based on studies of ancient pollen that did not account for dust declines — reached no higher than about 900 millimeters. Saharan rainfall rates currently range from 35 to 100 millimeters annually.

Leaf-wax evidence indicates that the Green Sahara dried out from about 8,000 to at least 7,000 years ago before rebounding. That’s consistent with other ancient climate simulations and with excavations suggesting that humans temporarily left the area around 8,000 years ago. Hunter-gatherers departed for friendlier locales, leaving cattle herders to spread across North Africa once the Green Sahara returned (SN Online: 6/20/12), the investigators propose. 

Other articles on the same theme:





Story source:


The above post is reprinted from materials provided by Sciencenews . Note: Materials may be edited for content and length.

No comments :

Post a Comment

About me

My photo


  Hello,

    I'm working on a theory for some time in trying to combine science with religion, looking for an answer to the question 
"What is the purpose of life in Creation?  Is it possible for life to be an unintended consequence of our Universe?

Finally due to space,science and exploration throughout the Universe we got everyone to agree with the fact that we are not the only planet with life.  My blog is full of interesting articles about Creation of the Universe with all his laws,  NASA's Missions,  History,   Science,  Physics, Health, Nature, Ancient origins and Culture.