AUG 21, 2020 10:29 AM PDT

The megadrought that ended the Green Sahara

Imagine Northern Africa, now inhabited by the desiccated Sahara desert, as a green oasis, covered by plants and trees. That’s what it used to be 11,000-5,000 years ago until it became the hyper-arid Sahara we know now. But what triggered that shift? Now new research published in Nature Communications from scientists at the University of California, Irvine, the University of Pennsylvania, William Paterson University of New Jersey point toward the existence of a megadrought 4,000 to 5,000 years ago.

Using physical evidence in the form of stalagmite samples from caves in Northern Laos, the collaboration of researchers say their findings help reconstruct the mid-Holocene period of Earth’s history.

"In this study, we provide the first proof for a strong link between the end of the Green Sahara and Southeast Asian monsoon failure during the mid- to late Holocene period," said co-author Kathleen Johnson, UCI associate professor of Earth system science. "Our high-resolution and well-dated record suggests a strong connection between Northern Africa and mainland Southeast Asia during this time."

The team measured the geochemical properties of the oxygen and carbon isotopes, carbon-14, and trace metals found in the stalagmites in order to confirm the existence of the megadrought and analyze how it affected the region.

"This is outstanding evidence for the type of climate change that must have affected society, what plants were available, what animals were available," said co-author Joyce White, adjunct professor of anthropology at the University of Pennsylvania. "All of life had to adjust to this very different climate. From an archaeological point of view, this really is a game-changer in how we try to understand or reconstruct the middle Holocene period."

Their findings provide evidence for a shift in the Walker circulation pattern, explain the authors. They write: “Through a set of modeling experiments, we show that reduced vegetation and increased dust loads during the Green Sahara termination shifted the Walker circulation eastward and cooled the Indian Ocean, causing a reduction in monsoon rainfall in mainland Southeast Asia. Our results indicate that vegetation-dust climate feedbacks from Sahara drying may have been the catalyst for societal shifts in mainland Southeast Asia via ocean-atmospheric teleconnections.”

What did the Sahara used to look like? Photo: Pixabay

These conclusions help fill in the gaps of archaeological evidence in interior Southeast Asia during the mid-Holocene. They also imply a reason for understanding the mass migrations that occurred during the time and offer a view on how the development of Neolithic farming in mainland Southeast Asia came to be.

Sources: Nature Communications, Science Daily

About the Author
  • Kathryn is a curious world-traveller interested in the intersection between nature, culture, history, and people. She has worked for environmental education non-profits and is a Spanish/English interpreter.
You May Also Like
AUG 20, 2020
Health & Medicine
New Method to Detect Microplastics in Human Tissues
AUG 20, 2020
New Method to Detect Microplastics in Human Tissues
Microplastics make headlines frequently these days, and a discovery from Arizona State University (ASU) researchers is b ...
AUG 31, 2020
Earth & The Environment
Fossil-tree in the Andean Altiplano dates back 10 million years
AUG 31, 2020
Fossil-tree in the Andean Altiplano dates back 10 million years
The recent discovery of a fossil-tree in the Andean Altiplano dates back to 10 million years ago, say researchers. The d ...
SEP 01, 2020
Chemistry & Physics
No Child's Play - Advanced Bubble Manipulation Method can Transform Chemical Processing
SEP 01, 2020
No Child's Play - Advanced Bubble Manipulation Method can Transform Chemical Processing
Gas bubbles are fascinating, playful objects in children's eyes. In fact, they play an essential role in many indust ...
NOV 17, 2020
Plants & Animals
Taking a Virtual Walk in a Forest Altered by Climate Change
NOV 17, 2020
Taking a Virtual Walk in a Forest Altered by Climate Change
For some people, it's easier to grasp the magnitude of a problem once it can be visualized.
NOV 18, 2020
Plants & Animals
This Bat Species Uses Masks for Mating
NOV 18, 2020
This Bat Species Uses Masks for Mating
From pandemic precautions to televised talent shows, masks are having a moment. Even this bizarre bat species has a buil ...
NOV 18, 2020
Health & Medicine
Rising Temperatures May Increase Tick-Borne Diseases in Humans
NOV 18, 2020
Rising Temperatures May Increase Tick-Borne Diseases in Humans
New research presented at the Annual Meeting of the American Society of Tropical Medicine and Hygiene warns that climate ...
Loading Comments...