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Using fossil plant molecules to track down the Green Sahara

ScienceDaily (May 31, 2021

Titre : Using fossil plant molecules to track down the Green Sahara

Researchers explain how vegetation was possible in the desert

ScienceDaily (May 31, 2021 )

Résumé
The Sahara has not always been covered by only sand and rocks. During the period from 14,500 to 5,000 years ago large areas of North Africa were more heavily populated, and where there is desert today the land was green with vegetation. This is evidenced by various sites with rock paintings showing not only giraffes and crocodiles, but even illustrating people swimming in the "Cave of Swimmers." This period is known as the Green Sahara or African Humid Period. Until now, researchers have assumed that the necessary rain was brought from the tropics through an enhanced summer monsoon. The northward shift of the monsoon was attributed to rotation of the Earth’s tilted axis that produces higher levels of solar radiation over North Africa approximately every 25,000 years. However, climate models have not been able to simulate plant growth sufficient to create a Green Sahara with rain that stem only from the summer monsoon. Scientists are convinced that permanent vegetation at that time in North Africa cannot be explained by a single rainy season each year.

Story Source  : MARUM - Center for Marine Environmental Sciences, University of Bremen

Annonce (ScienceDaily)

Page publiée le 6 juillet 2021