A climate simulation showed that the real age of the Sahara Desert is more than twice than previously thought.
Current geological data settled that the Sahara is roughly 2 to 3 million years old. However, Zhongshi Zhang, a paleoclimatologist from the Bjerknes Centre for Climate Research in Bergen, contradicted that the arid region might be more than three million years old.
Zhang's claim is based on a climate simulation study conducted to reveal the actual age of the world's largest desert. The authors also cited another research, performed decades ago, stating that there were dune deposits that were more than 7 million years old found in Chad. The analysis also pointed out that sediments of dust and pollen gathered from the seafloors of northern Africa revealed episodes of dry spells as early as 8 million years ago.
The researchers also attempted to discern the cause of the desertification of Sahara. Some of the possible causes presented in the climate simulation include changes in the Earth's orbit, variations on the carbon dioxide levels, and the shift in land masses.
The shift in land masses occurred when the Tethys Sea shrank as the African tectonic plate inched its way towards the north, near the Eurasian plate. This tectonic shift created a change in the weather around 7 to 11 million years ago, weakening the African monsoon during summers. As the winds shifted its path, the moisture that northern Africa coming from Atlantic decreased, resulting to Sahara desert's semi-arid climate.
Geologist Stefan Kröpelin from the University of Cologne in Germany told Nature News that the simulations presented remarkable claims, but these were based on "numerical speculation based on almost non-existent geological evidence." He explained that there is no evidence yet to conclude the actual size of the Tethys Sea.
"Nothing you can find in the Sahara is older than 500,000 years, and in terms of Saharan climate even our knowledge of the past 10,000 is full of gaps," Kropelin added.
Further details of the study were published in the journal Nature.
