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Roots of the Sahara Desert Go Back Seven Million Years

Amita Vadlamudi

Amita Vadlamudi has an extensive IT background focused on the analysis of mainframe and distributed systems. Drawn to climate and weather patterns as an area of particular interest, Amita Vadlamudi has an abiding fascination with the ways in which deserts come into being.

Regarding the formation of the Sahara Desert, a 2014 study by Norwegian researchers points to a gradual desertification process that started at least 7 million years ago. As revealed by ancient sand dune deposits discovered in northern Chad, North Africa’s paleoclimate changed rapidly between 7 and 11 million years ago, during the Late Miocene epoch’s Tortonian stage. As aridity increased the Tethys, a massive ocean that encompassed what are now the Mediterranean, Caspian, and Black seas, began to shrink rapidly.

This in turn diminished wind circulation associated with the summer monsoons and increased the sensitivity of the monsoon period (and its associated rains), creating a phenomenon known as “orbital forcing.” This permanently shifted the region from a lush landscape to one that followed orbital timescales in alternating between humid and arid cycles. Ultimately, the process generated an expanding desert environment that received very little rainfall and grew to encompass nearly 10 percent of the African continent.

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