Fossil rivers of the Sahara tell of the threat of warming

A satellite image shows the morphologies of fossil rivers in southern Egypt. This study shows that these rivers were intensely active during the African wet period. Esri World Imagery - A UNIGE-led team has studied the fossil rivers of the Egyptian Sahara to reconstruct the region's rainfall rates that led to a major migration of people away from the Nile valley 10,000 years ago. Why did the people living near the Nile river migrate to central Egypt 10,000 years ago, when the Egyptian Sahara was still green? Geologists led by the University of Geneva , Switzerland, have studied the fossil rivers north of Lake Nasser in Egypt in order to reconstruct the palaeo-hydrology of the region and to determine the rainfall rate of this African humid period. They found that following a rapid temperature increase of about 7°C, the frequency of heavy rainfall events increased fourfold, increasing river flooding and forcing riverine populations to migrate to the center of the country. These results, to be read in the journal Quaternary Science Review , highlight the increase in extreme weather episodes in the event of global warming. Africa experienced a wet period between 14,800 and 5,500 BC, characterized by a still green Sahara.