In 4000 BCE, a lake Mega Chad larger than all five Great Lakes covered roughly 360,000 sq km of what is now the Sahara. 6,000 years later, only a tiny fraction, well under 1%, of that ancient lake remains

Thousands of years ago, a vast lake covered an enormous area of what is now the southern Sahara. Known as Palaeolake Mega-Chad, the ancient lake may have reached roughly 360,000 square kilometres, with some estimates exceeding 400,000 square kilometres. Its existence was made possible by the wetter conditions of North Africa’s African Humid Period, when stronger seasonal rains transformed the region.