A new study has found that, Sahara desert contained the world’s largest freshwater lake until it evaporated in just a few hundred years. Researchers from the University of London used satellite images to map abandoned shore lines around Palaeolake Mega-Chad. They had analysed sediments to calculate the age of these shore lines, producing a lake level history spanning the last 15,000 years.

At its peak around 6,000 years ago, Palaeolake Mega-Chad was the largest freshwater lake on Earth, with an area of 3,60,000 square km. Today’s Lake Chad is reduced to a fraction of that size, at only 355 square km.  The 137-square-mile Lake Chad was only a fraction of the 139,000-square-mile Mega-Chad.

The drying of Lake Mega-Chad reveals a story of dramatic climate change in the southern Sahara, with a rapid change from a giant lake to desert dunes and dust, due to changes in rainfall from the West African Monsoon. By examining the borders of Lake Chad, the researchers found evidence of a significant change in climate over the past 6,000 years. Mega-Chad had possibly shrunk from drying out.