He explains that the most likely cause for the lake to have grown so large is torrential monsoon rains of a dramatically different climate regime which flooded not only the White Nile but the Blue Nile to the east. Dating of the ancient abandoned drainage channels from the Blue Nile suggest that that branch of the Nile once flowed so heavily it might have backed up the White Nile to make a lake of more than 45,000 square kilometers (17,000 square miles). No dams required.
"It's in the same ballpark as the Great Lakes (of North America)," said Nile lake researcher Ted Maxwell of the Smithsonian Institution, who was not involved in the latest study. "It would be like the Hoover Dam on the Colorado River, only naturally."
To compare, the White Nile mega lake would have been more than half the size of Lake Superior, or, put another way, larger than the combined areas of Lake Erie and Lake Ontario.
"One hundred and ten thousand years ago was very close to when it was very warm and sea level was six meters higher," said Barrows. That created a local climate very different from the desert seen today.
It's also a little confusing, because it was during the glacial period that followed this wet, interglacial time on the Nile that North America saw some of its mega lakes form -- like those that once existed in Utah, Nevada and California.
In other words, the warm climate between ice ages flooded the Nile, but dried up North America. And during the last glacial period the Nile's watershed dried while glaciers filled up the great inland seas of North America.