The Sahara wasn't much of a desert a while back. Satellite images have confirmed the existence of a river network that spanned hundreds of miles and made the region habitable for plants, animals, and humans as recently as 5,000 years ago, according to a French study in Nature Communications. The river network formed during periods of heavy rain that began some 245,000 years ago, according to the study, and it was impressive: If water still flowed through the 320-milelong river system today, it would be the 12th-largest drainage basin in the world. "The present-day Saharan desert was the location of extensive vegetation, animal life and human settlements," the researchers tell the Christian Science Monitor.
The new findings jibe with the theory that there was once a river system feeding into a previously identified underwater canyon found off the coast of Mauritania. A scientist with the UK's National Oceanography Centre tells the Guardian that the discovery is a case study for the drastic results of climate change. “Within just a couple of thousand years, the Sahara went from being wet and humid, with lots of sediment being transported into the canyon, to something that’s arid and dry," he says. An intriguing footnote: The study suggests wet and dry periods have fluctuated in the desert roughly every 20,000 years, meaning "the Sahara could be home to life and vegetation again," observes Quartz. If the pattern holds, it's due for a change in about 15,000 years. (A desert in Chile recently came to life in a colorful way.)