During the past 20 years in his research at Boston University, El-Baz has utilized satellite images to better understand the origin and evolution of desert landforms. He is credited with providing evidence that the desert is not man-made, but the result of major climatic variations. His research uncovered numerous sand-buried rivers and streams in the Sahara based on the interpretation of radar images.
These former water courses lead into depressions in the terrain, which he theorized must contain groundwater. His analysis of these data resulted in the location of groundwater in the arid terrains of Egypt, Oman, and the United Arab Emirates (U.A.E.), and perhaps Darfur in Sudan (unless it dried up).
I was surprised to read that the "origin and evolution of desert landforms" was ever considered to have an anthropocenic component.
Question: When was it ever considered that the desert might be "man-made", or otherwise anthropocenically-induced? Is it possible to know which desert was thought to be man-made that El-Baz proved wasn't? Or does the passage refer to all deserts?