**Martin Williams *is professor emeritus and adjunct professor of earth sciences at the University of Adelaide. His many books include Climate Change in Deserts *; Nile Waters, Saharan Sands; and The Nile Basin. He lives in Glenalta, South Australia.

**Martin Williams *is professor emeritus and adjunct professor of earth sciences at the University of Adelaide. His many books include Climate Change in Deserts *; Nile Waters, Saharan Sands; and The Nile Basin. He lives in Glenalta, South Australia.