How the Desert Could Bloom

A new University of Maryland-led study published today in Science shows that wind and solar farms in the Sahara would lead to a doubling of rainfall in the earth’s largest hot desert, potentially opening large expanses to agriculture.

The primary effect of such renewable energy farms would be a reduction of human-generated greenhouse gas emissions. But large-scale wind and solar farms could also affect land surface properties and alter the regional climate. An international team led by UMD researchers explored these potential impacts using a novel, interactive combination of a global climate model and a land/vegetation model.  

Large-scale solar and wind farms in the Sahara would more than double the precipitation in the Sahara, said Yan Li, a former UMD postdoctoral researcher and a lead author of the paper. The study found the most substantial increase would occur in the Sahel, a semi-arid region bordering the Sahara, where the rainfall increase could range from an estimated 8 to 20 inches. Vegetation cover could jump about 20 percent, he said.

Such precipitation increases could lead to substantial improvements of rain-fed agriculture in the region, and vegetation increases would lead to the growth in production of livestock, said Safa Motesharrei, UMD systems scientist and another lead author of the paper.

“The Sahara, the Sahel and the Middle East include some of the driest regions in the world, while experiencing high growth of population and poverty,” he said. “Our study has major implications for addressing the intertwined sustainability challenges of the energy–water–food nexus in this region.”

The combination of the climate and vegetation models resulted in unexpected new findings, said a climate scientist who was not involved with the study.

“While it was known that surface roughness and albedo [reflectivity] can affect climate and rainfall, the conclusion that including dynamic vegetation would lead to a strong positive feedback in rainfall is new,” said J. Shukla, a Distinguished University Professor of Climate Dynamics at George Mason University.

 Other Department of Atmospheric and Oceanic Science scientists involved in the study were a Distinguished University Professor Eugenia Kalnay, doctoral candidate Eviatar Bach, Associate Professor Ning Zeng and Adjunct Associate Professor Daniel Kirk-Davidoff.

This article has been updated to reflect Safa Motesharrei's current job title.