DAKAR, Sept 13 (Thomson Reuters Foundation) - Large-scale wind and solar farms could more than double rainfall in the Sahara desert, "shocked" scientists said as the region grapples with widespread hunger caused by recurrent drought.
In a simulated model, windmills and solar panels were installed across the world's largest desert - an unrealistic scenario in the near future, experts said.
But the mechanisms discovered may have similar effects on a smaller scale, which further studies could confirm, said Safa Motesharrei, a scientist at the University of Maryland.
"We were expecting increases in rainfall and vegetation, but once we ran our climate model and we saw how large these increases are, we were quite shocked," Motesharrei told the Thomson Reuters Foundation.
The Sahara desert is largely uninhabitable, but the Sahel - a semi-arid belt below it stretching from Senegal to Sudan - is one of the poorest parts of the world with a rapidly growing population that has been hard-hit by climate change.
The latest drought in 2017 triggered a food crisis that left 5 million people in six countries in need of food aid and children at risk of death from malnutrition.
Through changes in air patterns and surface temperature, windmills and solar panels cause moisture to rise and condense into rain, Motesharrei said. The rain boosts plant growth, which in turn causes more rain, the model showed.
At full-scale, the changes would have "major ecological, environmental, and societal impacts", Motesharrei and colleagues said in a paper in Science magazine last week.
If the entire desert were covered in wind farms and one fifth in solar panels, daily average rainfall would more than double to 0.59 millimetres (mm) from 0.24 mm, the study showed.
Even if only the northwest quarter of the Sahara were covered in windmills, rainfall would increase by 0.17 mm per day on average, with the biggest gains in the Sahel.
Location matters, so installations could be placed strategically to maximise effects, said Motesharrei.
Poverty and militancy in parts of the region would make it difficult to install large-scale solar or wind farms even if it were technically feasible, said Oli Brown, an energy and environment expert at London-based think tank Chatham House.
It would also raise problems around land rights and the displacement of indigenous peoples, he said.
"I think covering the Sahara in solar panels and wind farms is highly unrealistic in the foreseeable future," said Brown.
"That said, it's still important and useful to imagine different futures and what unintended consequences, both positive and negative, they might have."
Reporting by Nellie Peyton; Editing Katy Migiro;
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