A new study, reported in the journal Science, has shown that large-scale solar and wind farms could increase rainfall and vegetation, even in the Sahara desert. Yan Li, lead author and postdoctoral researcher in natural resources and environmental sciences at the University of Illinois, declares that the study is among the first to model the climate effects of wind and solar installations while taking into account how vegetation responds to changes in heat and precipitation.
Switching from fossil fuels to renewable energy is an important and necessary step towards averting climate change. However, in our efforts to go green, we also need to be mindful of other consequences, both intended and unintended – and that includes how a mass deployment of renewable technology might affect its surrounding climate.
Yan Li and colleagues, Eugenia Kalnay and Safa Motesharrei, found that all those hypothetical wind turbines and solar panels would make their immediate surroundings both warmer and rainier, and could turn parts of the Sahara green for the first time in at least 4,500 years.
“We chose it because it is the largest desert in the world”, said Li, “it is sparsely inhabited, it is highly sensitive to land changes and it is in Africa and close to Europe and the Middle East, all of which have large and growing energy demands” .
they found that wind farms caused a warming of near-surface air temperature, with larger differences in cooler temperatures, rather than warmer ones. The turbines mix ground air vertically leading to a greater nighttime warming by bringing warmer air from above. These changes would affect the microclimate, and if the installations were truly huge they could truly alter climate on a continental scale. Solar panels mean more solar radiation is absorbed and less of the sun’s energy is reflected back into space. This causes the land surface to warm up.
“We found that the large-scale installation of solar and wind farms can bring more rainfall and promote vegetation growth in these regions,” Kalnay said. “The rainfall increase is a consequence of complex land-atmosphere interactions that occur because solar panels and wind turbines create rougher and darker land surfaces.
While not a blueprint for the immediate future, the study shows that these power sources could have more beneficial effects, and installations in arid or semi-arid regions could help agriculture, economic development, and social wellbeing.