A team of scientists has concluded that deploying solar and wind farms across the region that the Sahara encompasses will produce significantly more rain, and therefore, natural vegetation, in the areas that they would exist. In what the study refers to as “albedo—precipitation—vegetation feedback” (albedo is basically the reflection of incident light and electromagnetic radiation), the models that scientists used would increase precipitation by 1.12 mm per day (.0441 inches). Translation? 16 inches per year of increased rain. That’s 16X what normally occurs in the most arid parts of the Sahara, and double that of the Sahel.
The researchers simulated the effects of around 79 terawatts of solar panels and 3 terawatts of wind turbines.
The system would need 9 million square kilometers (this is the area of Canada), which presents challenges for the political, social, and economic systems that all of the 10 countries that would be involved have in place. Also, wind farms would initially — before natural vegetation grew and began to cool things and change the cycles — raise temperatures by 2 degrees C. Solar, 1 degree C.
More energy, more rain
Energy generation by wind and solar farms could reduce carbon emissions and thus mitigate anthropogenic climate change. But is this its only benefit? Li et al. conducted experiments using a climate model to show that the installation of large-scale wind and solar power generation facilities in the Sahara could cause more local rainfall, particularly in the neighboring Sahel region. This effect, caused by a combination of increased surface drag and reduced albedo, could increase coverage by vegetation, creating a positive feedback that would further increase rainfall.
Wind and solar farms offer a major pathway to clean, renewable energies. However, these farms would significantly change land surface properties, and, if sufficiently large, the farms may lead to unintended climate consequences. In this study, we used a climate model with dynamic vegetation to show that large-scale installations of wind and solar farms covering the Sahara lead to a local temperature increase and more than a twofold precipitation increase, especially in the Sahel, through increased surface friction and reduced albedo. The resulting increase in vegetation further enhances precipitation, creating a positive albedo–precipitation–vegetation feedback that contributes ~80% of the precipitation increase for wind farms. This local enhancement is scale dependent and is particular to the Sahara, with small impacts in other deserts.