Impacts of Large-Scale Sahara Solar Farms on Global Climate and Vegetation Cover

Large-scale photovoltaic solar farms envisioned over the Sahara desert can meet the world's energy demand while increasing regional rainfall and vegetation cover. However, adverse remote effects resulting from atmospheric teleconnections could offset such regional benefits. We use state-of-the-art Earth-system model simulations to evaluate the global impacts of Sahara solar farms. Our results indicate a redistribution of precipitation causing Amazon droughts and forest degradation, and global surface temperature rise and sea-ice loss, particularly over the Arctic due to increased polarward heat transport, and northward expansion of deciduous forests in the Northern Hemisphere. We also identify reduced El Nino-Southern Oscillation and Atlantic Nino variability and enhanced tropical cyclone activity. Comparison to proxy inferences for a wetter and greener Sahara similar to 6,000 years ago appears to substantiate these results. Understanding these responses within the Earth system provides insights into the site selection concerning any massive deployment of solar energy in the world's deserts. Plain Language Summary Solar energy can contribute to the attainment of global climate mitigation goals by reducing reliance on fossil fuel energy. It is proposed that massive solar farms in the Sahara desert (e.g., 20% coverage) can produce energy enough for the world's consumption, and at the same time more rainfall and the recovery of vegetation in the desert. However, by employing an advanced Earth-system model (coupled atmosphere, ocean, sea-ice, terrestrial ecosystem), we show the unintended remote effects of Sahara solar farms on global climate and vegetation cover through shifted atmospheric circulation. These effects include global temperature rise, particularly over the Arctic; the redistribution of precipitation (most notably droughts and forest degradation in the Amazon) and northward shift of the Intertropical Convergence Zone; the northward expansion of deciduous forests in the Northern Hemisphere; and the weakened El Nino-Southern Oscillation and Atlantic Nino variability and enhanced tropical cyclone activity. All these remote effects are in line with the global impacts of the Sahara land-cover transition similar to 6,000 years ago when Sahara desert was wetter and greener. The improved understanding of the forcing mechanisms of massive Sahara solar farms can be helpful for the future site selection of large-scale desert solar energy facilities. Key Points . A set of state-of-the-art Earth-system model simulations are used to study the impacts of large-scale (20% coverage or more) Sahara solar farms These hypothetical solar farms increase local rainfall and vegetation cover through positive atmosphere-land(albedo)-vegetation feedbacks Conveyed by atmospheric teleconnections, the Sahara solar farms can induce remote responses in global climate and vegetation cover

Automated summary

Large-scale photovoltaic solar farms in the Sahara desert can meet the world's energy demand and increase regional rainfall and vegetation cover, but they may also have adverse remote effects such as Amazon droughts, global temperature rise, and sea-ice loss. Using advanced Earth-system model simulations, researchers have found that Sahara solar farms can cause global precipitation redistribution, changes in surface temperature, forest degradation, and enhanced tropical cyclone activity. Understanding these remote effects is crucial for selecting suitable sites for massive deployment of solar energy in deserts.