Solar Farms In The Sahara Might Have An Unexpected Effect On The Global Climate

When picturing the Sahara Desert, besides the endless sand, you'll also imagine blue skies and a blazing sun. While it might seem like the perfect place for a vast solar farm, climate scientists found that building such facilities on a massive scale there could have significant consequences not only for the Sahara, but also for the climate thousands of miles away.

A 2020 study investigated what might happen if huge solar farms, like those in Tibet, were built across the Sahara. Solar panels are darker than the Sahara's pale sand, so panels would absorb more sunlight and affect how heat is exchanged between the land and the atmosphere. In the researchers' model, the warming surface could alter air circulation, leading to more rainfall. Increased vegetation, as has also been observed around solar farms in China, could then reinforce the warming and wetter conditions. While that might sound like a welcome scenario for a part of the world known for its dry climate, the effects could extend far beyond the desert, with the model suggesting that changes in atmospheric circulation could make some regions around the world wetter and others drier.

In fact, the model's simulations suggested possible droughts and forest degradation as far away as the Amazon, along with rising global surface temperatures and Arctic warming that could contribute to further losses of sea ice. It should be noted, however, that these are modeled outcomes, and not certainties, and that the study examined hypothetical, extremely large solar installations (20% coverage of the Sahara). While solar power is an important tool for reducing greenhouse gas emissions, the research highlights the possibility that changing an enormous area of land to generate clean energy could create unexpected pressures on Earth's climate.

A green and lush Sahara may sound far-fetched, but during the African Humid Period around 6,000 years ago, much of the region was in fact much wetter and supported far more vegetation than it does today, a transformation linked to changes in rainfall patterns and ecosystems. The researchers in the 2020 study on Sahara solar farms suggest that similarly large-scale changes to the region's surface could have significant effects on the wider climate

In the researchers' simulations, the Intertropical Convergence Zone, a band of rising air near the equator that influences tropical rainfall, moves northward. This could bring rain to some areas while leaving others drier, contributing to the risk of drought and forest degradation in the Amazon. The model also projects a northward expansion of deciduous forests in the Northern Hemisphere, weaker fluctuations in the Pacific and Atlantic climate patterns known as El Niño Southern Oscillation and Atlantic Niño, and increased tropical cyclone activity. The changes reflect the complex interactions between the atmosphere, oceans, sea ice, and ecosystems.

When it comes to the idea of building huge solar panel facilities in the Sahara, the researchers point out the need for careful site selection and more efficient panels to limit the possible adverse effects. Their simulations suggest that the scale of the deployment affects the extent of the impact on remote climates. The findings underline the importance of assessing the wider environmental consequences of clean energy projects. For the hypothetical Sahara solar project and others like it, extensive research is needed to determine if, and to what extent, the climate could be affected.