How building a massive solar farm in the Sahara desert could disrupt the climate

Researchers from Sweden warn that installing an enormous array of solar panels in the Sahara desert can drastically alter the climate.

In a study published in the journal Geophysical Research Letters, the researchers described how a giant array of solar panels, such as that planned for the Sahara, could raise global temperatures. This could disrupt precipitation patterns and bring more cyclones to different regions around the world.

How a Sahara solar farm could harm the environment

The Sahara, the world’s largest desert, is a prime location for a giant solar farm. Like all deserts, it is spacious, mostly flat, never short of sunlight and rich in silicon – the raw material for the semiconductors from which solar cells are made. Studies show that installing solar panels in the Sahara may be able to provide more than four times the world’s total energy use.

But while solar power is a clean, renewable source of energy, harvesting it using solar panels is another matter altogether. Ecologists Benjamin Smith and Zhengyao Lu, professors of ecosystems science at Lund University and two of the study researchers, explained that only around 15 percent of solar energy gets converted to electricity. The rest, they noted, is returned to the environment as heat.

“The panels are usually much darker than the ground they cover, so a vast expanse of solar cells will absorb a lot of additional energy and emit it as heat, affecting the climate,” the pair explained in an article for the Conversation.

If this effect were only local, Smith and Lu continued, it might not matter for a sparsely populated desert. But the scale of the installations needed to make a dent in the world’s fossil fuel demand would be vast. As such, the environmental impact of an enormous solar farm will likely be widespread.

That said, past studies have produced a somewhat more optimistic picture. A 2018 study suggested that covering 20 percent of the Sahara with solar panels would boost local rainfall and encourage plant growth. But according to Smith and Lu, these studies assumed that atmospheric conditions and ocean temperatures would remain constant.

Environmental impact of a massive Saharan solar farm

The researchers developed a complex model of the Earth to examine how a massive Saharan solar farm would interact with various components of the environment, including the atmosphere and oceans. The model showed that local temperatures would rise by 2.7 degrees and 4.5 degrees if solar panels covered 20 percent and 50 percent of the Sahara, respectively.

This warming, according to the researchers, would eventually spread around the globe due to the influence of the atmosphere and oceans. Global average temperatures would rise by 0.29 degrees for a 20 percent coverage and 0.7 degrees for a 50 percent coverage.

The new heat source in the Sahara would also reorganize global air and ocean circulation. In turn, the narrow band of heavy rainfall in the tropics, which makes up more than 30 percent of the global precipitation and supports the Amazon and Congo Basin rainforests, would shift northward.

The Amazon then would experience more droughts because less moisture would arrive from the ocean. Meanwhile, tropical cyclones would hit North American and East Asian coasts more frequently.

But the real-world impact of a Saharan solar farm could be much worse than the model suggested. The researchers noted that they did not account for other important factors such as the dust blown from the Sahara. The latter is a vital source of nutrients for the Amazon and the Atlantic Ocean. (Related: Solar power is neither as clean nor as sustainable as environmentalists make it out to be.)

TheConversation.com

SmithsonianMag.org

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