THE quest to colonise Mars will require not just advances in rocket technology but also a way to terraform the merciless Martian soil fertile. To do that, you need to first cover it with water that’s stable, which is easier said than done. There’s actually water already on Mars but it’s all frozen now.
Terraforming Mars could literally require heating up the planet. There are several theories on how that could be done, including manufacturing super-greenhouse gasses but none of it will be easy. Meanwhile, the technology to do any of these things are far from ready.
What is significantly more feasible would be terraforming deserts here on earth, most of which are arid and inhabitable because the land is not fertile and no crops can grow there. But what if we could terraform the Sahara Desert?
Well, there are several ambitious plans to do just that. It would be a major undertaking. The Sahara is 8.6 million square km in size or roughly the size of the United States. Imagine if all that arid, barren land could be converted into a lush green landscape. Not only would it then become a source of produce, providing the world with food, it would also help to remove some 7.6 billion tons of carbon dioxide a year.
To do this would require a large amount of water. This would need to be obtained from the sea and desalinated. One proposal is to flood the vast desert with water. Another is to have the water carried in underground pipes. This would prevent evaporation and allow the water to reach the roots of plants directly.
It wouldn’t just be any plants though. Initially, it would have to be plants and trees that can thrive in hot climates. As these plants and trees grow, they would change the soil, replenishing it with nutrients and therefore making it more fertile for other plants to be grown there.
This all sounds great, so why aren’t we doing it? Unlike the Mars terraforming project, the technology needed for terraforming the Sahara isn’t that complex. It will be expensive though.
FLOODING, WIND AND SOLAR
A Silicon Valley venture capital company called Y Combinator recently unveiled a desert flooding plan as a potential remedy for global warming that would involve 900 trillion litres of desalinated water. Just to desalinate and pump the ocean water into the desert would require an electrical grid far greater than what exists anywhere on earth right now. The company estimates the total bill to be a whopping US$50 trillion. And that’s just enough to flood about half the Sahara, not the whole thing.
Y Combinator’s President Sam Altman has admitted in an interview that the cost for any programme like this would need to drop from the trillion-dollar level to the billion-dollar level to be practical.
A different approach that doesn’t involve flooding the desert with so much water is one that utilises solar and wind farms across the desert. A new climate-modelling study published in the journal Science last year found that a massive wind and solar installation in the Sahara Desert and neighbouring Sahel region would increase local temperature, precipitation and vegetation.
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, said lead author Yan Li, a postdoctoral researcher in natural resources and environmental sciences at the University of Illinois.
CONSIDERATIONS AND DISCOVERIES
“Previous modelling studies have shown that large-scale wind and solar farms can produce significant climate change at continental scales,” Li said in a statement. “But the lack of vegetation feedbacks could make the modelled climate impacts very different from their actual behaviour.”
The study, which was done together with Eugenia Kalnay and Safa Motesharrei at the University of Maryland, focused on the Sahara for several reasons, according to Li.
“We chose it because it’s the largest desert in the world; it’s sparsely inhabited; it’s highly sensitive to land changes; and it’s in Africa and close to Europe and the Middle East, all of which have large and growing energy demands,” he said.
The wind and solar farms simulated in the study would cover more than 9 million square km and generate, on average, about 3 terawatts and 79 terawatts of electrical power, respectively. “In 2017, the global energy demand was only 18 terawatts, so this is obviously much more energy than is currently needed worldwide,” Li said.
Precipitation also increased as much as 0.25 millimetres per day on average in regions with wind farm installations. In the Sahel, average rainfall increased 1.12 millimetres per day where wind farms were present. “This increase in precipitation, in turn, leads to an increase in vegetation cover, creating a positive feedback loop,” Li said.
Solar farms had a similar positive effect on temperature and precipitation, the team found. “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.
“The increase in rainfall and vegetation, combined with clean electricity as a result of solar and wind energy, could help agriculture, economic development and social well-being in the Sahara, Sahel, Middle East and other nearby regions,” concluded Motesharrei.
Oon Yeoh is a consultant with experiences in print, online and mobile media. Reach him at [email protected].