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Think of the Sahara, with its windswept dunes shining in the sun. Some people might see barren land with minimal water or life and hot temperatures. Others see a potential solution to an imminent energy crisis and could potentially make it rain in one of the world's largest deserts.
In an article published this week in Science The researchers discovered that by building huge wind and solar farms across the desert, they could not only provide an impressive amount of electricity in Europe, Africa and the Middle East, but also change the climate, but also increase rainfall. and vegetation in areas that could heavily utilize the added greenery. They estimate that such a business could double the rainfall in the area and increase the vegetation cover by about 20%.
How green are we talking about? The Sahara covers 3.55 million square miles (9.2 million square kilometers). In the study, researchers used computer models that placed wind turbines in the desert at a distance of nearly a kilometer and covered 20% of the desert with solar panels of different configurations (sometimes the panels were checkered) . in other cases they were concentrated in the quadrants). A smaller cover had lower climate impacts – in this case, less precipitation – but a large part also depended on the location of turbines and panels. For example, the installation of panels in the northwest corner had a greater impact than the other three desert options.
Covering parts of the desert with darker solar panels, less sun has bounced off the Saharan sand, which is of an unusually light color, and therefore has a higher albedo than other non-polar deserts. This means that the Sahara usually reflects more light and heat in the air. Reducing albedo by installing darker solar panels could actually increase precipitation in the area while increasing the temperature around the solar panels. The warmer air rises into areas of the atmosphere where it is cooler, and moisture condenses and falls as rain.
"In 1975, Jule Charney, my MIT consultant, proposed a feedback mechanism to explain the drought in the Sahel, a semi-arid transition region south of the Sahara: overgrazing has increased surface albedo (reflectivity), reduced Precipitation and about ten years ago, I had the idea that this feedback would work in the opposite direction in the presence of large solar panel farms, as they would reduce albedo. surface area, "said Eugenia Kalnay, lead author of the document in a press release." Similarly, wind farms would increase surface friction and air convergence, thus producing upward movement and rainfall. "
With more rain, grass and trees could slowly return to the once lush landscape, growing between turbines and solar panels as they do on existing farms.
The solar plant would produce an estimated average of 79 terawatts of electricity, and the wind farm would produce about 3 terawatts, without producing any greenhouse gas emissions. To put this in perspective, the authors say that the world used about 18 terawatts of power last year.
But building a massive solar farm does not happen overnight. Researchers therefore programmed the computer model to determine what would happen during a 100-year accumulation period and for 100 years after plant construction.
"If we can finish building all the wind and solar farms immediately, some of the effects on the atmosphere will be observed almost immediately. But effects due to the vegetation-albedo-precipitation feedback mechanism will take some time to be observed, as the vegetation needs time to develop (in a few years). In fact, the effect would increase as the size of installed wind and solar farms increases, "said two lead authors, Yan Li and Safa Motesharrei, in an email.
Back green
It would not be the first time humans have changed the Sahara. It was a much wetter and greener region than today.
"The Sahara is a vital biome for humanity as a reservoir of cultural and ecological diversity," said David Wright, an archaeologist at Seoul National University. He points out that even today, the region is not just a mass of sand, but mountains, hills and small rivers and lakes with thousands of species.
"Our oldest ancestor known after the separation of our lineage from other monkeys, Sahelanthropus tschadensis, was found in the Sahara. During the humid African period (about 11,000 to 5,000 years), the Sahara was a vast, diverse ecosystem dotted with lakes and fishers. It has become a site of early domestication of cattle and camels and donkeys. It is the site of extensive continental commercial networks run by empires. The Sahara has a lot to teach us about how humans have adapted to climate change in the past, "says Wright.
An article Wright published last year suggested that cattle producers move to the area between 8,000 and 4,000 years ago. Cattle have done what cattle always do, gnawing vegetation and thus improving albedo, thus speeding up the passage from a wetter Sahara to another dry one.
"Human impacts have pushed the natural system to the threshold of desertification and, in places where humans enter ecosystems with their animals, the transition from wet to drought has far exceeded the pace of these pressures. Such changes have been repeatedly demonstrated in the deserts from Atacama to Mongolia and the Sahara, "says Wright, who did not participate in the new Science study.
Researchers have linked climate change to the continued growth of the Sahara. The department has increased by 10% since 1920.
The authors of the more recent article did not consider the other ecological impacts that could be caused by the large installations of wind farms and solar farms in the Sahara, but they think that the increase in rainfall would be a blessing for the inhabitants of the surroundings. Region.
"The world's 10 percent of the world's population produces about 50 percent of the world's carbon emissions. For example, if the world's poorest 90 per cent of the world's population aims to raise their standard of living to the richest 10 per cent using fossil energy, this would increase total energy consumption and global emissions of greenhouse gases. greenhouse five times. Motesharrei says in an email. To give the whole world access to development – without pushing climate change even further – the authors argue that we need as much clean, renewable energy as possible.
The prospect of intentionally changing the climate is obviously fraught with ethical questions. But Wright points out that we have already done it. "Humans are, by nature, niche builders. We have evolved as niche builders and our niche construction activities will have one of two possible outcomes: either it will save our species from extinction or it will condemn us to extinction. Human societies have already placed great ecological footprints in desert and semi-desert environments, "he says. "In terms of willingness, yes, people are certainly willing and able to build dozens of power plants in the deserts and semi-deserts of Africa. It is prudent to know if it is safe to do so. This study suggests that it is cautious, but as they say, there are more costs for such projects than just green.
An analysis of the costs and benefits of a project that changes the world is discouraging under the best of circumstances, but the stakes are particularly high. Especially for people who already live in the area.
"It is up to local people to determine if they are ready to play on the development of energy infrastructure, which could have recursive effects within the broader ecology of the region," says Wright. "In the context of the geopolitics of the industrial era, such development projects should benefit very few people in the areas where they are built, even if the ecological impacts will be the most serious. The benefits will go to the already developed regions of the world, which bear no risk and reap only the benefits, "Wright says.
The authors of the paper also advise a thoughtful approach to any action that might be taken in the future.
"The establishment of such large-scale solar and wind farms has become increasingly possible, but requires appropriate planning and visionary decision-making, as well as the cooperation of decision-makers, companies, stakeholders and people. . We hope that all these actors and local and global actors will cooperate and make it a reality, "write Li and Motesharri. "This could be the best chance to support life on this planet while improving the quality of life for all."
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