Nahaufnahme einer Gruppe Keimlinge, die aus dem Wüsten-Sand sprießen.



—— Deserts such as the Sahara are continually expanding, and humankind is responsible for some of this desertification. Now there are large projects to help halt this expansion, but it isn’t easy to reclaim land from the desert.

Nothing but sand dunes as far as the eye can see. The sun shines mercilessly here at the edge of the Sahara Desert. It’s the world’s largest arid desert. Welcome to Sardinia!

But wait a minute, isn’t there some mistake? While the Sahara and Sardinia might start with the same two letters, there are at least six degrees of latitude between the northern stretches of the African desert and the Italian island. Yet the Sahara is growing; by the year 2100, it could extend as far as Europe, turning parts of Spain, Italy, Greece and Turkey into desert.

Researchers agree that the Sahara has been expanding for quite some time, and almost continuously, however there is disagreement about the exact pace and extent. Nonetheless, recent examples show that the situation is serious indeed. In Libya, for instance, the desert now eats its way up to 500 kilometers into the country during the dry season. In Mali, a terribly poor, land-locked country in Western Africa that is already 65 percent covered by deserts and semi-arid areas, the Sahara advances dozens of kilometers every year.

The consequences of these developments could be dramatic. Agriculture and forestry will become impossible, while biodiversity decreases. A total of 12 million hectares of fertile soil are lost every year, particularly in poorer countries. In response, non-governmental organizations and authorities in affected regions are taking countermeasures to reclaim land from the desert or to at least stop the desert’s expansion. But, as experts warn, although the intentions are good, the projects themselves aren’t always well thought out.

Thus the goal is to address the factors disrupting the particular ecosystem.

One of these experts is Thomas Wagner, a biologist at Munich’s Technical University, where he holds the Chair of Renaturation Ecology. Wagner is cautious about using the term renaturation in the struggle against expanding deserts, however. “The desert is, of course, a part of the natural world that develops where there is little rainfall,” he explains. Deserts also sometimes expand quite naturally, for instance when there are longer periods of drought. Experts therefore distinguish between the natural process of the expansion of arid areas and human-caused desertification. “Only with the latter does it even make sense to fight against desertification,” Wagner says.

Although it may be difficult to determine the underlying causes in any given case, there are three human factors considered to be triggers of desertification: over-grazing, overuse through agriculture and deforestation.

Thus the goal is to address the factors disrupting the particular ecosystem. “Deforestation and over-grazing must stop,” Wagner says. “That of course means that we have to address complex processes, including socioeconomic ones.” If local farmers continue to allow their cattle to graze in the affected areas, any attempts to combat desertification become futile.

This is why many attempts to stop desertification ultimately fail. “You must learn and work with the local customs on the ground, which are often different from region to region, even within the same country,” Wagner says. Then it’s a matter of making sure that the residents of a particular region can continue efforts on their own even after project officials leave the area. Low-tech solutions offer the best approach. “For example, drilling wells for irrigation is important, but you’re more likely to succeed with a hand-dug well,” he explains. More elaborate projects endanger the long-term success because of the risk of misappropriation of funds or materials.

“Deforestation and over-grazing must stop.”

Thomas Wagner, biologist at Munich’s Technical University

Experts have great hopes for the Great Green Wall in Africa, a project led by the African Union to stop desertification in the Sahel region. Reforestation and restoration of dehydrated and damaged soil are intended to create a sort of protective wall of greened and agricultural areas stretching from the Atlantic coast to the Horn of Africa, with 21 countries participating. The Great Green Wall was initially just about planting trees, but studies of other prominent role model projects concluded that this approach was too one-dimensional.

Back in 1978, China started building its own Great Green Wall to hold back the Gobi Desert. The project is still ongoing and is expected to be completed by the year 2050, at which point the wall will be 4,500 kilometers long. However, there are a large number of issues: the massive planting of trees has caused ground-water problems in areas of northern China, and the Chinese have been planting fast-growing tree species, putting a strain on local biodiversity.

That is why Africa’s Great Green Wall is taking a more holistic approach, with stakeholders also taking into account social, economic and environmental aspects. The problem is that the project hasn’t yet made much progress. The Great Green Wall is supposed to be completed in 2030. Yet by autumn 2020, 13 years after the project’s kickoff and thus about halfway through to completion, just 4 percent of the planned area has actually been planted. To achieve the goals, investments of more than 4 billion US dollars are needed—every year.

Despite these issues, Wagner still believes that Africa’s Great Green Wall has a chance to solve the problems of desertification. “Those responsible for the project are thinking big and getting buy-in from the local populations,” he says. He further recommends that the Western world begin tackling the issue of desertification at home, too, since the phenomenon is likely to become a major issue sooner rather than later. “In Spain, around Almeria, and around the Ogallala Formation in the Great Plains of the US, we see areas that could be threatened by desertification,” he warns.