Africa was building a giant wall of trees. The plan, launched by the African Union in 2007, aiming to plant a belt of trees that spanned 11 countries and measured 8,000 kilometers, had little chance to succeed. Despite the fantasy of completing the largest living structure on the planet, three times the size of the Great Barrier Reef, lack of funding and science did not support its creation. The goal of the campaign was to restore 100 million hectares of degraded land across the Sahel in Africa. A semi-arid region extending from Senegal to Djibouti, the Sahel serves as an intermediate zone between the Sahara Desert to the north and savannas to the south. While people previously believed that the Sahara Desert was moving south into the Sahel, the landscape has become degraded not due to an encroaching desert, but by overuse of the region’s soil. Although the cause of this deterioration is different than was thought, communities throughout the area are participating in effective indigenous land use techniques to restore the terrain tormented by desertification.
The dream of the Great Green Wall began in the 1970s when large swaths of formerly fertile land in the Sahel became severely degraded. Over 46 percent of African land in this region has been damaged by desertification. Desertification is the process by which areas that experience little precipitation and humidity are converted to degraded landscapes. Natives quickly realized that change was necessary to combat the cycle of poverty, shortages in food and water, forced migrations, and developing conflicts over critical resources in the region. In the 1980s, massive famines, due to the disappearance of livestock and destruction of crops, struck the Sahel, each affecting millions of people. Community leaders advocated for a Great Green Wall. While significant progress has been made in growing this expanse of trees, especially in countries like Ethiopia (which has restored over 15 million hectares of degraded land), and in Senegal (which has already grown 12 million trees), these trees would remain unprotected in uninhabited areas. This lapse in judgement in the planning of the wall reveals a flaw that allowed desertification in the Sahel initially.
Naturally-fluctuating weather patterns and human activities such as overgrazing and irresponsible agricultural practices are key causes of land degradation. As stated in an article from Greentumble, poor farming practices, including over-cultivation, cause excessive use of farmland to “the point where productivity falls due to soil exhaustion.” Soil exhaustion, which can damage land and lead to desertification, was driven by a high demand for food production in the Sahel, to address the growing population and generate revenue in an agrarian economy.
Over-cultivation leads to soil degradation and erosion, and as more topsoil is exposed, the quality of the fertile layer of soil near the surface, humus, is sharply reduced. The editorial from Greentumble also explains that a decline in soil fertility leads to decrease in profitability in agricultural activities, “which in turn is a major cause of poverty and hunger in sub-Saharan Africa, where one in three people (are) undernourished.” The aim of the Great Green Wall was to reverse these negative effects and revitalize the Sahel’s soil and agricultural economy.
The Great Green Wall would have consisted of drought-resistance acacia trees. Acacia trees are pioneer species, so they can grow quickly, even in a desert landscape, and are able to attract additional plants and animal species. Acacias cool surrounding air by releasing moisture and provide abundant shade to reduce soil’s exposure to harsh African sunlight. The roots of acacia trees also hold water to provide resistance against drought. In terms of food and economic contributions, acacias are abundant resources that can be used for much more than improving soil quality. Livestock can feed off the leaves of these trees, and their seeds provide a food source for people and animals. A National Geographic article describes the acacia senegal tree, which is a “staple plant in the Great Green Wall,” and “produces gum arabic, a main ingredient in consumer products such as cosmetics and soft drinks.” Acacia trees have vast potential that could have been utilized within the structure of the Great Green Wall, and can still be implemented in reforestation projects throughout Africa.
In addition, the growth of acacia trees offsets carbon emissions, thus reducing the risk of climate change-induced droughts in the region. The United Nations Convention to Combat Desertification (UNCCD), a global organization partnered with the Great Green Wall campaign, indicates that this growing project could remove 250 million tons of carbon from the atmosphere in efforts to improve “climate resilience in a region where temperatures are rising faster than anywhere on Earth.” These acacia trees would promote access to fertile land and water sources, and reduce the warming effects of climate change, both of which are crucial to the stability of communities in the region.
Although the completion of Great Green Wall is no longer achievable, it is important to understand the value of reforestation in restoring degraded lands and how the legacy of the Great Green Wall can live on in future projects. An article from the Smithsonian indicates that while a wall of trees would not be able to survive in a desert condition, farmers in Niger and Burkina Faso have discovered inexpensive and effective methods of regrowing plant life through “simple water harvesting techniques and protecting trees that emerged naturally on their farms.” The solution to improving soil quality in the Sahel lies not in planting forested land on the edge of the Sahara, but in implementing proper land use methods to protect trees that can expand across the region. Whether a wall or a mosaic of trees, some form of reforestation project is necessary. Given that the population of the Sahel by 2050 “could leap to 340 million, up from 30 million in 1950 and 135 million today,” according to the same Smithsonian article, the success of planting projects will play a role in shaping the well-being of future generations.
Despite its ultimate failure, projects similar to Africa’s Great Green Wall have already been achieved at a smaller scale. According to an article from Wearewater, the reforestation campaign “reflects the spirit of the Kenyan ecologist Wangari Maathai, who was the first African woman to receive the Nobel Peace Prize in 2004” and who created the Green Belt Movement, which has grown over 51 million trees in Kenya. Founded in 1977 by Maathai, the project responded to the needs of rural Kenyan women who were concerned over food security and diminishing access to water and wood. The Green Belt Movement is a testament to the success of reforestation programs that can be replicated in the Sahel and beyond. Other countries with dry conditions and fragile ecosystems, such as Fiji and Haiti, have adopted similar strategies to protect their landscapes. The vision behind the Great Green Wall reflects efficient management of land and resources, and provides a simple solution that can aid other regions in the global fight against desertification, one tree at a time.
“Acacia Tree Project.” Acacia Tree Project. N.d. http://acaciatreeproject.com.au/acacia-tree-project/. Accessed 14 Nov. 2019.
Dell’amore, Christina. “Africa-Wide ‘Great Green Wall’ to Halt Sahara’s Spread?” National Geographic, 7 Jan. 2010,
Great Green Wall. United Nations Convention to Combat Desertification, n.d., https://www.greatgreenwall.org/. Accessed 8 Nov. 2019.
Morrison, Jim. “The ‘Great Green Wall’ Didn’t Stop Desertification, but it Evolved Into Something That Might.” Smithsonian, 23 Aug. 2016.
n.a. “Why is Africa building a Great Green Wall?” BBC, 26 Sept. 2017,
Sanchez, E., McCarthy J., Gralki P. “The Great Green Wall is the Type of Utopian Project to Save the Planet.” Global Citizen. 11 Sept. 2019, https://www.globalcitizen.org/en/content/great-green-wall-explainer/. Accessed 14 Nov. 2019.
“The Great Green Wall Initiative.” United Nations Convention to Combat Desertification, n.d.,
The Green Belt Movement. The Green Belt Movement, n.d.,
http://www.greenbeltmovement.org/what-we-do/tree-planting-for-watersheds. Accessed 15 Nov. 2019.
“The Sahel, Desertification Beyond Drought.” Wearewater, 17 June 2019,
https://www.wearewater.org/en/the-sahel-desertification-beyond-drought_318262. Accessed 14 Nov. 2019.
“What is Over-Cultivation?” Greentumble, 28 June 2017, https://greentumble.com/what-is-over-cultivation/. Accessed 15 Nov. 2019.