Africa’s Great Green Wall

Africa does not come to mind when one thinks of audacious public works projects. But the continent’s growing wealth and political stability, combined with the pressing challenges of climate change and environmental degradation, is driving its leaders to come together and concentrate their efforts into forging bold new solutions.

Among them is the Great Green Wall, an incredible idea to create a wall of vegetation across the width of the Sahara to stave off rapid desertification and improve agricultural output (which most Africans depend on for survival). It would be around 4,000 kilometers in total, making it the largest “living structure” in the world, three times the size of the Great Barrier Reef.

As The Economist explains, the idea has its roots (pardon the pun) in the 1950s, when a British environmental scientist named Richard St. Barbe Baker proposed planting a swathe of trees across the southern Sahara. This would block the wind and sand that move southward from the desert while improving agricultural yields by binding sediment together and adding nutrients.

Unsurprisingly, the sheer scale of the idea, not to mention the fact that most of Africa remained colonized, gave it little traction until about a decade ago.

In 2005, Olusegun Obasanjo, then president of Nigeria, revisited Mr Baker’s proposition, seeing in it an answer to some of the social, economic and environmental problems afflicting the Sahel-Sahara region. An estimated 83% of rural sub-Saharan Africans are dependent on the region’s land for their livelihoods, but 40% of it is degraded—worn away by soil erosion, human activity and scorching temperatures—leaving much of it unfit for use.

In 2007, Mr Obasanjo gained the support of the African Union. The Great Green Wall Initiative was launched the same year. Today some 21 African countries are involved in the project, which has grown in scope. Trees have been planted, but building a wall of them is no longer the priority. Instead, the wall of trees has become a vehicle for a wider goal: countries in the region working together to tackle climate change, food security and economic growth. Recent projects include abating soil erosion and improving water management in Nigeria, agribusiness development in Senegal and forestry management in Mali. Each country takes it own approach to achieving shared goals. Some focus on community planning through education, while others are expanding investment in technology and training for farmers. Since the project started, 15m hectares of land have been restored in Ethiopia and 20,000 jobs have been created in Nigeria.

The Economist article is from 2016, and I have heard little else about the project since (although an official website remains up to date, suggesting that it is still in the planning stages). The most recent article I came across, dated 2017 in The Conversation, takes a more skeptical view of the idea, and not just for practical reasons of feasibility:

Critics argue that a desert is a healthy, natural ecosystem that shouldn’t be thought of as a disease. Nor, they argue, is it spreading like a disease. In fact, by the end of the 1990s, the idea of encroaching deserts had become difficult to defend against scientific evidence that climate variability was to blame.

Critics have also pointed out that the vision of a barrier is counter-productive to the development objective as it draws attention to the perimeter of the land rather than to the land itself. To boost food security and support local communities it is better to focus on the wide field rather than its narrow edge. The development objective is important – an estimated 232 million people live in the general area of the Great Green Wall.

This led to the clarified vision keeping the wall in name, but it has been bent almost beyond recognition.

The wall is no longer seen as a narrow band of trees along the southern edge of the Sahara. The vision is now to surround the Sahara with a wide belt of vegetation – trees and bushes greening and protecting an agricultural landscape. The new vision engages all the countries surrounding it, including Algeria and others in North Africa, not just the 11 original sub-Saharan countries of the Sahel.

The article points out that even if it were an unambiguously good idea, the sheer size of it, plus the amount of upkeep needed, would require too many resources and many more decades to see fruition. Better approaches may exist:

Many people assume that the wall can only be built only by planting trees. But tree planting is not always needed. Some of the less dry lands can be treated by techniques that rely on the capacity of the land to regreen itself – its ecological memory.

Floods and animals move seeds to places where they can sprout and root systems of former trees are sometimes capable of producing new shoots. Sprouting roots could live as the roots are already established – unlike newly planted seedlings. These could rapidly re-green a landscape, reducing the need for tree planting, as long as farmers protect them from fire and cattle.

This technique – known as farmer-managed natural regeneration – has proven to produce good results at low cost in areas where the ecological memory is sufficient for sprouts to come up by themselves and where farmers have the right to use the trees once they get big. The potential to scale it up is significant.

But farmer-managed natural regeneration will not work everywhere. Other methods are needed too, such as digging half-moons (to capture water) and planting seedlings. Doing a better job of applying the right method to the right place may be the quickest and most feasible way to speed the making of the Great Green Wall.

What are your thoughts?


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