Africa's Great Green Wall - combating climate change and desertification

Africa’s ‘Great Green Wall” (GGWSSI) is a global symbol of the anthropogenic efforts to overcome the threat of rapid climate change. It is a demonstration of how, through involving local communities, we can overcome adversity and build a sustainable future. Global cooperation is also required, as the cost of this project is set to attract around $8bn worth of funding from international organisations such as The World Bank, The UN, The UK Botanical Gardens and The African Union.


(Source: Great Green Wall)




The problem


There is currently a consensus among scientists that the Sahara Desert is no longer progressing. Although the southern edge of the desert fluctuates according to the long-term climate cycles, Dr Jonathan Davies (Head of the Global Drylands Initiative at the International Union for the Conservation of Nature), says that over the last 20 to 30 years, it has retreated north by around 200 km.


Desertification (Source: Huffington Post)


The destruction desertification has imposed on the surrounding (predominantly pastoral) communities within the region has occurred due to a collection of inextricably linked factors - climate change, over-development and unsustainable land management, thus suggesting that anthropogenic influences have been more significant in the destruction of land use and communities than the desert itself.


Therefore, Africa’s ‘Great Green Wall’ was set up in 2007 with the objective to revitalise the arid landscape and return life and work to the southern edge of the Sahara Desert - the Sahel - by planting a giant wall of trees. Once the centre of global gold trade, the Sahel is currently one of the poorest places on the planet, and at the front line of climate change. Millions of locals have already suffered from its impacts, as droughts have led to famines, and thus conflicts over the allocation of natural resources, resulting in an influx of migrants to Europe.




The Great Green Wall


This giant wall of trees is set to stretch from the east to west coast of Africa, spanning 11 countries, and will be 8000 km long and 15 km wide. So far, Senegal has made the most progress, having planted over 11 million trees, which has restored 4 million hectares of land (15% of the entire project). This is reversing desertification by returning the leaf debris to the soil, increasing the biomass stores. This consequently increases soil nutrients, providing more fertile land for further crops to grow, increasing food security.


(Source: National Geographic)


Acacia trees have been chosen to be planted in this area due to their ability to cope in arid conditions. The tree roots store water in the soil, helping to maintain the equilibrium of the water cycle within the landscape. The more trees there are, the greater the quantity of precipitation, due to increased rates of evapotranspiration from the vegetation. This new vitality and presence of moisture has recharged groundwater stores and has allowed formerly dry wells to be refilled, providing a reliable source of water, due to the storage of moisture in the soil and roots replenishing the water table.


The Great Green Wall also aims to sequester 250 million tonnes of carbon. The only issue with this is that, as young trees and saplings release more carbon than they sequester in their first few years, this results in a lag period, where carbon inputs into the atmosphere increases. However, in the long run, this is a sustainable option, as they will sequester more carbon than they release in their lifetime.




Benefits to the local community


The Great Green Wall aims to create 350,000 jobs, and to provide a reliable source of food and water for 20 million people. The scheme has already employed over 200 women in Senegal alone, to work on planting, ploughing and farming the newly revitalised land. The project is providing substantial pay, supporting families and increasing the locals' living standards, as well as reducing the price of goods, resulting in an increase in child attendance at school. The creation of jobs and improvement in food security has led to a decline in the number of emigrants seeking work abroad, reducing the threat of a brain drain in the area.


(Source: Great Green Wall)


The scheme will also enhance the beneficiary inputs from internal migration as workers are able to ‘follow the line of trees to find jobs’. The attraction of a new workforce subsequently boosts societal relations between communities, while the reduced pressure over the competition of resources and decreased hostility has promoted a friendlier and more harmonic environment, explaining why crime rates have fallen since.




Other re-greening options


There are other options rather than relying on the planting of trees, which may be more practical in some areas. For example, some of the less dry lands can be treated through the use of its ‘ecological memory’. In other words, it can rely on the lands' capacity to re-green itself if enough moisture is provided, as dormant seedlings can sprout so long as farmers protect them from overgrazing or trampling by livestock. This is known as 'farmer-managed natural regeneration', which has been proven to produce effective results at low costs. However, this method is not viable in the aridest areas, as seedlings are not able to survive underground with a severe lack of moisture.


A more feasible option is one by The Food and Agriculture Organization (FAO). The FAO is attempting to find a 'bottom-up' approach through the use of water conservation techniques and the identification of native crops. According to the FAO Forestry Officer, "it's not about planting x or y, but identifying species with the local communities and then supporting them. Sometimes you don't need to plant anything, just to assist the natural regeneration of land." Through supporting low-cost, grass-roots work, they can create the best possible conditions for reviving degraded landscapes.




Limitations and future challenges


There is evidence that planting trees may be an inefficient approach to land restoration, as a previous program in the region of Sahel found that 80% of trees died within two months, due to the lack of water and protection. However, this just highlights the need for more human employment in the scheme to protect and nurture the trees, to create a sustainable and self-sufficient structure in the future.


There is also a concern on the impact of population growth in the future, as data suggests that Africa’s population is set to more than double (from 1.1bn to 2.4bn) by 2050. This means that there will be an increase in demand for resources and land space, so unless projects like the Great Green Wall are protected by international and state governments, they may well be overturned in efforts to urbanise land for a rapidly growing population.


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