Africa’s Great Green Wall project began as an ambitious plan to build a 15-kilometre-wide band of trees across the north of Africa. The African Union launched the project in 2007 with plans for the trees to extend for 6,000 kilometres through 11 countries in the Sahel, restoring 100 million hectares of land from Senegal to Djibouti and Ethiopia. Its main aim was to prevent the Sahara Desert from advancing. But the Great Green Wall’s also been billed as a solution to climate change, poverty, and even extremism.

Senegal has been one of the most active countries implementing the Great Green Wall initiative, despite being among the smallest. It has targeted 817,500 hectares of land for restoration. Environmental researchers Annah Lake Zhu and Amadou Ndiaye were part of a team who looked at satellite images of some of Senegal’s section of the wall and found that only one out of 36 planted areas analysed was more green than it would have been naturally. The project is not an actual wall of trees but rather a mosaic of rehabilitated land. But increased greenery should still be visible from satellite imagery. They also found that financial pledges were often left unmet, money for the wall didn’t make it to ground level and new trees had low survival rates.

How much money was pledged and where has it gone?

So far, more than US$20 billion has been pledged, including large sums of money like the US$4 billion pledged at the Paris climate conference in 2015 and the US$14.3 billion committed by the 2021 One Planet Summit.

Read more: Africa's Great Green Wall plan needs a rethink

Pledges at global summits attract media headlines, but do not always materialise. Often only a small fraction of pledged funding reaches target countries, and an even smaller fraction makes it to the ground level.

For example, a 2020 assessment of the Great Green Wall’s funding indicated that Great Green Wall countries reported receiving a total of only US$149 million between 2011 and 2019.

Of the 2021 pledge of US$14.3 billion, by March 2023 only US$2.5 billion had been disbursed.

This gap exists for several reasons, perhaps the biggest being simply bureaucracy. Each project in the Great Green Wall that receives funding from global financiers like the World Bank, Global Environmental Facility or African Development Bank must go through rigorous project preparation and approval phases. Funds are not transferred instantly – some countries have a designated agency to receive the funds, others don’t. Much of the funding is sent to development projects that align with the Great Green Wall’s goals, but aren’t necessarily directly used for planting trees.

Even if pledged funds could instantly show up in recipient countries’ accounts, governments often lack the capacity to absorb and distribute large sums at the local level. Budget allocation constraints within countries may also lead funds to be reassigned to other sectors, such as infrastructure, education and health.

Read more: Climate adaptation funds are not reaching frontline communities: what needs to be done about it

On top of all this, many Great Green Wall countries – Burkina Faso, Mali, Niger – are now governed by regimes that are no longer western-friendly. Most long-term environment and development aid has been halted and rural implementation sites have been destabilised by insecurity.

What should be visible on the ground by now?

After nearly two decades, even taking into account that not all the money pledged has materialised, results should be visible.

However, the Great Green Wall project doesn’t use satellite photos to measure progress. Instead, it reports on the number of trees planted or area of land set aside for natural regeneration. This land is generally included toward the goal of 100 million hectares of restored land, even if the trees never grow.

The European and African-led Great Green Wall Observatory and the Great Green Wall Big Data Facilitator, run by the Chinese Academy of Sciences in partnership with participating African countries, are moving to satellite monitoring of plant growth across the region generally. But it will be a while before these platforms are able to systematically measure the impact of planting at the site level.

What does the Great Green Wall look like in Senegal today?

We visited Great Green Wall sites in Senegal and interviewed project personnel and community members where reforestation activities occurred. Our team also looked at satellite photos of 36 plots covering 18,090 hectares of the Great Green Wall’s Senegal target area of about 817,500 hectares.

Our research found that the Great Green Wall generates jobs in new tree nurseries, planting, and work as guardians at reforestation sites. Harvesting of non-timber forest products (gum Arabic and desert dates) is another benefit of the Great Green Wall, which also provides social services like healthcare and constructing firebreaks.

These benefits are tangible: jobs in remote areas where there is very little work. But the jobs are often short-lived – limited mostly to the planting season or when a new reforestation plot is being established.

Read more: How countries alongside the Sahara can restore productive land faster

Ecologically, the impact is much less clear. Our satellite imagery analysis of 36 reforestation plots in Senegal showed that only two were much greener since the wall was first established. And only one of these was more green than it would have been naturally.

This may be because the new trees are not irrigated. Even though drought resistant species are planted, many trees die off if the rainy season is mild. Trees are also trampled or eaten by cattle when fencing is not properly maintained.

Read more: Senegal's remote Bassari people talk about climate change, and how their local knowledge is key to coping strategies

By examining the specific areas where restoration work has been performed, and adjusting for expected greening from rainfall, our study found that, overall, the Great Green Wall has had hardly any ecological impact in Senegal.

What needs to happen next?

Too often we hear about the money a project needs to achieve its goals – like the UN’s figure of US$33 billion needed for the Great Green Wall. This is a fiction. Huge projects like these need more than money. They need reliable ways to get the money to the grassroots level. This must be addressed.

Project assessments must also stop using activities alone (like number of trees planted) as measures of success. Rather, it is the outcomes of these activities – increased greening and reduced land degradation – that show success.

Powerful digital and remote monitoring tools are available to monitor the Great Green Wall. These didn’t exist when the project started. Our recommendation is to use them: set targets for increased vegetation along the wall’s pathway, monitor project impacts remotely, and reward success generously. This is the model for the future. It moves beyond symbolic pledges to focus on actual changes on the ground.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Annah Lake Zhu, Wageningen University and Amadou Ndiaye, Université Amadou Mahtar MBOW de Dakar

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Annah Lake Zhu receives funding from the Dutch Research Council (NWO).

Amadou Ndiaye works at Amadou Mahtar Mbow university.