Once complete, the Great Green Wall of Africa will stretch 8000 km from Senegal to Djibouti, east-west across the entire continent of Africa, making it the largest living structure on the planet. It will also save the lives of tens of millions of people.

It was originally designed in 2007 to be a 15 km wide band of trees and vegetation. Its purpose was to stop the desertification of the Sahel region in sub-Saharan Africa. But, since then, it has now grown far beyond its initial inception.

With the help of more than 20 international organizations and governments, the project includes the ambitious goals of increasing employment, promoting renewable energy, reducing violence, ensuring food security, and many more. All of these are desperately needed, as the Sahel is considered to be among the poorest areas in the world and the hardest hit by climate change.

One of the key tools making this possible is the open source software Collect Earth. Google, the UN Food and Agriculture Organization (UNFAO), and other organizations collaborated to make this possible. It depends on a groundbreaking technique called augmented visual interpretation.

Desertification and the Sahel

Desertification is the process by which productive land becomes infertile through climate variations and poor land management. If weather patterns shift and long-term droughts ensue, coupled with human activity such as deforestation, overfarming, or allowing livestock overgrazing, once lush areas might become barren in a short time. Heavily populated areas on the edge of a desert are at a far higher risk of falling victim to desertification. This is because the area is already prone to droughts and the land is already overused.

Globally, this a major threat, especially if the climate continues to shift. According to the UN Convention to Combat Desertification (UNCCD), “12 million hectares of land are degraded through drought and the encroachment of the desert.” They estimate farmers could have grown 20 million tons of grain in an area this size.

Desertification has caused innumerable problems in the Sahel. The UN estimates 80% of the land has already been degraded. This puts tens of millions at risk of starvation, causes political instability, forces large-scale displacement of people, devastates local economies, etc. Because of this, the UN dubbed the situation in the Sahel the worst humanitarian crisis since 1945.

Desertification will force an estimated 60 million people to migrate out of the area by 2020.

Building the Wall

At first, the idea seemed simple: plant millions of trees on the southern border of the Sahara to rejuvenate the land and stop desertification. But it soon became apparent the situation was far more complicated.

For starters, how would these trees survive? Yammama, a member of the National Forest Conservation Council of Nigeria, stated “You can’t plant a tree in the desert without a water source and expect people who are struggling for water for their human needs to shoulder the extra burden of watering it.”

It soon became clear that it’s going to take much more.

The solution is a bottom-up approach. The focus is no longer on forestry. Rather it is now on water conservation, sustainable farming, reintroducing indigenous animals, developing local economies, etc. Each community determines its own course of action.

This also includes developing local industries to support these initiatives, such as Shea Butter production in Burkina Faso. This now plays a major role in sustainable development of the region.

The French Scientific Committee on Desertification explains the goal is “to ensure the planting and integrated development of economically interesting drought-tolerant plant species, water retention ponds, agricultural production systems and other income-generating activities, as well as basic social infrastructures.”

Collect Earth

A project of this size needs maps — lots and lots of detailed maps, along with the algorithms to analyze them.

Collect Earth facilitates access to several archives of satellite imagery. According to some experts, this allows “access to an unparalleled amount of information on current and past land dynamics for any location in the world.” Collect Earth is a collaboration between Google, the UNFAO, and numerous other partners,

Of course, this vast amount of information needs to be processed. Project managers need to determine the areas still in need and assess the impact of efforts already taken. The algorithms that do this use a technique called augmented visual interpretation. It is considered a drastic improvement over standard remote sensing.

It works by comparing multiple images of the same area, even with different resolutions, across different seasons and years. Moreover, the algorithms automatically create numerous graphs and indices with decades of data to be used in the analysis.

With Collect Earth and augmented visual interpretation, project managers can chart virtually every change to a piece of land. The UNFAO deemed this process an integral part of building the Great Green Wall of Africa.

Meaningful Progress

The idea of stopping the desertification of the Sahel goes back several decades, and many different solutions have been proposed. However, they all lacked the technology to bring them to fruition. Today, thanks to leaps in technology, a lot of progress has been made.

For example, local people have planted 12 million trees in Senegal. All of these are drought resistant. The local people have reclaimed 3 million hectares of land in Burkina Faso, 15 million hectares in Ethiopia, 5 million hectares in Nigeria, and 5 million hectares in Niger. The UNCCD claims the project created 20,000 jobs in Nigeria alone.

There is still a lot of work to do and many problems to overcome. But the Great Green Wall of Africa is on it’s way to realizing “its full potential as a lifeline for the Continent’s poorest people, not just to survive but to thrive once more on their ancestral lands.”

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