Walls are traditionally controversial. For the most part, their goal is to separate people, keeping the ones you don't want from mingling with the ones you do.

But a massive wall being built in Africa is motivating people from 20 countries to join forces for a large-scale project for the common good. The Great Green Wall is an ambitious plan to grow a thicket of drought-resistant trees across about 6,000 miles (8,000 kilometers) of land at the southern edge of the Sahara desert, a region known as the Sahel. It runs the width of the continent, from the Atlantic Ocean to the Red Sea.

The area was once green and mostly covered in grassland and savanna. But lingering droughts have changed its makeup. Now, "More than anywhere else on Earth, the Sahel is on the frontline of climate change and millions of locals are already facing its devastating impact," according to the project website.

The area is dry and barren and, as a result, there's a lack of food and water, and increased migration as people look for better places to live, and conflicts erupt over dwindling natural resources.

After years of working on a solution, leaders from 11 African countries signed on to the initiative in 2007. Today, There are more than 20 countries involved.

The Great Green Wall covers 780 million hectares of arid and semi-arid land, and the area is home to 232 million people, according to the Food and Agricultural Organization of the United Nations.

Everyone makes an impact

elder with child working on Great Green Wall Men, women and children have all been working on building the wall. (Photo: Great Green Wall)

Men and women of all ages are joined by children to plant mostly drought-resistant acacia trees, as well as gardens filled with vegetables and fruits. Just over a decade into the project, it's about 15 percent complete.

As the project greens up the arid landscape, the trees are having an impact on more than land degradation and desertification in the region. Not only is life coming back to the land, but the millions of people who live there have found food and water security, increased well-being, more jobs (even boosting gender equality as women also have found work) and a reason to stay.

Research institutions, grassroots organizations, scientists and even tourists have visited the area as the project unfolds. As Atlas Obscura points out, this influx, "has also brought attention and resources to a neglected region in which aid is scarce and doctors are not readily available for the needy populations."

Changing the future

Great Green Wall When finished, the Great Green Wall will be three times the size of the Great Barrier Reef. As the group's symbol implies, the wall runs from coast to coast. (Photo: Great Green Wall)

Once it is finished, the Great Green Wall should be the largest living structure on the planet, three times the size of the Great Barrier Reef.

"There are many world wonders, but the Great Green Wall will be unique and everyone can be a part of its history," said Dr. Dlamini Zuma, chairperson of the African Union Commission, in a statement on the project's website. "Together, we can change the future of African communities in the Sahel."

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.

Why Africa is building a Great Green Wall
More than 20 countries are working together to build the Great Green Wall, planting trees and saving water, food and lives.