While the president is busy trying to build a wall at the southern US border, locals, environmentalists, and scientists from more than 20 African nations are building a wall of trees at the southern edge of the Sahara Desert to fight the effects of climate change. The tree-planting project, which has been dubbed The Great Green Wall of Africa, stretches across 6,000 miles of terrain. This region was a lush oasis of greenery and foliage back in the 1970s, but the combined forces of population growth, unsustainable land management, and climate change turned the area into a barren swath of land. The initiative started in 2007 and it is far from being complete, but it has already dramatically impacted countries in the region, restoring millions of acres of degraded land in countries like Nigeria and Ethiopia. The restoration process is simple: canopies increase the humidity of the environment, and roots hold water in the soil. Increased water leads to reversed desertification, allowing locals to grow their food once more, refilling previously empty wells with drinking water while slowing down migration. Backed by a host of international governments and conservation groups from around the world, the completed wall will be the largest living structure on the planet, three times the size of the Great Barrier Reef.