A 5,000-mile living wall could hold back the world’s largest desert

The world’s largest desert is growing. In the last century, the Sahara Desert expanded by more than 10%, now covering an area of more than 3.3 million square miles (8.6 million square kilometers) and spanning 11 countries in North Africa.The world’s largest desert is growing. In the last century, the Sahara Desert expanded by more than 10%, now covering an area of more than 3.3 million square miles (8.6 million square kilometers) and spanning 11 countries in North Africa.