After decades of human activities and overgrazing, desertification has accelerated at an alarming speed in China, resulting in sandstorms, flooding and drought. The economic repercussions are potentially affecting more than 400 million people.

In the past, Chinese kingdoms and empires erected the Great Wall to prevent steppe nomads from invading from the north. Now, the government is planting a whole new kind of wall to protect from encroaching deserts.