Unlike the Great Wall of China, a 5,000-mile fortification dating back to the 7th century BC that separates northern China from the Mongolian steppe, the Great Green Wall of China—otherwise known as the Three-North Shelter Forest Program—is the biggest tree planting project on the planet. Its goal is to create a 2,800-mile long green belt to hold back the quickly expanding Gobi Desert and sequester millions of tons of carbon dioxide in the process. If all goes according to plan, the completion of the Green Wall by 2050 will increase forest cover across China from five to 15 percent overall.

The Chinese government first conceived of the Green Wall project in the late 1970s to combat desertification along the country’s vast northwest rim. Soon thereafter, China’s top legislative body passed a resolution requiring every citizen over the age of 11 to plant at least three Poplar, Eucalyptus, Larch and other saplings every year to reinforce official reforestation efforts.

But despite progress—according to the United Nations’ most recent Global Forest Resources Assessment, China increased its overall forest cover by 11,500 square miles (an area the size of Massachusetts) between 2000 and 2010, with ordinary citizens alone planting upwards of 60 billion trees—the situation is only getting worse. Analysts think China loses just as many square miles of grasslands and farms to desertification every year, so reforestation has proven to be an uphill battle. The encroaching Gobi has swallowed up entire villages and small cities and continues to cause air pollution problems in Beijing and elsewhere while racking up some $50 billion a year in economic losses. And tens of millions of environmental refugees are looking for new homes in other parts of China and beyond in what makes America’s Dust Bowl of the 1930s look trivial in comparison.

“The desertification of north and western China is arguably the most under-reported environmental crisis facing China today and is little understood outside the circles of NGOs [non-governmental organizations] and groups of scientists who are desperately fighting against it,” reports Sean Gallagher, an activist with Greenpeace. While climate change is certainly a big factor, Gallagher adds that overgrazing, water mismanagement, outdated agricultural methods and the swelling of human populations are also contributing to this wholesale conversion of the region’s once arable and habitable landscapes into sand dunes. “In China, approximately 20 percent of land is now classified as desert or arid, and desertification is adversely affecting the lives of over 400 million people in China alone.”

More recently, the Green Wall project has taken on additional importance for its potential as a “carbon sink” to store greenhouse gases that would otherwise find their way into the atmosphere and exacerbate global warming. But critics point out that it’s hard to quantify just how much carbon the Green Wall can store, and that plantations of fast-growing non-native trees going in as part of the project don’t store as much carbon as more diverse, naturally occurring native forests.

Regardless, the Chinese government is already talking up the Great Green Wall as key weapon in its arsenal to fight global warming and as proof to the rest of the world that China is taking strong steps to mitigate carbon emissions. With completion of the Great Green Wall still 35 years out, only time will tell how effective it will be as a solution for some of China’s (and the world’s) most vexing environmental problems.