In may not be surprising that China, home to so many other superlatives, also faces desertification on a grand scale. According to China’s State Forestry Administration, over 27 percent of the country now suffers from desertification – more than 1,000,000 square miles, or about one-third of the continental United States – impacting the lives of more than 400 million people.

At the Desert’s Edge, a new short documentary from the Asia Society and filmmaker Jonah Kessel, explains these challenges and efforts to combat it in Kulun Qi, a dry area in northeastern Inner Mongolia.

The film focuses on the perspectives of small, local units of families and farmers. “When my mother was young,” Ma Enqi, a shopkeeper in the film says, “the desert wasn’t so expansive. The land around here all used to be farmland when she was still in her 30s.” Though migration has been the “solution” for desertification in many parts of China, Ma and his family seem to be trapped on the land they have lived for decades. And they have witnessed the desert grows wider and wider.

“You can’t escape it, whether you’re afraid or not,” Maona Mula, a local farmer, says with a bitter smile gazing at the land covered with sand, rocks, and wood chips. His livelihood comes from “some crops, some firewood,” cows, and the pigs behind him. “When you are poor, you can’t do anything else,” he says.

Desertification is a perfect illustration of the water-food nexus increasingly challenging people in China and elsewhere around the world. Without water, farmers cannot grow crops. Yet over-exploitation of land, via overgrazing or overuse of fertilizer, for example, decreases the quality and accessibility of water and soil, making land more vulnerable to drying. Choke Point: China – a joint initiative between the Wilson Center’s China Environment Forum and Circle of Blue – highlights how the growing water footprint of coal power development constrains agriculture and exacerbates desertification. But the challenge does not stop at China’s doorstep; according to the UN, desertification and land degradation affects 168 countries and costs $490 billion a year.

Where water is still reasonably accessible, as in the case of Kulun Qi, one way to combat desertification and drought is tree planting. Trees help hold moisture and prevent soil erosion. In the simple words of Xuan Yuquan, a local resident, “if you plant trees, the crops will survive. If there aren’t any trees, the crops will die.”

At the Desert’s Edge highlights the efforts of Shanghai Roots and Shoots, part of the global Roots and Shoots NGO created by primatologist Jane Goodall. Since 2007, volunteers from the megacity of Shanghai have come to desolate Inner Mongolia to plant trees with local farmers. The organization asks farmers to monitor and maintain those trees, engages local students for environmental education, and employs a full-time forestry manager to evaluate and ensure tree growth. To date, they have planted more than 1.2 million trees and are on their way to their target of two million. And the results are visible, as testified by a forester and a longtime resident in the film.

Apart from civil society’s efforts, the central government is also working on an environmental engineering program of unprecedented scale. The Three-North Shelter Forest Program, also known as the “Green Great Wall,” is a 2,800-mile network of forest belts covering all the major deserts and sandy lands in northwest China and over 40 percent of the country’s entire territory. The project is designed to serve as a windbreak to stop sandstorms, halt the expansion of desertification, and to restore land to a productive and sustainable state. To date, the project has re-planted and protected about 10,000 square miles of forest, achieving more than two-thirds of its goal of 14,500 square miles by 2050.

Still, the gains made are fragile. Winter storms can destroy vulnerable new trees. In many places, groundwater availability could actually decrease as trees soak up more. And herders claim that protecting grasslands from overgrazing could also drive certain animal species to extinction.

As we join together for 2013’s World Day to Combat Desertification, we need to realize that this is a long battle on a massive scale. It will take many trees and other much larger behavior changes in communities, businesses, and governments around the world to protect our future from drying up.