When a Billion Chinese Jump

northern China. The threat of drought and desertification was evident the entire length of the Great Wall, from Xinjiang in the far west to Hebei on the east coast, over 6,000 kilometers away.

China’s ancient fortifications are far more complex and environmentally significant than is commonly understood. Contrary to its singular name, the Great Wall is a series of ramparts and spurs, as well as the main trunk that snakes across northern China. In part, they are made of little more than mud. Elsewhere, they are impressive brick structures.

Construction of many of the best-known stretches began in the Qin era (221–206 BC) to keep out northern invaders. Over the following centuries, the walls were widened, lengthened, and strengthened. This massive engineering project separated two cultures and ecosystems. The settled Han agriculturalists of the southern plains wanted to protect their fields from the roaming Mongol pastoralists of the northern steppe. The wall marked the boundary between their two differing approaches to nature: fixed control versus nomadic anarchy. The cultures reflected the environments: fields and valleys against sand dunes and grassland. The wall was an attempt to keep both the climate and the enemy at bay.

It was unsuccessful on both counts. The wall was breached by both at various times in history. Mark Elvin, an environmental historian, has linked the territorial power shifts with climate change.³ In extended eras of low temperatures—such as the Little Ice Age—the Mongolian nomads were driven south to escape the cold and find new grassland and food sources. During warmer periods, the Han were able to expand their fields northward. The Great Wall was once a boundary between China and Mongolia, but the territory of the Han now stretches hundreds of kilometers farther north. The sands, however, are not so easily conquered. For decades, northern deserts have been invading southern arable land. The Great Wall was no defense. More than half of the original structure is either buried, crumbling, or torn down.⁴

Standing on the crenellated outline of the buried ramparts, I could see why William Lindesay, one of the first to walk the length of the wall, described it as “the backbone of a dinosaur.”⁵ The structure here was the broken relic that seemed to belong more to archaeology than history.

Guo and Wei were part of a mass retreat to the southeast. After centuries of land conquest and reclamation, the government was moving millions of people off fragile land that could no longer bear their weight. Pan Yue, deputy minister of the state environmental protection ministry, estimated that desertification would force the resettlement of 186 million people, about one in seven of the population.

Guo accepted that there was no choice: “We had to move because there was no water. There were times when we couldn’t grow things for ourselves so we relied on government support. But in the new place, life is better. We can grow our own food because they have diverted the Yellow River to ensure we have enough water.”⁶

We said farewell and wished the eco-refugees luck. Driving back to the main road, I saw the massive plumbing operation that made Guo and Wei’s new lives possible. The fields were flanked by concrete channels, intersected by steel pipes, and overshadowed by a giant elevated water tank. These hydroengineering works represented a fallback line of defense against the sands. But this barrier too was vulnerable because it depended on China’s most overused and abused resource: the Yellow River.

Even before the rush of modern development there were few harder-working waterways on the planet. For almost half its 5,465-kilometer length, the world’s sixth-largest river passes through desert sands, loess, and arid grasslands, nurturing 140 million people. Without the “Mother River,” as it is also called, there would be little cultivation in these dry northern plains and China as we know it would not exist. The Middle Kingdom emerged between the Great Wall and the Yellow River. Both are vital elements in the battle against entropy. Ultimately, the skeleton of Han civilization is made up of walls and dikes.

Since ancient times, emperors have tried to harness the Yellow in the fight against the desert. It has proved a fickle ally. The river bears the burden of thousands of years of environmental degradation. No other waterway in the world carries as much silt.⁷ Most of it comes from the Loess Plateau, which is a France-sized monument to erosion. The fragile soil here was formed by layers of windblown dust accumulated over two million years and held in place by trees and other vegetation. But about 5,000 years ago, soon after man began felling trees and clearing land for cultivation, the loess returned to its windblown state. Stripped of its protective layer, billions of tons of orange loess dust are carried off by the river, hence its name. One theory has it that the first mention of Huanghe (Yellow River) came in the Han era around 2,000 years ago, when the water started to discolor.

The soil erosion has turned vast expanses of Gansu, Inner Mongolia, and Shaanxi into dust bowls. Beijingers feel the consequences every spring when the city is buffeted by sandstorms. The riparian communities along the Yellow are more likely to suffer in the summer, when the combination of sediment buildup and floodwater used to make the river writhe destructively up and down the delta.⁸ Accumulated downstream, the silt raises the surface of the water far above the land, with often devastating consequences.⁹ Millions have died in the roughly 1,500 floods recorded in the Yellow’s history, hence its other nickname “China’s Sorrow.”¹⁰

Ancient rulers were judged by their ability to tap and placate this river. Even today, the giant dam at Sanmenxia is inscribed with the words “When the Yellow River is at peace, China is at peace.”¹¹ The saying is attributed to the legendary emperor Yu (c. 2100 BC), who is seen as the first in a long line of hydroengineering leaders that continues to this day.¹² The challenge they face now is not how to tame the river but how to keep it alive. With more hydro plants, thirstier cities, and ever greater demands from agriculture, the Yellow has come close to choking.¹³ Just how near became shockingly apparent in 1997, when it failed to reach the sea for 226 days. If that was not bad enough, the artery is also growing more polluted.¹⁴

An ancient folk saying predicts the Yellow will one day lose its (dis)color. The phrase Shengren chu, Huanghe qing (When a great man emerges, the Yellow River will run clear) was once an aspiration. Now, however, this seems so unlikely that the saying has become the Chinese equivalent of “And pigs might fly.” Far from becoming clearer, the spurt of industrial growth in recent years has made the river so polluted it has at various times run not just yellow but pink, green, red, black, and brown.¹⁵

From Wei’s village I drove to see the source of the worst contamination, the border between Ningxia and Inner Mongolia. The water along this stretch cooled and cleansed the thickest cluster of heavy industry I had seen in China. In return it received hot, dirty emissions that left the water so polluted that it was designated too toxic to touch.¹⁶ The buildup started near Huinong City, where the banks of the river were punctuated by smokestacks, cooling towers, fertilizer plants, plastic factories, and paper mills. More dramatic still were the scenes on the other side of the city’s bridge as we entered the industrial hellhole of Wuhai. Dust, smog, and exhaust fumes commingled so densely between the barren gray mountain slopes that it was at first hard to make out what was happening on the rocky plain between. Closer up, giant signs for the metallurgical plants and chemical refineries could be made out looming among the tangle of electricity pylons. Giant trucks rumbled out of the gates, churning up grit into the foul-smelling air as they joined an eight-lane jam of mobile tonnage. Farther along the road, smoke poured in hundreds of narrow streams from chimneys atop the long, identical rows of Lowrey-esque redbrick homes.

In just ten years, this blasted outpost had swollen from four factories to five hundred.¹⁷ Dozens more were under construction. It was aweinspiringly grim. Farther on, sand specters whispered across the road, curling patterns on the tarmac. Tumbleweed bounced madly in our path. Cyclists and pedestrians wore face masks but still grimaced in the grit and sand. On the roadside, fields gave way to dunes, and thick clouds of sand blurred visibility at ground level, though I could see blue skies above. “This is nothing,” said our driver. “In a real sandstorm the sky grows so dark that you can’t see more than twenty meters.”

Areas of land were still being farmed, but the soil was so degraded that only sunflowers could be planted. When I saw the first patch of alkaline discoloration, I thought it was a sprinkling of snow. But the pale blotches came from the fertilizer and industrial pollution that had seeped into the soil. The white earth appeared to have been sterilized.

In other areas, the pollution was black. We stopped at Wulateqianqi County, the site of a recent contamination incident. The collapse of dikes at two paper-mill containment ponds released a tidal wave of toxic sludge across farmland, two villages, and a stream that flowed into the Yellow River. Fifty-seven homes were destroyed and crops ruined.¹⁸

I arrived unannounced at the home of Yang Kuan, one of the affected farmers. He was welcoming. Word