Dust bowl threatens China's future

Posted: 3 October 2002

Last year's dust storms in China were among the worst in memory, signalling a widespread deterioration of the rangeland and cropland in the country's vast northwest.

One huge storm from northern China reached the United States in April 2001 "blanketing areas from Canada to Arizona with a layer of dust", according to scientists at the US National Oceanic and Atmospheric Administration in Boulder, Colorado.

These huge dust plumes routinely travel hundreds of miles to populous cities in north-eastern China, including Beijing, obscuring the sun, reducing visibility, slowing traffic, and closing airports. News reports typically attribute the dust storms to the drought of the last three years, but the drought is simply bringing a fast-deteriorating situation into focus.

Human pressure on the land in north-western China is excessive, according to Lester Brown's Earth Policy Institute. There are too many people, too many cattle and sheep, and too many ploughs. Feeding 1.3 billion people, a population nearly five times that of the United States, is not an easy matter.

Millions of Chinese farmers have been warned to "save every drop of water" as drought spreads across the country. Experts at the national headquarters for flood prevention and drought control say it is "the most serious and widespread since 1990", affecting more than 20 provinces.

Rainfall in the spring was down by between 30 and 90 per cent in many parts of China. Sand-laden winds from the expanding inland deserts have badly affected the North. Wang Shaowu, a climatologist at Beijing University, says summer drought in North China should now be regarded as normal. "In fact, the drought may be just beginning," he said. The people of China should be "prepared psychologically" for a new era of drought.

In addition to local pressures on resources, a decision in Beijing in 1994 to require that all cropland used for construction be offset by land reclaimed elsewhere has helped create the ecological disaster that is now unfolding.

Offset policy

In an article in Land Use Policy, Chinese geographers Hong Yang and Xiubin Li describe the environmental effects of this offset policy. The fast-growing coastal provinces, such as Guangdong, Shandong, Zhejiang, and Jiangsu, which are losing cropland to urban expansion and industrial construction, are paying other provinces to plough new land to offset their losses. This provided an initial economic windfall for provinces in the northwest, such as Inner Mongolia (which led the way with a 22-per cent cropland expansion), Gansu, Qinghai, Ningxia, and Xinjiang.

As the north-western provinces, already suffering from overploughing and overgrazing, ploughed ever more marginal land, wind erosion intensified. Now accelerating wind erosion of soil and the resulting land abandonment are forcing people to migrate eastward, not unlike the US westward migration from the southern Great Plains to California during the Dust Bowl years of the 1930s.

In the New York Times, Beijing Bureau Chief Erik Eckholm writes that "the rising sands are part of a new desert forming here on the eastern edge of the Qinghai-Tibet Plateau, a legendary stretch once known for grass reaching as high as a horse's belly and home for centuries to ethnic Tibetan herders." Official estimates show 2,330 square kilometres of land going to desert each year. An area several times as large is suffering a decline in productivity as it is degraded by overuse.

Planting trees

In addition to the direct damage from overploughing and overgrazing, the northern half of China is literally drying out as rainfall declines and aquifers are depleted by overpumping. Water tables are falling almost everywhere, gradually altering the region's hydrology. As water tables fall, springs dry up, streams no longer flow, lakes disappear, and rivers run dry.

Deforestation in southern and eastern China is reducing the moisture transported inland from the South China Sea, the East China Sea, and the Yellow Sea, writes Wang Hongchang, a Fellow at the Chinese Academy of Social Sciences.

Where land is forested, the water is held and evaporates to be carried further inland. When tree cover is removed, the initial rainfall from the inland-moving, moisture-laden air simply runs off and returns to the sea. As this recycling of rainfall inland is weakened by deforestation, rainfall in the interior is declining.

Reversing this degradation means stabilizing population and planting trees everywhere possible to help recycle rainfall inland. It means converting highly erodible cropland back to grassland or woodland, reducing the livestock population, and planting tree shelter belts across the windswept areas of cropland, as US farmers did to end dust storms in the 1930s.