ACROSS the length and breadth of China dust storms are an annual event 鈥� a clear sign that spring has sprung. And boy, does it make an entrance. Between January and May each year, strong winds blowing to the south-east lift millions of tonnes of fine soil from the plains of Inner Mongolia and north-western China. So much soil has been lost that what was once lush grassland has turned into a dustbowl. Much of the lost soil smothers other parts of the country, while the rest is wafted high into the air to be carried across the world.
Either way, the results can be catastrophic. Dust storms cause destruction on the scale of a serious earthquake. They can kill people and livestock, destroy crops, and force whole communities to abandon their homes. With dust-laden winds blowing at up to 100 kilometres per hour, people in large parts of China stay indoors with the windows firmly shut for weeks on end during spring. When the storms have passed, they emerge to find trails of dust beaten into the windowpanes. In Korea and Japan, dust blown from China has closed airports, turned the rain brown and choked rivers and lakes with algal blooms. It has even found its way across the Pacific to hang as an orange haze over Colorado. China鈥檚 dustbowl is becoming a global problem.
But the Chinese government has not been standing idly by. In the 1970s it began what it claims is the biggest ecological project in the world. Under this programme, which has become known as the 鈥済reen great wall鈥�, trees have been planted on an unprecedented scale to create a barrier that will halt the dust in its tracks. But doubts are starting to creep in that even the green great wall might not be able to defeat the dust. So this year, China has joined forces with its Asian neighbours to mount an alternative attack. Will this at last be enough to clear the air?
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鈥淭he sky was yellow, a little bit black and red. It was quite difficult to breathe. Visibility was reduced 鈥� I couldn鈥檛 see my dormitory building although I knew it was 50 metres away. People went out for 5 minutes, and they looked like they had been at a construction site. The day was dark and suffocating but a magnificent sight鈥�
The equation behind the disaster is simple. Strong winds plus bare soil equals dust storms that carry soil particles thousands of kilometres. As the winds slow, heavier particles drop out of the sky, leaving behind an airborne soup of ever finer dust. By the time a storm reaches Beijing, a couple of thousand kilometres from the Mongolian plains, the remaining particles are fine enough to stay suspended in still, dry air. The stuff can hang there for days.
Dust storms are nothing new in northern China. Once they were a harmless part of the global nutrient cycle, in which dust from the Sahara, for example, provides nutrients to the South American rainforest canopy. In a similar way, Chinese dust improves plankton productivity in the ocean around Hawaii. 鈥淭his process has been happening for at least 2.6 million years, probably much longer,鈥� says Edward Derbyshire, honorary professor at the Gansu Academy of Sciences, south-west of Beijing. 鈥淲hat has happened in the past few decades is that mankind has put his foot in it, so to speak, and accelerated a natural process.鈥�
In China, decades of overgrazing and deforestation, combined with drought and over-exploitation of water resources for agriculture, has transformed vast areas of grassland into dusty desert. And just as American and Australian farmers discovered in the 1930s, there is only so much a desert ecosystem can take before it degenerates into a dustbowl. It took three decades to correct the damage in those countries, using a mixture of education, improved land management and investment. Now it is China鈥檚 turn, and with almost a third of the country鈥檚 land degraded to the point of desertification, the scale of the project is ambitious to say the least.
China is attacking the problem on two fronts. The first is to slow the dust-laden wind with strategically placed windbreaks to prevent key installations such as roads and railways being smothered. The second focuses on keeping dust bound up in the soil, mainly with drought-tolerant plants. The green great wall, officially known as the Three-North Shelterbelt Development Programme, was designed to tick both boxes and protect farmland to boot. It was set up in 1978, and aims to cover more than 35 million hectares of land with trees by 2050. It is already almost halfway to its target, with most of the planting on the margins of the Taklimakan desert in north-western China, in Inner Mongolia and in other provinces in the north and north-east (see Map). Over huge areas, what was once farmland has been converted to forest and shelter belts. Locals have been encouraged to do their bit by planting several trees each year 鈥� preferably species that provide fruit, fodder and wood that can be grown sustainably for timber or fuel. That way, trees become a valuable rural commodity.
But while the green great wall project earns full marks for effort, there are those both in China and abroad who consider it a waste of resources at best, and possibly in danger of doing more harm than good. 鈥淭he State Forest Administration, who have the mandate for desertification control, have persuaded the central government that tree planting is the answer. I have little faith in it,鈥� says Victor Squires, dryland management consultant and project manager at the Asian Development Bank. 鈥淧recious groundwater is being pumped to grow trees in the desert where no tree has ever grown before. This will cause desertification and rob the poverty-stricken farmers of water that they need for subsistence cropping.鈥� And in the spring, the trees are leafless anyway. 鈥淏are stems do little to break the wind. They are planted in rows and the corridors between are swept bare by the venturi [funnelling] effect generated by the layout.鈥�
As that message filters through, the Chinese government has begun to put more emphasis on other measures, such as planting grasses and shrubs to fix the sands and dusty soil, and ways to meet the urgent need to conserve water. It has also triggered a range of new projects, some of them highly controversial.
One of the schemes that has attracted most criticism is already under way in Inner Mongolia. The plan is to help grasslands recover by moving 3000 nomadic families off the lands where they have traditionally grazed their goats. The scheme pays these families to swap their vast herds of goats for just a few cattle, and houses them in villages where the cattle will graze a drastically reduced area of land. For people who have lived for generations as nomadic herders, the transition to a settled life is far from easy, and amounts to an infringement of their human rights, critics say. They also argue that the nomads are paying the price for overgrazing that was ultimately caused by unrealistic government targets for agricultural production in the region.
In the northern region of Ningxia, experiments aimed at keeping dust on the ground are under way, using straw mats, for example, and more controversially, chemical 鈥済lues鈥� made from asphalt or polyacrylamide that form a solid crust on the soil surface. In the Xinjiang region of north-west China, the falling water table is being tackled with water conservation measures. Another programme, known as Grain for Green, offers cash and grain subsidies to farmers who plant trees.
Despite these efforts, there has been growing scepticism over their effectiveness. Rumblings of discontent from China鈥檚 neighbours led in 2003 to an international project funded by the Asian Development Bank, the UN and the Global Environment Facility. The project brought together consultants and the governments of China, Mongolia, Japan and Korea, and aimed to create a multinational plan to tackle the dust. Ministers met in Korea at the end of March to approve the plan, and the final version has just been published. The first phase is expected to be implemented next year, and this time tree planting will play no more than a supporting role.
Led by Squires, the project team has identified four target areas in China, four in Mongolia and one straddling the border. In each, measures will be tailored to the specific type of landscape. Dry grassland areas will be reseeded and fenced off, and fodder plantations will be planted to feed livestock that formerly grazed there. In more mountainous regions, Chinese pine will be planted, and solar and wind energy will replace wood-burning as a source of energy. To compensate for lost farmland, new, more environmentally-friendly industries are proposed, including dairy farming, growing ginseng, selling sustainably grown willow cane to the paper industry, and ecotourism. In the cross-border project, a high-tech nursery and training centre will support efforts to reinstate the grasslands, and a sustainable forest irrigated with waste water will provide a model for future shelter-belt efforts.
Some sticking points remain, however. One condition for funding is that the governments involved must find a way to eliminate the duplication and conflicting legislation that have hindered past efforts to tackle the problem. For example, while one branch of the Chinese government is promoting conservation measures in the dust-prone lands, another may be setting targets for agricultural production that are almost guaranteed to make the problem worse. Some Chinese provinces appear to be struggling to find a way to prevent different agencies working against each other. There is also disagreement over the size of the plots for the experimental phase of the programme. But Derbyshire thinks it is important to work towards cooperation between agencies and governments. 鈥淚ntegration is the key,鈥� he says.
The priority now is to make sure China can feed its growing population without choking on the consequences. Despite the magnitude of the task, Squires remains optimistic. 鈥淐an China fix the problem? The answer is a guarded yes.鈥� Get people to work together, and dump some of the ideologically driven but impractical approaches, he says. 鈥淭hat is the long-term solution.鈥� But the benefits will take decades rather than years to appear. Until then, the residents of Beijing will have to close their windows when the spring storms blow in, and wait for summer.
Dustbowl Earth
SOME think that today鈥檚 catastrophic dust storms in China are just a phase in a much bigger, natural cycle. According to Hang Gao, a graduate student who is studying the problem at the University of Oxford, the earliest known dust storm was recorded in 300 BC. There are also accounts from the time of the Han dynasty (206 BC to AD 220). Since then, there have been five particularly bad periods for dust storms: 1060 to 1090, 1160 to 1270, 1470 to 1560, 1610 to 1700, and 1820 to 1890, according to the Chinese Meteorological Administration.
So is China merely in the grip of another dusty spell? The picture is far from clear. In the north of the country, there were fewer dust storms in the 1990s than in the 1950s and 1960s. But since 1999, the number of dust storms and their intensity has increased, and they have begun earlier and affected larger areas.
Whatever the story in China, the amount of airborne dust globally is on the rise, and estimates suggest that the amount of soil blown away every year adds up to about 3 billion tonnes.
Advances in satellite imaging have made it possible to identify the world鈥檚 biggest dust sources and track their dust as it blows across the globe. Andrew Goudie of the University of Oxford has analysed readings from two of the latest satellite-based instruments, the Total Ozone Mapping Spectrometer and the Moderate Resolution Imaging Spectroradiometer. 鈥淭hey give a daily picture of where dust is coming from and going to,鈥� he says. 鈥淲e鈥檝e analysed that data since 1979 so we now have a good handle on where the hotspots are in the world for dust generation.鈥� The worst culprit is the Bodele depression in Chad, north Africa, with the western Sahara desert and the Taklimakan desert in central Asia coming in close behind.
Experience in the US and Australia has shown that the dustbowls caused by land degradation can be turned back into fertile land given enough time, money, the right kind of effort and, crucially, a cooperative climate. But with most of the planet鈥檚 major dust sources in the developing world, the question now is, who will pay to put it right?
