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The green wall of China PDF พิมพ์
เขียนโดย Evan Ratliff   
Friday, 16 November 2007

November 15, 2007 By Evan Ratliff

The Chinese call it "yellow dragon." Koreans, "the fifth season." Each spring, the dust from 's northern deserts is swept up by the wind and whipped eastward, blasting into Beijing. A choking blanket of particles coats houses, cars, and people, and the city's hospitals become flooded with patients suffering from respiratory ailments.

The dust clogs machinery, shutters airports, and destroys crops, forcing thousands of rural Chinese off their lands. Clouds of it blow throughout Asia, carrying pollution and potentially infectious disease. In , the government recently considered declaring the dust storms a natural disaster. The furies are fed by desertification: Overgrazing, deforestation, and drought convert arid land to desert, creating a layer of mobile topsoil.

This combination of forces is expanding the Gobi desert by about 950 square miles per year - an area two-thirds the size of Rhode Island. Now, with the dunes within 150 miles of 's capital city, and the 2008 Olympics on the way, Beijing officials have initiated a massive campaign to attack the problem.

The plan is known as the Green Great Wall - a 2,800-mile network of forest belts designed to stop the sands. Chinese scientists from the Ministry of Forestry believe the trees can serve as a windbreak and halt the advancing desert. In a recent report to the United Nations, Chinese officials predicted that the effort will "terminate expansion of new desertification caused by human factors" within a decade. By 2050, they claim, much of the arid land can be restored to a productive and sustainable state.

Possibly the largest proposed ecological project in history, the new Great Wall calls for planting more than 9 million acres of forest at a cost of up to $8 billion. The project began last year as the fourth phase of an afforestation program launched in 1978. By 2010, the green belts are expected to stretch from outer Beijing through Inner Mongolia. To build the wall, the government has launched a two-pronged plan: Use aerial seeding to cover wide swaths of land where the soil is less arid, and pay farmers to plant trees and shrubs in areas that require closer attention. A $1.2 billion oversight system, consisting of mapping and land-surveillance databases, will be implemented. The government has also hammered out a dust-monitoring network with and .

The wall itself will be made up of an outer belt - ranging from 775 to 1,765 feet wide - with a sand fence along the perimeter. Inside, low-lying, sand-tolerant vegetation, arranged in optimized checkerboard patterns, will create an artificial ecosystem to stabilize the dunes. A 6-foot-wide gravel platform will hold sand down and encourage a soil crust to form. The government has also funded research to explore the use of genetically engineered plants, chemical dune stabilization, grass strains bred in space, and even farming techniques that will allow rice to grow in sandy soil.

Can an expansive row of trees and some strategically placed grass really stave off an encroaching desert? It worked before. In 1935, overgrazing and drought caused 850 million tons of topsoil to blow off the ' southern Plains, leaving 4 million acres barren and creating the Dust Bowl. To address the problem, the newly formed Soil Conservation Service introduced the Shelterbelt Project - a 100-mile-wide strip of native trees bisecting the country from to Texas. In a few years, it helped to reduce the amount of airborne soil by 60 percent.

But in , the question remains as to whether the area targeted by the wall is just too arid to support trees. And even if the trees do take root, they'll soak up massive amounts of groundwater, which could worsen the problem. "You may improve one part of the landscape," says Hong Jiang, a geography professor at the University of Wisconsin, "but you can't hold back the degradation."

Ultimately, many Western scientists fear that the Green Great Wall is an expensive band-aid on a centuries-old wound. Or worse, propaganda. Either way, Dee Williams, a US Department of Interior anthropologist who has cataloged the failure of past anti-desertification efforts in , argues that the country must move beyond micro-level tech fixes and embrace political solutions. The government needs to foster positive behavior - pay farmers to reduce livestock numbers, raise water prices to encourage conservation, and temporarily relocate locals away from arid areas to allow recovery. The last hope, says Williams, is that the choking dust will force the government to act. "Maybe it takes a crisis to precipitate the kind of creative thinking the Chinese are capable of," he says.

With the dust storms intensifying, the success or failure of the wall will have an effect beyond 's backyard. Last year, Pacific winds blew dust plumes all the way to North America, causing spectacular sunsets off San Francisco. But in the future, the result could be far less beautiful. Toxins picked up over Asia's urban centers hitch a ride on dust particles, creating a global highway for air pollution. is hoping that the Great Green Wall will begin working some magic before that happens - and prevent an international dustup.

10 years of environmental engineering

Italian army blows up 15,000 pounds of explosives to block lava flowing from Mount Etna to villages below.

Mexico City installs 20,000 air filters on streetlights in the smog-choked central district.

US approves an $8 billion project to rechannel a river as part of reengineering the 4 million-acre Florida Everglades.

Los Angeles builds a massive ground-based sprinkler system to control dust pollution in nearby Owens Valley.

New York City Transit dumps some 1,000 subway cars in the ocean off Delaware and South Carolina to serve as artificial reefs.

Construction begins on 's $3 billion plan to build hinged dams around Venice to keep the city from sinking.

First generators go online at 's Three Gorges Dam, a $24 billion project that will provide 18.2 million kilowatts of power by 2009.


© 2007 CondéNet Inc

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