SFGate | A new Chinese export has been spreading quietly across Asia and America: dust.
Violent sandstorms from China's expanding deserts have been battering Chinese cities, and their mustard-colored dust has begun reaching South Korea, Japan, and the West Coast of North America.
"People dusting off their cars in California or Calgary often don't realize the sand has come all the way from China," said Lester Brown, president of the Earth Policy Institute in Washington, D.C., who was in Beijing recently. "There is a dustbowl developing in China that represents the largest conversion of productive land to desert of any place in the world ... and it's affecting the world."
China has always suffered from aridity. About 25 percent of its landmass is composed of deserts made famous in tales about the Silk Road, which traversed many of them.
But the situation is getting worse.
Overgrazing, along with persistent drought, indiscriminate use of ground water, and rampant logging, are eroding the edges of China's deserts, allowing them to merge and spread. Recent satellite imagery shows that the Badain Jaran Desert in north-central China is pushing southward toward the nearby Tengger Desert to form a single, larger desert overlapping both northwestern Gansu province and neighboring Inner Mongolia.
Expanding deserts swallow almost a million acres of land every year, China's Environmental Protection Agency says. Soon, 40 percent of China could turn into scrubland, creating enormous social, economic and ecological challenges, including the problem of millions of "ecological refugees."