Huge Dust Plumes From China Cause Changes in Climate
One tainted export from China can't be avoided in North America -- air.
"There are times when it covers the entire Pacific Ocean basin like a ribbon bent back and forth," said atmospheric physicist V. Ramanathan at the Scripps Institution of Oceanography in La Jolla, Calif.
On some days, almost a third of the air over Los Angeles and San Francisco can be traced directly to Asia. With it comes up to three-quarters of the black carbon particulate pollution that reaches the West Coast, Dr. Ramanathan and his colleagues recently reported in the Journal of Geophysical Research.
The influence of these plumes on climate is complex because they can have
both a cooling and a warming effect, the scientists said. Scientists are convinced these plumes contain so many cooling sulfate particles that they may be masking half of the effect of global warming. The plumes may block more than 10% of the sunlight over the Pacific.
Asia is the world's largest source of aerosols, man-made and natural. Every spring and summer, storms whip up silt from the Gobi desert of Mongolia and the hardpan of the Taklamakan desert of western China, where, for centuries, dust has shaped a way of life. From the dunes of Dunhuang, where vendors hawk gauze face masks alongside braided leather camel whips, to the oasis of Kashgar at the feet of the Tian Shan Mountains 1,500 miles to the west, there is no escaping it. Only the dust escapes.
The team detected a new high-altitude plume every three or four days. Each one was up to 300 miles wide and six miles deep, a vaporous layer cake of pollutants. The higher the plumes, the longer they lasted, the faster they traveled the more pronounced their effect.
Until now, the pollution choking so many communities in Asia may have tempered the pace of global warming. As China and other countries eliminate their sulfate emissions, however, world temperatures may heat up even faster than predicted.