you redistribute solar energy within the atmospheric column, it has a
considerable impact on the properties of clouds,” Prospero says. “It’s a
complex system with a lot of feedbacks that are not clear yet.”
Prospero adds that National Science Foundation grant reviewers
had originally doubted the researchers would find anything measura-
ble. “But the size of what we saw didn’t surprise me because I’ve been
running cruises in that area for many years,” he says. “And anyone
who’s ever been to India knows there’s a lot of pollution there. It’s
scary, and it’s the way it will go in all of Asia.”
POLLUTIONTRAVELS
And the soot may not remain in Asia, because pollution does not
always stay put. Scientists say that the pollution cloud could travel
around the world in less than a week, carried in the upper atmosphere.
Atmospheric chemist David P. Parrish of the National Oceanic and
Atmospheric Administration Aeronomy Lab in Boulder, Colorado, says
recent research reveals a disturbing fact: According to National Science
Foundation–supported work in 2001, Asian soot particles are “piggy-
backing” on dust clouds blown from Asia to the west coast of the
United States. “When particles run into each other they tend to stick
together,” he says. “It’s all being transported on the same air mass.”
The full extent of the problem is not yet apparent, Parrish says.
“We’re beginning to feel our way around the elephant,” he said. “Only
a relatively few episodes have been studied in detail.” The net effect,
Parrish adds, is to increase both global warming and coastal pollution.
“The dust tends to scatter solar radiation back into space,” he said,
“while the soot absorbs it, heating the atmosphere.”
Parrish notes that a study of springtime ozone levels in California
showed that they had increased by a third between 1985 and 2002.
“We can point to Asia as the likely cause, but we have no clear evi-
dence,” he said. “The increase was larger than we had expected, and it
reduces the latitude we have to mess up our own air.”
There is no question that dust can move across considerable dis-
tances. Dust storms are as old as time and completely natural, but our
ability to track their peripatetic journeys around the world is relatively
Asia 89