Generally speaking sandstorms are not getting worse in Beijing
though the yellow dust cloud that swept around the Chinese capital
on Wednesday is one of the worst in recent years, said
meteorological experts.
Sandstorms hitting north China have not increased in intensity or
frequency since the 1950s, said Zhang Guocai, director of the
National Meteorological Center. "Serious ones like today's have
been quite rare in recent years," he added.
The unpleasant weather phenomenon began two weeks later this year
than in previous years. The city was already affected by sandstorms
during the New Year's Day holiday in 2001.
Not keeping with their regular timetable, the sandstorms
fortunately did not hit Beijing during the two-week annual annual
sessions of China's top legislative and political advisory bodies,
which lasted until mid-March.
Windy and dusty weather is quite common in Beijing, and some people
may have confused flying dust with sandstorms, said Liu Shu, a
senior expert for sand control.
"The minute dust particles that sometimes float around do not
necessarily constitute a sandstorm," he explained, "This dust
mainly comes from infertile farm land and exposed pastures."
Sandstorms that do sometimes hit Beijing are usually moderate not
severe, Liu said.
Dusty weather comes from the interaction of strong wind and
existing sand blown off deserts and desertified grassland, which,
in turn, is the result of excessive cultivation and grazing, said
Zhang Guocai.
Though the reducing acreage of pasture land is the main reason for
floating dust and sandstorms in north China, the weather is another
deciding factor for their occurrence, frequency and intensity,
Zhang said.
According to Zhang, stable weather conditions and the absence of
strong winds explain the late arrival of dust storms this year, but
other experts disagree.
Ma
Wenyuan, an expert in counter-desertification studies, attributes
the late coming sandstorms to the warm winter.
"Sandstorms used to arrive in north China in February, when cold
winds met with an early spring thaw," he explained.
The past warm winter meant an early thaw, he said, "And there were
no cold currents to produce dusty weather this February."
The strong wind that blew on March 15 and 16 brought the year's
first dusty weather in north China, but the chill factor was not
strong enough to cause a serious sandstorm, he added.
However, experts do not exclude the possibility that severe
sandstorms will come again in April. "Actually, sandstorms cannot
possibly be avoided as a 200,000-square-kilometer desert extends
from Hebei Province to Inner Mongolia," said Ma.
Forestation is by far the most effective means to prevent or reduce
their occurrence, say experts. China has a plan to curb
desertification in ten years by reining in sands, planting trees,
reclaiming more farming land and preserving pastures in north
China.
Beijing has also decided to speed up construction of more "green
screens" to fend off sands coming from the northwest. This year,
the Chinese capital plans to green 24,300 hectares of its land, say
sources from the municipal landscaping committee.
"By 2007, 50 percent of Beijing will be covered in plants and the
per capita greenland will reach 50 square meters," says a Beijing
landscaping official.
(Xinhua News
Agency March 22, 2002)