Asian Brown Cloud' poses global threat
August 12, 2002 Posted: 11:32 AM EDT (1532 GMT)
The lives of millions of people are at risk, both from the toxic
haze and the weather change it brings, the study shows
By CNN's Marianne Bray
and wire reports
HONG KONG, China -- A dense blanket of pollution, dubbed the
"Asian Brown Cloud," is hovering over South Asia, with
scientists warning it could kill millions of people in the
region, and pose a global threat. In the biggest-ever study of
the phenomenon, 200 scientists warned that the cloud, estimated
to be two miles (three kilometers) thick, is responsible for
hundreds of thousands of deaths a year from respiratory disease.
By slashing the sunlight that reaches the ground by 10 to 15
percent, the choking smog has also altered the region's climate,
cooling the ground while heating the atmosphere, scientists said
on Monday. EXTRA INFORMATION
Asia's 'brown cloud': The facts
The potent haze lying over the entire Indian subcontinent -- from
Sri Lanka to Afghanistan -- has led to some erratic weather,
sparking flooding in Bangladesh, Nepal and northeastern India,
but drought in Pakistan and northwestern India. "There are
also global implications, not least because a pollution parcel
like this, which stretches three kilometers high, can travel half
way round the globe in a week, " U.N. Environment Program
chief Klaus Toepfer told a news conference in London on Sunday.
The U.N.'s preliminary report comes three weeks before the Earth
Summit in Johannesburg, which opens on August 26, where all eyes
will be on how not to overburden the planet. Global threat
While haze hovers over other parts of the world, including
America and Europe, what surprised scientists was just how far
the cloud extended, and how much black carbon was in it,
according to A P Mitra from India's National Physical Laboratory.
Asia's brown haze is altering the weather, creating acid rain
A cocktail of aerosols, ash, soot and other particles, the haze's
reach extends far beyond the study zone of the Indian
subcontinent, and towards East and Southeast Asia. While many
scientists once thought that only lighter greenhouse gases, such
as carbon dioxide, could travel across the Earth, they now say
that aerosol clouds can too. "Biomass burning" from
forest fires, vegetation clearing and fossil fuel was just as
much to blame for the shrouding haze as dirty industries from
Asia's great cities, the study found. A large part of the aerosol
cloud comes from inefficient cookers, where fuels such as cow
dung and kerosene are used to cook food in many parts of Asia,
says Mitra. Acid rain
Using data from ships, planes and satellites to study Asia's haze
during the northern winter months of 1995 to 2000, scientists
were able to track its journey to pristine parts of the world,
such as the Maldives, to see how it affected climate. They
discovered not only that the smog cut sunlight, heating the
atmosphere, but also that it created acid rain, a serious threat
to crops and trees, as well as contaminating oceans and hurting
agriculture. "It was much larger than we thought," said
Mitra. The report suggested the pollution could be cutting
India's winter rice harvest by as much as 10 percent. The report
calculated that the cloud -- 80 percent of which was man-made --
could cut rainfall over northwest Pakistan, Afghanistan, western
China and western central Asia by up to 40 percent. While
scientists say they still need more scientific data, they suggest
the regional and global impact of the haze will intensify over
the next 30 years. Nobel laureate Paul Crutzen -- one of the
first scientists to identify the causes of the hole in the ozone
layer and also involved in the U.N. report -- said up to two
million people in India alone were dying each year from
atmospheric pollution. In the next phase of the project,
scientists will collect data from the entire Asian region, over
more seasons with more observation sites and refine their
techniques. But because the lifetime of pollutants is short and
they can be rained out, scientists are hopeful that if Asians use
more efficient ways of burning fuel, such as better stoves, and
cleaner sources of energy, time has not run out.