China's journey to the dark ages
Biggest cities becoming murky as smog clouds block up to 25 per cent of sun, UN study finds
BEIJING — In the skies over China and South Asia, the sun itself is disappearing. The biggest cities are becoming darker as they fall beneath a vast brown cloud of soot, and even North America is vulnerable to the drifting toxic cloud.
That's the conclusion of a new United Nations study: that warns that the smog clouds have become so enormous they could kill 340,000 people annually in China and India.
The study says the toxic clouds - more than three kilometres thick - are contributing to a huge range of dangerous effects: extreme weather; damage to crops; melting of glaciers; the dimming of big cities; shifts in rainfall; massive economic losses; higher food prices; and a growing number of human deaths from respiratory and cardiovascular diseases.
Up to 25 per cent of the sunlight has disappeared in Chinese cities such as Beijing, Shanghai, Guangzhou, India's New Delhi and Karachi, Pakistan, the study concluded. In India, the dimming of cities has more than doubled since 1980, it said.
Although the clouds of haze are worst in China and South Asia, there are also "regional hot spots" in Southeast Asia, Southern Africa and the Amazon Basin of South America, the study found.
The smog clouds are also found in North America and Europe, but those are less dangerous because they tend to be removed or reduced by winter precipitation. The clouds from Asia, however, have drifted as far east as California.
The clouds, known as "atmospheric brown clouds," are filled with ozone, black carbon, and soot particles. They are caused by a "soot stream" of fossil-fuel and biomass burning, deforestation and other man-made factors. Coal-fired power plants and rising auto traffic are among the chief causes.
A team of scientists, commissioned by the UN Environment Programme, has been studying the toxic brown clouds since 2002. Their first reports met with considerable cynicism and criticism, but their latest report is much more detailed, prompting the scientists to issue a stronger warning of the importance of the issue.
Achim Steiner, the UNEP executive director, said he expects the phenomenon of toxic brown clouds to be "firmly on the international community's radar" as a result of the latest study, which was released yesterday. The clouds need "urgent and detailed research," he said.
In China alone, the clouds have cost an estimated $82-billion in losses to the national economy, he said.
One of the most disturbing problems is the impact of the smog clouds on global warming. This happens in two ways. By absorbing sunlight and heating the air, the clouds are aggravating the effect of greenhouse gases. But at the same time, the clouds can be "masking" the global-warming trend, since they contain sulphates and other particles that can reflect sunlight and cool the Earth's surface. So any action to eliminate the brown clouds would trigger a dramatic rise in global warming, the study warns.
The clouds could be dampening the rise of global temperatures by 20 to 80 per cent, the study said. "Simply tackling the pollution linked with brown-cloud formations, without simultaneously delivering big cuts in greenhouse gases, could have a potentially disastrous effect," the UNEP said in a statement yesterday.
It also warned that the clouds are reducing rainfall in India and South Asia, which could "further aggravate the recent dramatic escalation of food prices and the consequent challenge for survival among the world's most vulnerable populations."
In parts of India, for example, the brown clouds - combined with global warming - have slashed the rice harvest by 6.2 million tonnes annually, which is enough to feed 72 million people, the study found.
Another dramatic result is the melting of glaciers, partly due to the toxic clouds. The latest study found "substantial soot concentrations" in the Himalayan mountains, even up to an altitude of five kilometres. And this soot, along with greenhouse gases, is a major cause of the melting and shrinking of glaciers.
"If the current rate of retreat continues unabated, these glaciers and snow packs are expected to shrink by as much as 75 per cent before the year 2050, posing grave danger to the region's water security," the study concluded.