BEIJING -- A roughly two-mile thick cloud of soot and smog hanging over most of Asia is wrecking havoc on agriculture and health but masking the effects of global warming, a United Nations study found.
The atmospheric brown cloud made of different particles resulting mostly from burning coal is causing hundreds of thousands of deaths in Asia and billions of dollars in economic losses, the study said. But it helps reduce the impact of climate change by between 20% and 80%, said the report released Thursday by the Project Atmospheric Brown Cloud, established by the United Nations Environment Program.
The cloud's impact is worst over the developing countries in Asia, where some half of the world's population lives, the study said. The finding echoes previous research that found the soot from coal burning in countries like China, the world's leading user of coal, is helping mitigate global warming by shading the sun. Fossil fuels, when burned, emit both global-warming gases and pollutants that cause smog.
That finding illustrates the complexity of balancing economic growth against reducing pollution. Moving too quickly to reduce some types of pollution without reducing carbon dioxide and other greenhouse gasses could have disastrous consequences, the study said.
Eliminating the cloud would rapidly increase global temperatures two degrees Celsius, which coupled with the already measured rise of 0.75 degrees in the 20th century could push world climate past what scientists consider a dangerous threshold.
Outdoor pollutants could kill 340,000 people a year in China and India, while indoor pollution, from sources such as open wood fire stoves, is killing another 780,000 in the two countries, the UN said.
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