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Brown Smog Clouds Mask Impacts of Global Warming

November 13, 2008

Thick smog clouds that loom over Asia threaten the livelihood of crops and contain particles that actually reflect the sun’s rays away from the earth, the United Nations reported on Thursday.

“One of the impacts of this atmospheric brown cloud has been to mask the true nature of global warming on our planet,” United Nations Environment Program (UNEP) head Achim Steiner said at the launch in Beijing of a new report on the phenomenon.

Caused by the burning of fossil fuels, wood and plants, these brown clouds of soot, particles and chemicals stretch from the Persian Gulf all the way to Asia. They have been linked to the melting of Himalayan glaciers and extreme weather conditions that impact agricultural production, according to the report commissioned by UNEP.

“Imagine for a moment a three-kilometer-thick (1.8-mile-thick) band of soot, particles, a cocktail of chemicals that stretches from the Arabic Peninsula to Asia,” said Achim Steiner, U.N. undersecretary general and executive director of the UN program.

“All of this points to an even greater and urgent need to look at emissions across the planet because this is where the stories are linked in terms of greenhouse emissions and particle emissions and the impact that they’re having on our global climate,” he said.

Experts fear that the actual impact of global warming may not be fully understood because of the cooling effect of brown clouds. The clouds also actually speed up warming in some of the most vulnerable areas and exacerbating the most devastating impacts of higher temperatures.

The U.N. report found that brown clouds may be masking’ the warming impacts of climate change by between 20 and up to 80 percent.

Scientists are still studying the impact on crops, but possible problems include falling harvests because of less energy for photosynthesis and higher ozone concentrations.

“The emergence of the atmospheric brown cloud problem is expected to further aggravate the recent dramatic escalation of food prices and the consequent challenge for survival among the world’s most vulnerable populations,” the report said.

The latest findings, conducted by an international collaboration of scientists, reveal that the brown cloud phenomenon is not unique to Asia, with pollution hotspots seen in North America, Europe, South Africa and South America.

“The main message is that it’s a global problem. Everyone is in someone else’s backyard,” said lead scientist, Veerabhadran Ramanathan, with the Scripps Institution of Oceanography at the University of California in San Diego.

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