BEIJING -- A thick brown cloud of soot, particles and chemicals stretching from the Persian Gulf to Asia threatens health and food supplies in the world, the U.N. reported Thursday, citing what it called the newest threat from global warming.The regional haze, known as atmospheric brown clouds, contributes to the melting of Himalayan glaciers, reduces sunlight, and helps create extreme weather conditions that impact agricultural production, according to the report commissioned by the U.N. Environment Program.
These so-called "brown clouds," caused by the burning of fossil fuels, wood and plants, play a significant role in exacerbating the effects of greenhouse gases in warming up the earth's atmosphere, the report said.
"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 during a news conference on the findings.
"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.
The phenomenon complicates the climate change scenario globally because the brown clouds also help cool the earth's surface and "masks" the impact of global warming by an average of 40 percent, the study said.
Though it has been studied closely in Asia, 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 enormous cloud masses can move across continents within three to four days, said lead scientist, Veerabhadran Ramanathan, with the Scripps Institution of Oceanography at the University of California in San Diego.
"The main message is that it's a global problem. Everyone is in someone else's backyard," said Ramanathan.
The report also noted that health problems associated with particulate pollution, which include cardiovascular and respiratory diseases, are linked to nearly 350,000 premature deaths in China and India every year, said Henning Rohde, a University of Stockholm scientist who worked on the study.
