new culprit identified!

In the charge against global warming, carbon dioxide has long held sway as public enemy number one. But now, less-recognized molecules are entering the fray as significant agents of global warming.

Aerosols emitted from smokestacks, exhaust pipes and domestic cooking fires consist of substances such as sulphates and nitrates that scatter light and have a local cooling effect; they also contain black carbon — or soot — a byproduct of incomplete combustion, which absorbs light.

In a study published recently in Nature2, Veerabhadran Ramanathan, an atmospheric scientist at the Scripps Institution of Oceanography in La Jolla, California, and colleagues, report that aerosols locked up in brown clouds over Asia are significant contributors to regional warming.

“Brown clouds from the United States cover the Atlantic, the European brown cloud goes over central Asia, and China’s brown cloud crosses the Pacific over to us,” says Ramanathan. “We are each a back yard to someone else, and we’re polluting every other person’s back yard.”

Nature Reports, 9 Jul 2007