April 18, 2010 - Anyone who grew up in Los Angeles during the 1960's and 70's remembers the days of smog alerts, sunny days when yellow air made it impossible to see more than a mile and breathing deeply was painful. One of the most remarkable things to happen to the city was legislation including US Clean Air Act. The result of that legislation is that even though the city's population has tripled the air is the cleanest it's been in half a century. Across the US one major air pollutant, sulfate aerosols, have been cut by 30% to 50% since the 1980s.
But even as industrialized and developing nations alike steadily reduce air pollution -- caused primarily by burning coal -- climate scientists are beginning to understand just how much these tiny particles have helped keep the planet cool. A silent benefit of sulfates, in fact, is that they've been helpfully blocking sunlight from striking the Earth for many decades, by brightening clouds and expanding their coverage. Emerging science suggests that their underappreciated impact has been incredible.
Here's the full story from Eli Kintisch LA Times
