LA Times: Clean air produces global warming

You're likely to hear a chorus of dire warnings as we approach Earth Day, but there's a serious shortage few pundits are talking about: air pollution. That's right, the world is running short on air pollution, and if we continue to cut back on smoke pouring forth from industrial smokestacks, the increase in global warming could be profound.

Cleaner air, one of the signature achievements of the U.S. environmental movement, is certainly worth celebrating. Scientists estimate that the U.S. Clean Air Act has cut a major air pollutant called sulfate aerosols, for example, by 30% to 50% since the 1980s, helping greatly reduce cases of asthma and other respiratory problems.

But even as industrialized and developing nations alike steadily reduce aerosol 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.