Topic: Decrease in airborne pollutants and aerosols could be warming the globe...

[Orstio]

http://www.nasa.gov/centers/goddard/news/topstory/2007/aerosol_dimming.html

A new NASA study has found that an important counter-balance to the warming of our planet by greenhouse gases – sunlight blocked by dust, pollution and other aerosol particles – appears to have lost ground.

The thinning of Earth’s “sunscreen” of aerosols since the early 1990s could have given an extra push to the rise in global surface temperatures. The finding, published in the March 16 issue of Science, may lead to an improved understanding of recent climate change. In a related study published last week, scientists found that the opposing forces of global warming and the cooling from aerosol-induced "global dimming" can occur at the same time.

[Astronuc]

I have heard such a concern regarding China.  Apparently the sulfur dioxide and soot from Chinese fossil-fueled power plants contributes some cooling effect, which balances their contribution of greenhouse gases.  So, if China cleans up the air pollution, that might contribute to GW.  On the other hand, the air is so polluted in many Chinese cities that respiratory illnesses are significant.

[remcook]

this might actually be part of the reason that in the first half of the last century, the effects of global warming were not very apparent. This issue is a bit ironic, but the solution is just to emit less CO2.