While a few regions are still experiencing global dimming due to aerosols and dust, according to two studies conducted in 2005, many areas are now witnessing some increased brightness as a result of pollution abatement. However, this brightness brings reason to worry: air pollution may have masked the effects of climate change, and additional solar brightening may hasten temperature rising.

• Wild, Martin et al. "From Dimming to Brightening: Decadal Changes in Solar Radiation at Earth’s Surface." Science 308(5723): 847-850. 6 May 2005 at www.sciencemag.org

• Pinker, R. T. et al. "Do Satellites Detect Trends in Surface Solar Radiation?" Science 308(5723): 850-854. 6 May 2005 at www.sciencemag.org

The degree to which global dimming has shielded climate change effects is still unclear, and scientists are in the process of researching the linkage. Preliminary research conducted by Martin Wild suggests that air pollution prior to 1990 may have protected us from 50% or more of warming.

Implications: Air pollution, which blocks some amount of solar radiation, may have shielded us from climate change impacts. Because major urban areas have been successful in abating pollution (with consequent improvement in air quality), particles that block incoming solar radiation have been reduced, and, as a result, incoming solar radiation reaching the earth is stronger. Increases in incoming radiation increase the Earth's warming -- and thus, climate change impacts may be augmented in the future as a result.