Clearing smog has led to 'global brightening'

New data show that after years of getting smoggier, our skies have become clearer since about 1990. And one effect has been to allow more solar radiation to reach the surface of the Earth.
The phenomenon known as “global dimming” has gone into reverse, according to research by Martin Wild at the Institute for Atmospheric and Climate Science in Zurich, Switzerland, and been replaced by “global brightening” (Science. vol 308, p 847). “There is no longer a dimming to counteract the greenhouse effect,” he told New Scientist.
Climate scientists say there have been two critical influences on global air temperatures in the past half-century. First, rising atmospheric concentrations of heat-trapping gases like carbon dioxide have warmed the Earth, by preventing more of the heat that reaches the Earth’s surface from escaping back into space.
But a parallel increase in smog particles has shaded the planet, partly offsetting the warming. Past studies have shown an increase in average aerosol particle levels in the atmosphere between 1960 and 1990 that were sufficient to reduce solar radiation reaching the Earth’s surface by about 5%.
The net effect of these two conflicting influences has been a warming of almost 0.5°C since 1960. But the rising levels of aerosols have led to concern that they might be masking greater underlying warming. And now the mask appears to be coming off.