BANGKOK, Thailand — China’s skies have darkened over the past 50 years, possibly due to haze resulting from a nine-fold increase in fossil fuel emissions, according to researchers from the U.S. Department of Energy. The researchers, writing in this month’s edition of Geophysical Research Letters, found that the amount of solar radiation measured at more than 500 stations in China fell from 1954 to 2001 despite a decrease in cloud cover. “Normally, more frequent cloud-free days should be sunnier and brighter but this doesn’t happen in our study,” said Yun Qian of the energy department’s Pacific Northwest National Laboratory in Washington state. “The pollution (that) resulted from human activity may have created a haze which absorbs and deflects the sun’s rays,” Qian, the study’s lead author, said in an e-mail interview Friday. Air pollution is widespread in China. Antiquated factories billow smoke, many residents still use coal to heat their centuries-old houses, and a sharp increase in car ownership has bathed the motorways in exhaust fumes. Using data from more than 500 weather stations in China, researchers found the amount of sunlight hitting the ground has fallen by 3.7 watts per square yard in each […]