SULPHUR POLLUTaNTS from coal-fired power stations in China have tended to cool the global climate over the past decade in contrast to the warming effect resulting from rising concentrations of carbon dioxide and other greenhouse gases, scientists have found.  a study has shown that the levelling of global average surface temperatures between 1998 and 2009 can be explained by the cooling effect resulting from the sulphur-containing gases emitted from mainly Chinese power stations over the same time period.  although carbon dioxide emissions have risen during the past decade, surface temperatures have not followed the same rapid increase seen in the previous three decades, which has led some climate sceptics to suggest that global warming this century has "stopped".  However, a stu