Reuters: Global emissions of the commonest man-made greenhouse gas carbon dioxide will fall by the sharpest rate in 40 years in 2009 following tumbling factory output, the International Energy Agency said on Monday. The world must use the drop of about 2.6 percent to drive a global fight against climate change, rather than allow emissions to rise again as after previous recessions, Fatih Birol, IEA chief economist, told Reuters in an interview. “The biggest fall (in about 40 years) was …