Biggest Emitters, by Country. Asia, China (#1), is the largest emitter, with the continent accounting for> 1/2 of global emissions. Yes, U.S. #2. Visualizing Changes in CO₂ Emissions Since 1900 For me, the surprising part was: CO₂ emissions from developing economies already account for more than TWO-THIRDS of global emissions, while emissions from adv economies are in...