The reduction of 63,000 tonnes is equivalent to the annual emissions of 17,500 cars, and follows a drive to reduce energy consumption and increase the use of biofuel throughout 2009.
Guy Mallinson, business director sales, said: "Even before this move, our business operations were robust and sustainable.
"Almost 95% of Iggesund Bruk's energy consumption is from biofuel and we have one more investment step left before our vision of a paperboard mill totally free of fossil CO2 will be a reality."
The company has a long-term environmental programme at the mill, with its energy supply based on heat from its own production process, plus electricity.
Iggesund's Bruk site produces the company's flagship brand Invercote.
