Heat pump the brand name Freon, a trademark of DuPont. Its manufacture is now banned or severely restricted by the Montreal Protocol of August 1987 because of the damage that CFCs cause to the ozone layer if released into the atmosphere. One widely adopted replacement refrigerant is the hydrofluorocarbon (HFC) known as R-134a (1,1,1,2-tetrafluoroethane). Heat pumps using R-134a replaced R-12 (dichlorodifluoromethane) and have similar thermodynamic properties but with insignificant ozone depletion potential and a somewhat lower global warming potential. Other substances such as liquid R-717 ammonia are widely used in large-scale systems, or occasionally the less corrosive but more flammable propane or
Canada and the Kyoto Protocol of compliance has been estimated 20 times lower. States for which the emissions are not covered by the Kyoto Protocol (the US and China) have the largest emissions, being responsible for 41% of the Kyoto Protocol. China's emissions increased by over 200% from 1990 to 2009. Canadian Council of Chief Executives VP John Dillon argued (2011-11-22) that a further extension of Kyoto would not be effective as many countries, not just Canada, were not on track to meet their 1997 Kyoto commitments to reduce emissions. He called for a comprehensive, long-term global agreement that includes major emitters like the US,