Most of the world's greenhouse gas (GHG) emissions come from a relatively small number of countries. China, the United States, and the 27 nations that make up the European Union (EU-27) are the three largest emitters on an absolute basis.
Sources: International Energy Agency, World Energy Outlook (2012)
International Energy Agency, CO2 Highlights (2011)
U.S. Environmental Protection Agency, International Non CO2 Projections (2012)