Intergovernmental Panel on Climate Change     
http://www.ipcc.ch/

National Oceanic and Atmospheric Administration    
http://www.noaa.gov/climate.html

United Nations Framework Convention on Climate Change   
http://unfccc.int/

Emissions Database for Global Atmospheric Research
http://www.rivm.nl/en/milieu/

International Energy Agency, Greenhouse Gas Programme
http://www.ieagreen.org.uk

Carbon Dioxide Information Analysis Center
http://cdiac.esd.ornl.gov