Sagan & Mullen (1972)
Also: Sagan & Mullen 1972
Earth and Mars: evolution of atmospheres and surface temperatures
Sagan, C., & Mullen, G. (1972). Earth and Mars: evolution of atmospheres and surface temperatures. Science, 177(4043), 52-56. Link to PDF
DOI: 10.1126/science.177.4043.52
References
All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.