IPCC
Intergovernmental Panel on Climate Change
In the 1970s and 1980s, a consensus developed among climate scientists that human activities, especially carbon dioxide emissions, should cause global warming. In 1988, the UN General Assembly directed the World Meteorological Organization and the United Nations Environment Programme to investigate the matter by forming the IPCC.
How does the IPCC work? "Hundreds of experts are involved on a voluntary basis in the preparation of IPCC reports. Coordinating Lead Authors and Lead Authors for IPCC reports are selected by the relevant Working Group/Task Force Bureau, under general guidance provided by the Session of the Working Group (or by the Panel in case of reports prepared by the Task Force on National Greenhouse Gas Inventories) from among experts listed by governments and participating organizations, and other experts known through their publications and works. None of them is paid by the IPCC."
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.