The IPCC is open to all member countries of the United Nations (UN) and the World Meteorological Organization (WMO). There are at present 194 countries.

The Panel and its Plenary Sessions

The Panel, comprised of government delegations of all member countries, meets approximately once a year at the plenary level. These Sessions are attended by hundreds of officials and experts from relevant ministries, agencies and research institutions from member countries and from observer organizations. Major decisions such as the election of the IPCC Chair, IPCC Bureau and the Task Force Bureau, the structure and mandate of IPCC Working Groups and Task Forces, as well as on procedural matters, work-plan and budget are taken by the Panel in plenary Session. The Panel decides also on scope and outline of IPCC reports and accepts the reports.

How the work of the IPCC is organized

The IPCC is a huge and yet very tiny organization. Thousands of scientists all over the world contribute to the work of the IPCC on a voluntary basis as authors, contributors and reviewers. None of them is paid by the IPCC. Their work is supported by a central IPCC Secretariat, whose role is to plan, coordinate and oversee all IPCC activities and by the Technical Support Units of the Working Groups and Task Force. The Secretariat and the TSUs employ 5-10 people each.

The IPCC is currently organized in 3 Working Groups. Working Group I deals with "The Physical Science Basis of Climate Change", Working Group II with "Climate Change Impacts, Adaptation and Vulnerability" and Working Group III with "Mitigation of Climate Change". They are assisted by a Technical Support Unit, which is hosted and financially supported by the government of the country who offered to do so.

The IPCC has also a Task Force on National Greenhouse Gas Inventories. The main objective of the Task Force is to develop and refine a methodology for the calculation and reporting of national GHG emissions and removals. In addition to the Working Groups and Task Force, further Task Groups and Steering Groups may be established for a limited or longer duration to consider a specific topic or question.