IPCC reports cover the "scientific, technical and socio-economic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts and options for adaptation and mitigation." The IPCC does not carry out original research, nor does it monitor climate or related phenomena itself. Rather, it assesses published literature including peer-reviewed and non-peer-reviewed sources. However, the IPCC can be said to stimulate research in climate science. Chapters of IPCC reports often close with sections on limitations and knowledge or research gaps, and the announcement of an IPCC special report can catalyse research activity in that area.
Thousands of scientists and other experts contribute on a voluntary basis to writing and reviewing reports, which are then reviewed by governments. IPCC reports contain a "Summary for Policymakers", which is subject to line-by-line approval by delegates from all participating governments. Typically, this involves the governments of more than 120 countries.
The IPCC provides an internationally accepted authority on climate change, producing reports which have the agreement of leading climate scientists and the consensus of participating governments. The 2007 Nobel Peace Prize was shared, in equal parts, between the IPCC and Al Gore.
Following the election of a new Bureau in 2015, the IPCC embarked on its sixth assessment cycle. Besides the Sixth Assessment Report, to be completed in 2022, the IPCC released the Special Report on Global Warming of 1.5ºC in October 2018, will release an update to its 2006 Guidelines for National Greenhouse Gas Inventories—the 2019 Refinement—in May 2019, and will deliver two further special reports in 2019: the Special Report on the Ocean and Cryosphere in a Changing Climate, and Climate Change and Land. This makes the sixth assessment cycle the most ambitious in the IPCC's 30-year history. The IPCC also decided to prepare a special report on cities and climate change in the seventh assessment cycle, and held a conference in March 2018 to stimulate research in this area.
The IPCC developed from an international scientific body, the Advisory Group on Greenhouse Gases set up in 1985 by the International Council of Scientific Unions, the United Nations Environment Programme (UNEP), and the World Meteorological Organization (WMO) to provide recommendations based on current research. This small group of scientists lacked the resources to cover the increasingly complex interdisciplinary nature of climate science. The United States Environmental Protection Agency and State Department wanted an international convention to agree restrictions on greenhouse gases, and the conservativeReagan Administration was concerned about unrestrained influence from independent scientists or from United Nations bodies including UNEP and the WMO. The U.S. government was the main force in forming the IPCC as an autonomous intergovernmental body in which scientists took part both as experts on the science and as official representatives of their governments, to produce reports which had the firm backing of all the leading scientists worldwide researching the topic, and which then had to gain consensus agreement from every one of the participating governments. In this way, it was formed as a hybrid between a scientific body and an intergovernmental political organisation. The Intergovernmental Panel on Climate Change assesses peer-reviewed scientific literature and other relevant publications to provide information on the state of knowledge about climate change. It does not conduct its own original research. It produces comprehensive assessments, reports on special topics, and methodologies. The assessments build on previous reports, highlighting the latest knowledge. For example the wording of the reports from the first to the fifth assessment reflects the growing evidence for a changing climate caused by human activity.
The IPCC has adopted and published "Principles Governing IPCC Work", which states that the IPCC will assess:
This document also states that IPCC will do this work by assessing "on a comprehensive, objective, open and transparent basis the scientific, technical and socio-economic information relevant to understanding the scientific basis" of these topics. The Principles also state that "IPCC reports should be neutral with respect to policy, although they may need to deal objectively with scientific, technical and socio-economic factors relevant to the application of particular policies."