The Intergovernmental Panel on Climate Change (IPCC) is the scientific body compiling the current state of climate change and providing orientation to policymakers for their decisions. The United Nations Environment Programme (UN Environment) and the World Meteorological Organization (WMO) established the IPCC in 1988. Since then, the IPCC has published five Assessment Reports and several special reports. These lay out the latest findings in climate research, point out the risks and consequences of climate change and highlight options for mitigation and adaptation strategies. The IPCC itself does not conduct any scientific research work. Many internationally renowned scientists work with transparency and diligence to compile the panel's reports on the basis of scientific publications from various journals. For this purpose, they use peer-reviewed journals as much as possible. Publications that have not been approved by independent reviewers such as authorities or international organisations have to be reviewed very carefully. Government representatives of the 195 parties to UN Environment or WMO are given the opportunity to comment on the drafts of IPCC reports before publication and to negotiate the phrasing of summaries for policymakers.
After the IPCC concluded its Fifth Assessment Report in 2013 and 2014 and the new IPCC bureau was elected in October 2015, work began on the Sixth Assessment Report, to be published in 2021 and 2022.
In addition to this, the IPCC is working on three special reports that are to be adopted by 2019. The special reports focus on land use, oceans/cryosphere and 1.5 degrees Celsius global warming. The report on 1.5 degrees Celsius global warming is intended to support the Conference of the Parties to the UNFCCC in 2018 and the discussions on nationally determined contributions.
Organisation of IPCC
There are three working groups in the IPCC, each of which produces one volume of the assessment reports. Working group I deals with the physical science basis of climate change. Working group II assesses the climate change vulnerability of socio-economic and natural systems and describes options for human adaptation to global warming. Working group III focusses on strategies for mitigation of climate change. In addition, IPCC task forces are established to tackle selected topics, usually within a specific time frame. For example, one task force is devoted to methods for calculating greenhouse gas emissions for national inventories. The working groups and the task forces work on the basis of mandates adopted by the plenary session.
Government representatives from the parties convene regularly for plenary sessions. At these sessions, the plenary determines topics for future assessment reports, adopts summaries of the respective assessment reports for political decision makers and consults on rules of procedure, for example, for drawing up reports. The plenary session also elects the IPCC bureau.
In October 2015, Hoesung Lee of South Korea was elected as the new chair of the IPCC. The German biologist and climate researcher Hans-Otto Pörtner of the Alfred Wegener Institute was elected as co-chair of working group II. The bureau's term of office covers the duration of the assessment cycle up to the presentation of the Sixth IPCC Assessment Report in 2022.
The IPCC, its executive committee and bureau are supported in their work by the Secretariat in Geneva and the national IPCC focal points - in Germany that is the Federal Environment Ministry. The German IPCC Coordination Office, run jointly by the Federal Environment Ministry and the Federal Ministry of Education and Research, supports the IPCC focal point in its work.
To date, five assessment reports have been completed. These reports are published by the three working groups at intervals of six to seven years. The synthesis report contains the reports drawn up by the working groups, summarises the results and puts them in an overarching context.
Fifth Assessment Report
In 2013/2014, the IPCC adopted its Fifth Assessment Report (AR5). The report substantiates human influence on the climate system and therefore confirms the reality of an anthropogenic climate change. It also describes the associated risks and consequences as well as strategies for adaptation and mitigation.
The first volume of this report, on the physical science basis of climate change, was published in Stockholm in September 2013. Volumes II and III were adopted in Yokohama in March 2014 and in Berlin in April 2014 respectively. The session in Berlin was presided over by German economist Ottmar Edenhofer of the Potsdam Institute for Climate Impact Research (PIK), co-chair of IPCC Working Group III during the assessment cycle for the Fifth Assessment Report. The synthesis report was published in Copenhagen in October 2014.
The preparation of reports must follow certain procedures. At the outset, the plenary session makes the decision to prepare a report and determines the scope for the working groups. Authors are then selected for the three working groups. The governments of the 195 member countries and around 100 accredited observer organisations may suggest suitable authors. The working group bureaus select the authors from the list of nominees.
These teams are composed of many experts – the co-chairs of the working groups, coordinating lead authors and lead authors, contributing authors and reviewers for the respective chapters. Some 830 authors were involved in preparing the Fifth Assessment Report, including 40 experts from German universities, research institutes and the private sector. The composition of the groups of authors ensures that they represent a variety of points of view, in addition to pertinent expertise.
Gender and region are also taken into account to ensure that the groups of authors are well-balanced. To compile a report, authors mainly draw from articles published in peer-reviewed journals. Authors have to agree on a way to present and scientifically assess the facts. Disparate views, knowledge gaps and uncertainties are explicitly mentioned in the report. The first drafts prepared by the working groups are reviewed several times by experts and government representatives and revised in the process.
The summaries for policymakers are also approved by governments line by line. In doing so, the governments acknowledge the scientific assertions in the assessment reports. The reports can then be published and presented.